Difference between revisions of "Mercury - intermodulation (IMD) tests"

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−	The HPSDR is an open source (GNU type) hardware and software project intended as a "next generation" Software Defined Radio (SDR) for use by Radio Amateurs ("hams") and Short Wave Listeners (SWLs).  It is being designed and developed by a group of SDR enthusiasts with representation from interested experimenters worldwide.  The discussion list membership currently stands at over 900 and includes such SDR enthusiasts as Ray Anderson WB6TPU, Steve Bible N7HPR, Rick Hambly W2GPS, Phil Harman VK6APH, Lyle Johnson KK7P, Ulrich Rohde N1UL, and Bill Tracey KD5TFD to name a few.	+	<!-- Original title: '''HPSDR: Intermodulation Measurements with MERCURY'''May/June 2009 / HB9AJG
		+	Phil Harman's page title: Intermodulation Measurements with MERCURY -->
		+	The use by Amateurs of receivers that use Digital Down Conversion (DDC), where the antenna is effectively connected directly to an Analogue to Digital Converter (ADC), is relatively new.
−	The rationale behind the project is to break the overall design up into a number of modules.  Each module is designed by an individual or group and connects to other modules using a pre-defined and common bus -- rather like plugging boards into a PC motherboard.	+	DDC based receivers perform differently to conventional analogue receiver particularly when intermodulation (IMD) testing is performed.  Unlike an analogue receiver the IMD varies with the level of input signals. This renders the value of conventional 3rd order intercept (IP3) meaningless.
−	This modular approach enables users to incorporate just the modules that interest them as well as designing their own variants if desired. The approach also enables new ideas and circuits to be tested by replacing an existing module. Since the majority of modules will be retained, such experimentation can be done with minimum disruption to an existing working system.	+	The reason for the variation of IP3 with signal level is that for small input signals only a small number of the available ADC bits are actually used. Also since these are near the origin of the ADC transfer curve there are often imperfections that degrade the IP3 performance.
−	The modules vary in complexity from simple bandpass filters and input/output interfaces, to full blown DSP functions.  Such variety enables experimenters with varying degrees of experience to contribute.  If you wish to contribute your skills to this project, the best way is to advise your availability on the discussion list and communicate with project leaders -- or if you have a proposal for a new module, fly it on the discussion list and if feasible, become a project leader!	+	We can reduce the effect of the limited number of bits and ADC non-linearity by deliberately adding additional signal(s) into the input of the ADC such that our low level signals are added to the (larger) additional signal(s). In effect the larger signal sweeps our small signal over a wider portion of the ADC transfer curve. This means that our combined signal spends less time over any non-linear portions and also uses more ADC bits.
−	The modules have each been named for easier identification when talking or writing about them.  On this wiki, each module has its own page, as noted by the links below.  Some of the modules are being designed so that they can be either used in conjunction with others or stand-alone.  Each module board size (except the backplane) will be 100 mm by 120 to 220 mm and use either a 64 pin or 96 pin DIN41612 type connector.	+	You can perhaps think of the additional signal giving the small signal a ‘piggy back ride’ across the ADC transfer curve.
		+	As long as the instantaneous sum of the additional signal(s) and our wanted signal does not overload our ADC then the overall effect is beneficial.
−	== HPSDR History and Philosophy ==	+	So here is a significant difference between our existing analogue receivers and a DDC based receiver. In the former case we go to a lot of trouble to keep large out of band signals out of the input of the receiver. In the latter case, up to a certain level, they actually are an advantage!
−	The High Performance SDR project was started in October, 2005	+	The additional signal(s) can come from a number of sources. The LT2208 ADC that is used in [[MERCURY|Mercury]] has the facility to inject pseudo random noise into its input. This noise can then be subtracted at the output. This technique is known as ‘dithering’.
−	by Phil Covington (N8VB) as the Open_High_Performance_SDR @ Yahoo group. In	+
−	November, 2005 another small group, based on the Xylo board	+
−	product (an FPGA experimenter's board) with SDR applications in	+
−	mind, evolved and the Xylo-SDR discussion list was formed. On	+
−	March 1, 2006 the two groups merged to form HPSDR and the two	+
−	discussion lists were replaced with the present HPSDR list.	+
−	Initially a small group of developers, HPSDR has grown to over	+	By subtracting the noise at the output of the ADC we only degrade the overall signal to noise ratio of the ADC by a few dB. Alternatively, we could inject an out-of-band signal into the antenna socket and use this as a source of dithering. Or perhaps there are enough strong signals already present at the input of the ADC to perform the dithering function so there is no need to either inject random noise or a specific out of band signal.
−	800 members, including hardware, software and firmware	+
−	developers; system architects; analog and digital designers; RF	+
−	engineers; planners, executers and users; testers, documenters	+
−	and technicians; bank presidents and sanitation engineers. While	+
−	the last two are dubious, the point is that HPSDR is a diverse	+
−	group. Everyone has something to contribute and all are	+
−	encouraged to participate.	+
−	The rationale behind HPSDR is to break the overall design up into	+	So is the effect of poor IMD performance at low signal levels a real life issue  or just something we see in the non real world of lab testing? So far the poor IMD at low signal levels does not seem to be a major issue amongst users of DDC based receivers. I am sure we would have heard by now it this wasn’t the case!
−	a number of modules. Each module is designed by an individual or	+
−	group and connects to other modules using a pre-defined and	+
−	common bus -- rather like plugging boards into a PC motherboard.	+
−	This modular approach enables prospective users to incorporate	+	So exactly what is happening when we expose a DDC to a band full of strong and weak signals and how should we make use of the dither facility of the
−	just the modules that interest them as well as designing their own	+	LT2208?
−	variants if desired. The approach also enables new ideas and	+
−	circuits to be tested by replacing an existing module. Since the	+
−	majority of modules will be retained, such experimentation can be	+
−	done with minimum disruption to an existing, working system.	+
−	The modules vary in complexity from simple band-pass filters and	+	== Test Introduction ==
−	input/output interfaces to full blown DSP functions. Such variety	+
−	enables experimenters with varying degrees of experience to	+
−	contribute. If you are interested in contributing, you are invited to	+
−	join in new or ongoing design, development and documentation	+
−	efforts.	+
−	The modules have each been named for easier identification when	+	What follows is an excellent evaluation of this effect by HB9AJG and is quite possibly the first time such comprehensive measurements have been made on an Amateur DDC receiver.
−	talking or writing about them. On the HPSDR website, each module	+
−	has its own web page. Some of the modules are being designed	+
−	so that they can be either used in conjunction with others or standalone.	+
−	Each module board size (except the Atlas backplane) is	+
−	typically 100mm by 120mm (optionally up to 220mm) and uses	+
−	either a 64 pin or 96 pin DIN41612 type connector.	+
−	== Accomplishments of the Project ==	+	There is an additional test that HB9AJG has done which is as follows. The LT2208 is a very small chip with one side of the device accepting uV signals (i.e. the input) and the other producing  3.3v digital signals (i.e. the digitally converted output). Stray capacitance across the chip + PCB, etc will mean that some of these digital signals will find their way to the input.
−	[[image:MOPA1.jpg|thumb|400px|Mile Stone Radio]]	+	This has the effect of raising the noise floor of the receiver and also introducing spurs at certain frequencies as the receiver is tuned.
−	Here is a photo of a complete Digital Up Conversion/Digital Down Conversion HPSDR transceiver by Phil Harman, VK6APH.  The modules are, from left to right - prototype Mercury DDC based on an LT2208 evaluation board and Ozy board - V2 Penelope DUC - Ozy controller board - all sitting on the Atlas bus.  Phil had the first QSO (2-way radio contact for the non-hams amongst us) with this on 7 October 2007 which coincided with his 40th anniversary of getting a Ham license!	+	The way that the LT2208 overcomes this problem is to scramble the digital output so the energy is dispersed over a wider band.  This is what the 'Random’ control in PowerSDR does.  The ADC output is first descrambled in the Mercury FPGA before processing further.
−	=== Block Diagram ===	+	I would have expected that the scrambler would have little effect on the IMD performance of Mercury. As we can see from the results this is not the
		+	case.
−	Here is a block diagram showing the Janus, Ozy, Mercury and Sasquatch modules and their functions.	+	I’d like to congratulate HP9AJG on an excellent series of measurements that go a long way to increasing our understanding as to how our new DDC receivers perform with real-world signals.
−	[[image:HPSDR_Block_10_Dec_2006.jpg|thumb|400px|]]	+
−	=== Module/Board Availability ===	+	Phil Harman, [[User:VK6APH|VK6APH]], 1 September 2009
−	Completely assembled and tested, parts kits, and/or bare boards may be available for each of the HPSDR projects on a limited basis.  See the FAQ section or individual wiki pages for what is available at the present time.  Generally, the boards, kits, or assemblies will be available for purchase through TAPR [http://tapr.org] and an indication of pre-production interest is gaged by a sign-up process located	+	==Test Setup==
−	at website http://www.hamsdr.com where one must register, log in, and use the "Projects" tab to get to any list.	+	<br />
		+	[[Image:MERCURY IM3DR 1.gif]]
−	=== Future Modules ===	+	Attenuation between generators: 74.8dB (terminated with 50 Ohms)<br />
		+	Attenuation from HP8640B to output: 36.2dB<br />
		+	Attenuation from HP8657A to output: 16.2dB
−	In order to provide a complete SDR transceiver other modules will be required. These include bandpass filters, a narrow band I/Q down converter to supplement the Mercury A/D converter, and low power transmitter functions etc.	+	This test setup was verified with an EK070 RX by Rohde+Schwarz from 80m to 10m, CW, 600Hz bandwidth:
−	There is still much to be done in bringing the HPSDR project to fruition. For those experimentally minded Amateurs, this may turn out to be the golden age of (software defined) radio!	+	:with it's 20dB input attenuator enabled, MDS was -114dBm
		+	::''at -13dBm input (each signal) no IM was audible, i.e IM3DR > 101dB''
		+	:without attenuator, MDS was -134dBm
		+	::''at -25dBm input (each signal) IM was audible, i.e IM3DR = 109dB (on 80m, 40m 15m, 10m)''
		+	::''at -30dBm input (each signal) IM was audible, i.e IM3DR = 104dB (on 20m)''
−	=== Open source design ===	+	So the test setup has an IM3DR of >101dB with inputs up to -13dBm, and an IM3DR of 104dBm at -30dBm for 20m, and an IM3DR of 109dBm at -25dBm for 80m, 40m, 15m, 10m.
−	'''Brief definition of Open Source'''	+	== MERCURY 3<sup>rd</sup> Order Intermodulation Free Dynamic Range IM3DR ==
−	In a "nutshell", open source is a term that is applied to a philosophy, in that the production and organization of a project or system is created through open and cooperative efforts.	+	May/June 2009/HB9AJG
−	Open source software refers to computer software available with its source code and under an "open source license" to study, change and improve its design and functionality.	+	Configuration:
		+	:Mercury v2.6, Ozy v1.2, Penny v1.1
		+	:'''''Dither & Random enabled''' (RX sensitivity reduced by 4dB)''
		+	:Clocks from Penelope
		+	:PowerSDR v1.10.4+BaseSVN 2025
		+	:PowerSDR RX-Meter calibrated to HP8657A
		+	:Bandwidth 48kHz, Buffer size 2048Bits
		+	:CWL, 500Hz
−	There are many "Open source software" licenses, the most prominent being the GNU General Public License (GNU GPL or simply GPL), originally written by Richard Stallman. The GPL grants the recipients of a computer program the following rights, or freedoms:	+	Lower frequency = HP8657A<br />
		+	Upper frequency = HP8640B<br />
		+	All dBm readings as displayed on the RX-Meter of PowerSDR (rounded to the next dB)<br />
		+	Signals 3dB above the Noise Floor are considered MDS.<br />
		+	Maximum input signals possible with this Test Setup: -13dBm
		+	:<nowiki>* =</nowiki> Artifacts from the ADC (very nonlinearly dependent on the input signals)
		+	:<nowiki>** =</nowiki> ADC Overload @ -20dBm
−	* The freedom to run the program, for any purpose.<br>	+	{| {{table}}
−	* The freedom to study how the program works, and modify it.<br>	+
−	* The freedom to redistribute copies.<br>	+
−	* The freedom to improve the program, and release the improvements to the public.<br>	+
−	The users are treated like co-developers, are encouraged to submit additions to the software, code fixes, bug reports, documentation etc. Having more co-developers increases the rate at which the software evolves. Furthermore, each end user's machine provides an additional testing environment. This new testing environment offers the ability to find and fix a new bug quickly.	+	| align="left" style="background:#f0f0f0;"|'''80m:  3680kHz + 3700kHz'''
−	[Note: this definition does not go into the various obligations and legalities and is intended to be brief and non-exhaustive.  The original was supplied by Kevin, M0KHZ and modified by the WikiSysOp.]	+	|-
−	This GPL philosophy extends to the hardware for this HPSDR cooperative project.  However it was felt by many that the software GPL and similar licenses would not adequately cover the hardware portion of this project, so an Open Hardware License (OHL) was devised.  Also, another license referred to as the NCL - Non-Commercial License, was implemented to take care of situation where the project developers wish to reserve commercial licensing rights.  The complete text of the two versions of the OHL/NCL licenses along with some explanation may be found on the TAPR website at http://www.tapr.org/ohl.html	+	| Preamp OFF:    Noise Floor = -115dBm
−	=== TAPR Affiliation ===	+	|-
−	In early June (2006) it was announced that agreement had been reached with TAPR http://tapr.org for TAPR to provide assistance and a "storefront" for the "products" of the HPSDR group.  TAPR has a long history of supporting various digital amateur radio related ventures.  We would encourage our members to become TAPR members, not only to support a worthy organization, but also to receive a member discount (usually around 10%) on their HPSDR and other purchases from them.	+	|
−	Assistance in project development is in the form of partial funding for alpha and beta runs of boards upon application to and approval by TAPR's Board of Directors, and then in guiding the manufacturing process.  It is not the intention of TAPR to profit from providing this assistance or the manufacture of projects.	+	|}
−	It should be emphasized that TAPR and HPSDR are independent organizations or communities and that any TAPR reproduction of HPSDR developed projects is through licensing agreements.	+	{| {{table}}
−	TAPR will be most likely the only source for HPSDR boards due to short runs and the investment required.  This does not preclude '''individuals''' having their '''own''' PCB boards made in keeping with the open-source philosophy.  Commercial reproduction may be restricted depending on the license granted by the board developers.  Visit the TAPR website http://tapr.org for current availability.	+	|-
−	=== AMSAT Affiliation ===	+	| width="77" height="13" valign="bottom" | Inputs each
−	In July (2006) the following announcement was made by Rick Hambly W2GPS, AMSAT President:	+	| width="47"  valign="bottom" | dBm
−	AMSAT will immediately initiate support for The High Performance Software	+	| width="47" align="center" valign="bottom" |
−	Defined Radio (HPSDR) project, an independent team that is dedicated to	+
−	bringing high performance software defined radio devices within the reach of	+
−	amateurs in terms of access to the hardware and software and at manageable	+
−	prices.	+
−		+
−	This is a rare opportunity for AMSAT to easily join a major technological	+
−	development and have a positive impact on both that development and AMSAT's	+
−	own primary interests. The High Performance Software Defined Radio (HPSDR)	+
−	project is a completely open source software (GNU Public License) and open	+
−	hardware design. It has an extremely capable group of core designers, many	+
−	of whom are also key AMSAT design team members, supported by a cast of	+
−	hundreds.	+
−		+
−	AMSAT will support HPSDR with a modest amount of financial, personnel and	+
−	other resources. Financial resources will be under AMSAT control and will be	+
−	used to support activities such as joint HPSDR and Eagle design meetings.	+
−	AMSAT's Engineering team will submit a 2007 budget for the AMSAT Board's	+
−	approval at the annual meeting in October. The modest resources that are	+
−	needed in 2006 can be provided by the Eagle team project.	+
−	=== Resources ===	+	| width="47" align="center" valign="bottom" |
−	Please be aware that we have a website with pages devoted to each sub-project plus other information and resources.  The website will not necessarily contain the latest information (that's the reason we have this wiki) but is a good starting place for a little less technical overview of the project and its parts.  The website is at http://openhpsdr.org  -- and the website also contains other information and links to many other references and resources of interest to the topics of Software Defined Radio, FPGA's, etc.	+	| width="47" align="center" valign="bottom" |
−	'''''For the very latest scoop, join the HPSDR discussion list (reflector).  You'll find information on the http://openhpsdr.org/reflector.html webpage on how to subscribe to this email list.'''''	+	| width="47" align="center" valign="bottom" | -15
−	We now also offer an alternative notification list (an announcement list) for those potential users not wanting the daily discussion list traffic.  Information on this HPSDR-announce list may also be found on the http://openhpsdr.org/reflector.html webpage.	+	| width="47" align="center" valign="bottom" | -20
−	Additional information can be found on the [http://openhpsdr.org/resources.html Resources] webpage this page has link to the relevant software being used for could be used with HPSDR boards and the  [http://openhpsdr.org/support.html Support] webpage has schematic and production documents for the boards that have been produced.	+	| width="47" align="center" valign="bottom" | -30
−	TAPR/HPSDR ordering page: http://tapr.org/kits.html	+	| width="47" align="center" valign="bottom" | -40
−	== Wiki Sysop ==	+	| width="47" align="center" valign="bottom" | -50
−	Please contact KV0S (the "Wiki Sysop") for information or help. Contact may be made via email: "kv0s" at "openhpsdr" dot "org"	+	| width="47" align="center" valign="bottom" | -60
−	== Go to the [[HPSDRWiki:Community Portal|Community Portal]] for project information ==	+	| width="47" align="center" valign="bottom" | -70
−	[[HpsdrWiki:Community Portal|Community Portal]]	+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -112*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 96.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 52.5
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -134dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -108
		+
		+	| align="center" valign="bottom" | -125
		+
		+	| align="center" valign="bottom" | -125
		+
		+	| align="center" valign="bottom" | -131
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -134*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -108
		+
		+	| align="center" valign="bottom" | -128
		+
		+	| align="center" valign="bottom" | -126
		+
		+	| align="center" valign="bottom" | -132
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -134*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 88
		+
		+	| align="center" valign="bottom" | 101.5
		+
		+	| align="center" valign="bottom" | 95.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 96.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 64
		+
		+	| align="center" valign="bottom" | 52
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''40m:  7000kHz + 7020kHz'''
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -115dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -109
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 95.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 54
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -134dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -111
		+
		+	| align="center" valign="bottom" | -127
		+
		+	| align="center" valign="bottom" | -123
		+
		+	| align="center" valign="bottom" | -130
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -109
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -126
		+
		+	| align="center" valign="bottom" | -133
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 90
		+
		+	| align="center" valign="bottom" | 102
		+
		+	| align="center" valign="bottom" | 94.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 96.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''20m:  14080kHz + 14100kHz'''
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -114dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 98.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -134dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -21**
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -116
		+
		+	| align="center" valign="bottom" | -125
		+
		+	| align="center" valign="bottom" | -126
		+
		+	| align="center" valign="bottom" | -131
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -125
		+
		+	| align="center" valign="bottom" | -123
		+
		+	| align="center" valign="bottom" | -134
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 93
		+
		+	| align="center" valign="bottom" | 100
		+
		+	| align="center" valign="bottom" | 94.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 97.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''15m:  21080kHz + 21100kHz'''
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -114dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -112*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -106
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -114*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -112*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 91.5
		+
		+	| align="center" valign="bottom" | 93.5
		+
		+	| align="center" valign="bottom" | 84
		+
		+	| align="center" valign="bottom" | 73.5
		+
		+	| align="center" valign="bottom" | 63
		+
		+	| align="center" valign="bottom" | 52
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13" valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -133dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -21**
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" | -104
		+
		+	| align="center" valign="bottom" | -115
		+
		+	| align="center" valign="bottom" | -122
		+
		+	| align="center" valign="bottom" | -129
		+
		+	| align="center" valign="bottom" | -133*
		+
		+	| align="center" valign="bottom" | -133*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -103
		+
		+	| align="center" valign="bottom" | -116
		+
		+	| align="center" valign="bottom" | -120
		+
		+	| align="center" valign="bottom" | -130
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -131*
		+
		+	| align="center" valign="bottom" | -131*
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 82.5
		+
		+	| align="center" valign="bottom" | 90.5
		+
		+	| align="center" valign="bottom" | 91
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 94.5
		+
		+	| align="center" valign="bottom" | -93
		+
		+	| align="center" valign="bottom" | 82.5
		+
		+	| align="center" valign="bottom" | 71.5
		+
		+	| align="center" valign="bottom" | 61.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''10m:  28080kHz + 28100kHz'''
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -113dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -111*
		+
		+	| align="center" valign="bottom" | -110*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -113*
		+
		+	| align="center" valign="bottom" | -112*
		+
		+	| align="center" valign="bottom" | -111*
		+
		+	| align="center" valign="bottom" | -110*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 92
		+
		+	| align="center" valign="bottom" | 93
		+
		+	| align="center" valign="bottom" | 83
		+
		+	| align="center" valign="bottom" | 72.5
		+
		+	| align="center" valign="bottom" | 61
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 50
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -134dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -21**
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -108
		+
		+	| align="center" valign="bottom" | -120
		+
		+	| align="center" valign="bottom" | -131
		+
		+	| align="center" valign="bottom" | -131*
		+
		+	| align="center" valign="bottom" | -128*
		+
		+	| align="center" valign="bottom" | -128*
		+
		+	| align="center" valign="bottom" | -128*
		+
		+	| align="center" valign="bottom" | -128*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -120
		+
		+	| align="center" valign="bottom" | -134
		+
		+	| align="center" valign="bottom" | -134*
		+
		+	| align="center" valign="bottom" | -131*
		+
		+	| align="center" valign="bottom" | -131*
		+
		+	| align="center" valign="bottom" | -129*
		+
		+	| align="center" valign="bottom" | -129*
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 74.5
		+
		+	| align="center" valign="bottom" | 82.5
		+
		+	| align="center" valign="bottom" | 90
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 97.5
		+
		+	| align="center" valign="bottom" | 92.5
		+
		+	| align="center" valign="bottom" | 79.5
		+
		+	| align="center" valign="bottom" | 69.5
		+
		+	| align="center" valign="bottom" | 58.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 48.5
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''6m:  49080kHz + 49100kHz'''
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -113dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -111
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 81
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 89
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| Preamp ON:    Noise Floor = -133dBm
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" | -21**
		+
		+	| width="47" align="center" valign="bottom" | -25
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -35
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	| width="47" align="center" valign="bottom" | -80
		+
		+	| width="47" align="center" valign="bottom" | -90
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" | -76
		+
		+	| align="center" valign="bottom" | -89
		+
		+	| align="center" valign="bottom" | -104
		+
		+	| align="center" valign="bottom" | -120
		+
		+	| align="center" valign="bottom" | -131
		+
		+	| align="center" valign="bottom" | -130*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" | -75
		+
		+	| align="center" valign="bottom" | -88
		+
		+	| align="center" valign="bottom" | -103
		+
		+	| align="center" valign="bottom" | -118
		+
		+	| align="center" valign="bottom" | -127
		+
		+	| align="center" valign="bottom" | -130*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -132*
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" | 54.5
		+
		+	| align="center" valign="bottom" | 63.5
		+
		+	| align="center" valign="bottom" | 73.5
		+
		+	| align="center" valign="bottom" | 84
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 89
		+
		+	| align="center" valign="bottom" | 80
		+
		+	| align="center" valign="bottom" | 72
		+
		+	| align="center" valign="bottom" | 62
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	== Effect of "Dither" and "Random" ==
		+	(August 2009 / HB9AJG)
		+
		+	Even slight imperfections of the ADC transfer curve will result in unwanted signals. The '''Dither''' signal random­izes the location of the input signal on the ADC transfer curve, resulting in an improved IMD perform­ance. Part of the Dither signal will leak through to the output, causing a rise of the noise floor.
		+
		+	Due to the small size of the ADC, and depending on the PCB layout, coupling from the output to the input may occur. The '''Random''' signal is to prevent such interferences from appearing as regular spectral lines. So it would not be expected to have much effect on the IMD performance.
		+
		+	'''The tests below show that both signals are required to achieve the best IM3DR.'''
		+
		+	IM3 signals 3db above the noise floor are considered MDS.
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''80m:  3680kHz + 3700kHz, Preamp OFF'''
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Dither enabled,
		+
		+	|style="font-weight:bold" valign="bottom" | Random enabled:
		+
		+	| valign="bottom" | Noise Floor = -115dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 96
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 52
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Dither enabled,
		+
		+	|style="font-style:Italic" valign="bottom" | Random disabled:
		+
		+	| valign="bottom" | Noise Floor = -115dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -102
		+
		+	| align="center" valign="bottom" | -102
		+
		+	| align="center" valign="bottom" | -99
		+
		+	| align="center" valign="bottom" | -99
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -110
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -103
		+
		+	| align="center" valign="bottom" | -104
		+
		+	| align="center" valign="bottom" | -99
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -110
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 87.5
		+
		+	| align="center" valign="bottom" | 83
		+
		+	| align="center" valign="bottom" | 69
		+
		+	| align="center" valign="bottom" | 59.5
		+
		+	| align="center" valign="bottom" | 48
		+
		+	| align="center" valign="bottom" | 37.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 40
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-style:Italic" height="13" valign="bottom" | Dither disabled,
		+
		+	|style="font-weight:bold"  valign="bottom" | Random enabled:
		+
		+	| valign="bottom" | Noise Floor = -118dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -106
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -102
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -107
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -102
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 93
		+
		+	| align="center" valign="bottom" | 88.5
		+
		+	| align="center" valign="bottom" | 68
		+
		+	| align="center" valign="bottom" | 62
		+
		+	| align="center" valign="bottom" | 61
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 53.5
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-style:Italic" height="13" valign="bottom" | Dither disabled,
		+
		+	|style="font-style:Italic" valign="bottom" | Random disabled:
		+
		+	| valign="bottom" | Noise Floor = -118dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -101
		+
		+	| align="center" valign="bottom" | -105
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -104
		+
		+	| align="center" valign="bottom" | -106
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -101
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 87.5
		+
		+	| align="center" valign="bottom" | 85.5
		+
		+	| align="center" valign="bottom" | 64.5
		+
		+	| align="center" valign="bottom" | 57
		+
		+	| align="center" valign="bottom" | 50.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 53.5
		+
		+	| align="center" valign="bottom" | 46
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''20m:  14080kHz + 14100kHz, Preamp OFF'''
		+
		+	|-
		+
		+	|
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Dither enabled,
		+
		+	|style="font-weight:bold" valign="bottom" | Random enabled:
		+
		+	| valign="bottom" | Noise Floor = -114dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 98.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 52.5
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Dither enabled,
		+
		+	|style="font-style:Italic" valign="bottom" | Random disabled:
		+
		+	| valign="bottom" | Noise Floor = -115dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -90
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -99
		+
		+	| align="center" valign="bottom" | -114
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -93
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -114
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 82
		+
		+	| align="center" valign="bottom" | 76.5
		+
		+	| align="center" valign="bottom" | 63.5
		+
		+	| align="center" valign="bottom" | 51
		+
		+	| align="center" valign="bottom" | 42.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 39.5
		+
		+	| align="center" valign="bottom" | 44
		+
		+	|-
		+
		+	|style="font-size:11pt" height="14"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-style:Italic" height="13" valign="bottom" | Dither disabled,
		+
		+	|style="font-weight:bold"  valign="bottom" | Random enabled:
		+
		+	| valign="bottom" | Noise Floor = -117dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -105
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -111
		+
		+	| align="center" valign="bottom" | -115
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -108
		+
		+	| align="center" valign="bottom" | -111
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -99
		+
		+	| align="center" valign="bottom" | -110
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 91.5
		+
		+	| align="center" valign="bottom" | 92.5
		+
		+	| align="center" valign="bottom" | 66.5
		+
		+	| align="center" valign="bottom" | 59.5
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 60.5
		+
		+	| align="center" valign="bottom" | 54.5
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-size:11pt" height="14"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	|style="font-style:Italic" height="13" valign="bottom" | Dither disabled,
		+
		+	|style="font-style:Italic" valign="bottom" | Random disabled:
		+
		+	| valign="bottom" | Noise Floor = -118dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -97
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -91
		+
		+	| align="center" valign="bottom" | -91
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | 81.5
		+
		+	| align="center" valign="bottom" | 76
		+
		+	| align="center" valign="bottom" | 62.5
		+
		+	| align="center" valign="bottom" | 51.5
		+
		+	| align="center" valign="bottom" | 45
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 40
		+
		+	| align="center" valign="bottom" | 46
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+	== MERCURY IM3DR with a third signal present ==
		+	(May/June 2009/ HB9AJG)
		+
		+	In his presentation on the design of MERCURY at the ARRL/TAPR Conference on Digital Communications 2008 Phil Harman explains that other strong signals have the same effect as "Dither enabled". To verify this, a second coupler and a third signal generator were added to the Test Setup:
		+
		+	[[Image:MERCURY IM3DR 2.gif]]
		+
		+	''"Dither" and "Random" were disabled'', and the measurements on '''20m''' were repeated:
		+	<!-- Begin table 5a -->
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''20m:  14080kHz + 14100kHz'''
		+
		+	|-
		+
		+	| style="font-style:Italic" valign="bottom" | Random disabled and Dither disabled
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -118dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" valign="bottom" |
		+
		+	| width="47"  valign="bottom" |
		+
		+	| width="47"  valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	|-
		+
		+	|style="font-weight:bold" height="6" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	| style="font-weight:bold" valign="bottom" height="13" | No third signal
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | IM @ - ∆f
		+
		+	| width="57"  valign="bottom" | dBm
		+
		+	| width="35" valign="bottom" |
		+
		+	| width="47"  valign="bottom" |
		+
		+	| width="47"  valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -97
		+
		+	| width="47" align="center" valign="bottom" | -94
		+
		+	| width="47" align="center" valign="bottom" | -91
		+
		+	| width="47" align="center" valign="bottom" | -91
		+
		+	| width="47" align="center" valign="bottom" | -95
		+
		+	| width="47" align="center" valign="bottom" | -100
		+
		+	| width="47" align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" | -96
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -95
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -116
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 40
		+
		+	| align="center" valign="bottom" | 46
		+
		+	|-
		+
		+	|style="font-weight:bold" height="6" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Third signal
		+
		+	|style="font-weight:bold"  valign="bottom" | -52dBm*
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -91
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -100
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 50
		+
		+	| align="center" valign="bottom" | 54
		+
		+	| align="center" valign="bottom" |
		+
		+	|- style="font-size:6pt"
		+
		+	|style="font-weight:bold" height="8" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Third signal
		+
		+	|style="font-weight:bold"  valign="bottom" | -47dBm*
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -92
		+
		+	| align="center" valign="bottom" | -93
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -98
		+
		+	| align="center" valign="bottom" | -93
		+
		+	| align="center" valign="bottom" | -94
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 53
		+
		+	| align="center" valign="bottom" | 64
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="6" valign="bottom" |
		+
		+	|style="font-weight:bold"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | Third signal
		+
		+	|style="font-weight:bold"  valign="bottom" | -14dBm*
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -112
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 82
		+
		+	| align="center" valign="bottom" | 74
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+
		+	<!-- End table 5a -->
		+	'''Frequency of the third signal:''' anywhere between 1 and 30MHz (except harmonics and IMs)
		+
		+	'''*Approximate signal level, the limit is fuzzy: at levels up to about 10dB higher IM signals vary between nil and MDS
		+
		+
		+	With very strong third signals (S9+60dB), an improvement of the IM3DR of approximately 30db is achieved.
		+
		+	However, this is not as much as with "Dither" ''and'' "Random" enabled (copy from above):
		+
		+	{| {{table}}
		+
		+	| align="left" style="background:#f0f0f0;"|'''20m:  14080kHz + 14100kHz'''
		+
		+	|-
		+
		+	|style="font-style:Italic" valign="bottom" | Random enabled and Dither enabled
		+
		+	|-
		+
		+	| Preamp OFF:    Noise Floor = -114dBm
		+
		+	|}
		+
		+	{| {{table}}
		+
		+	|-
		+
		+	| width="77" height="13" valign="bottom" | Inputs each
		+
		+	| width="47"  valign="bottom" | dBm
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" |
		+
		+	| width="47" align="center" valign="bottom" | -15
		+
		+	| width="47" align="center" valign="bottom" | -20
		+
		+	| width="47" align="center" valign="bottom" | -30
		+
		+	| width="47" align="center" valign="bottom" | -40
		+
		+	| width="47" align="center" valign="bottom" | -50
		+
		+	| width="47" align="center" valign="bottom" | -60
		+
		+	| width="47" align="center" valign="bottom" | -70
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ - ∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -113
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	| height="13" valign="bottom" | IM @ +∆f
		+
		+	|  valign="bottom" | dBm
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" | -114
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	| align="center" valign="bottom" | -
		+
		+	|-
		+
		+	|style="font-weight:bold" height="13" valign="bottom" | IM3DR
		+
		+	|style="font-weight:bold"  valign="bottom" | dB
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|style="font-weight:bold" align="center" valign="bottom" | 98.5
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|-
		+
		+	| height="13"  valign="bottom" |
		+
		+	|  valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	| align="center" valign="bottom" |
		+
		+	|}
		+
		+
		+	'''Now, of course, the next step was to connect my DX-88 8-band trap vertical instead of the third signal generator '''(no filters between antenna and Mercury):
		+
		+	<!-- Begin table 5c -->
		+	{| {{table}}
		+	|style="font-style:Italic" valign="bottom" | Random disabled and Dither disabled
		+	|}
		+	{| {{table}}
		+	|- style="font-size:9pt;font-weight:bold" align="center" valign="top" style="background:#f0f0f0"
		+	| width="42" height="24" | Band
		+	| width="53" | Preamp
		+	| width="64" | Noise floor
		+	| width="42" | UTC
		+	| width="85" | max gen level<br />for IM3 < MDS
		+	| width="146" | Comment
		+	| width="47" | IM3DR
		+	|-  align="center" valign="bottom"
		+	| height="13" | 20m
		+	| OFF
		+	| -114dBm
		+	| 15:30
		+	| -50 dBm
		+	| varies slightly with time
		+	| 64dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -115dBm
		+	|
		+	| -41dBm
		+	| (fading effects?)
		+	| 74dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|-  align="center" valign="bottom"
		+	| height="13" | 40m
		+	| OFF
		+	| -108dBm
		+	| 16:0
		+	| -40 dBm
		+	| varies slightly
		+	| 68dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -108dBm
		+	|
		+	| -24dBm
		+	|
		+	| 84dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|-  align="center" valign="bottom"
		+	| height="13" | 80m
		+	| OFF
		+	| -97dBm
		+	| 16:10
		+	| -34 dBm
		+	| varies slightly
		+	| 63dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -97dBm
		+	|
		+	| -22dBm
		+	| just before ADC Overload!
		+	| 75dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|-  align="center" valign="bottom"
		+	| height="13" | 15m
		+	| OFF
		+	| -114dBm
		+	| 16:20
		+	| -46 dBm
		+	| varies by several dB
		+	| 68dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -116dBm
		+	|
		+	| -40dBm
		+	|
		+	| 76dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|-  align="center" valign="bottom"
		+	| height="13" | 10m
		+	| OFF
		+	| -116dBm
		+	| 16:30
		+	| -47 dBm
		+	| varies by several dB
		+	| 69dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -123dBm
		+	|
		+	| -45dBm
		+	|
		+	| 78dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|
		+	|-  align="center" valign="bottom"
		+	| height="13" |  6m
		+	| OFF
		+	| -118dBm
		+	| 16:40
		+	| -46 dBm
		+	| varies slightly
		+	| 72dB
		+	|-  align="center" valign="bottom"
		+	| height="13" |
		+	| ON
		+	| -136dBm
		+	|
		+	| -50dBm
		+	|
		+	| 86dB
		+	|-
		+	|style="font-weight:bold" height="13" valign="bottom" |
		+	|style="font-weight:bold" valign="bottom" |
		+	|  valign="bottom" |
		+	|  valign="bottom" |
		+	|  valign="bottom" |
		+	|  valign="bottom" |
		+	|  valign="bottom" |
		+	|}
		+	<!-- End table 5c -->
		+
		+	==CONCLUSION==
		+
		+	The antenna has about the same effect as a third signal generator. Enabling "Dither" and "Random" results in a much higher IM3DR, however. Therefore, I think if a band is heavily congest­ed, it is preferable to enable "Dither" and "Random" and to accept the degradation of sensitivity of 4dB.'''
		+
		+	[[Category:Mercury]]

---

Latest revision as of 10:45, 25 January 2010

The use by Amateurs of receivers that use Digital Down Conversion (DDC), where the antenna is effectively connected directly to an Analogue to Digital Converter (ADC), is relatively new.

DDC based receivers perform differently to conventional analogue receiver particularly when intermodulation (IMD) testing is performed. Unlike an analogue receiver the IMD varies with the level of input signals. This renders the value of conventional 3rd order intercept (IP3) meaningless.

The reason for the variation of IP3 with signal level is that for small input signals only a small number of the available ADC bits are actually used. Also since these are near the origin of the ADC transfer curve there are often imperfections that degrade the IP3 performance.

We can reduce the effect of the limited number of bits and ADC non-linearity by deliberately adding additional signal(s) into the input of the ADC such that our low level signals are added to the (larger) additional signal(s). In effect the larger signal sweeps our small signal over a wider portion of the ADC transfer curve. This means that our combined signal spends less time over any non-linear portions and also uses more ADC bits.

You can perhaps think of the additional signal giving the small signal a ‘piggy back ride’ across the ADC transfer curve.

As long as the instantaneous sum of the additional signal(s) and our wanted signal does not overload our ADC then the overall effect is beneficial.

So here is a significant difference between our existing analogue receivers and a DDC based receiver. In the former case we go to a lot of trouble to keep large out of band signals out of the input of the receiver. In the latter case, up to a certain level, they actually are an advantage!

The additional signal(s) can come from a number of sources. The LT2208 ADC that is used in Mercury has the facility to inject pseudo random noise into its input. This noise can then be subtracted at the output. This technique is known as ‘dithering’.

By subtracting the noise at the output of the ADC we only degrade the overall signal to noise ratio of the ADC by a few dB. Alternatively, we could inject an out-of-band signal into the antenna socket and use this as a source of dithering. Or perhaps there are enough strong signals already present at the input of the ADC to perform the dithering function so there is no need to either inject random noise or a specific out of band signal.

So is the effect of poor IMD performance at low signal levels a real life issue or just something we see in the non real world of lab testing? So far the poor IMD at low signal levels does not seem to be a major issue amongst users of DDC based receivers. I am sure we would have heard by now it this wasn’t the case!

So exactly what is happening when we expose a DDC to a band full of strong and weak signals and how should we make use of the dither facility of the LT2208?

Test Introduction

What follows is an excellent evaluation of this effect by HB9AJG and is quite possibly the first time such comprehensive measurements have been made on an Amateur DDC receiver.

There is an additional test that HB9AJG has done which is as follows. The LT2208 is a very small chip with one side of the device accepting uV signals (i.e. the input) and the other producing 3.3v digital signals (i.e. the digitally converted output). Stray capacitance across the chip + PCB, etc will mean that some of these digital signals will find their way to the input.

This has the effect of raising the noise floor of the receiver and also introducing spurs at certain frequencies as the receiver is tuned.

The way that the LT2208 overcomes this problem is to scramble the digital output so the energy is dispersed over a wider band. This is what the 'Random’ control in PowerSDR does. The ADC output is first descrambled in the Mercury FPGA before processing further.

I would have expected that the scrambler would have little effect on the IMD performance of Mercury. As we can see from the results this is not the case.

I’d like to congratulate HP9AJG on an excellent series of measurements that go a long way to increasing our understanding as to how our new DDC receivers perform with real-world signals.

Phil Harman, VK6APH, 1 September 2009

Test Setup

Attenuation between generators: 74.8dB (terminated with 50 Ohms)
Attenuation from HP8640B to output: 36.2dB
Attenuation from HP8657A to output: 16.2dB

This test setup was verified with an EK070 RX by Rohde+Schwarz from 80m to 10m, CW, 600Hz bandwidth:

with it's 20dB input attenuator enabled, MDS was -114dBm

at -13dBm input (each signal) no IM was audible, i.e IM3DR > 101dB

without attenuator, MDS was -134dBm

at -25dBm input (each signal) IM was audible, i.e IM3DR = 109dB (on 80m, 40m 15m, 10m)

at -30dBm input (each signal) IM was audible, i.e IM3DR = 104dB (on 20m)

So the test setup has an IM3DR of >101dB with inputs up to -13dBm, and an IM3DR of 104dBm at -30dBm for 20m, and an IM3DR of 109dBm at -25dBm for 80m, 40m, 15m, 10m.

MERCURY 3^rd Order Intermodulation Free Dynamic Range IM3DR

May/June 2009/HB9AJG

Configuration:

Mercury v2.6, Ozy v1.2, Penny v1.1

Dither & Random enabled (RX sensitivity reduced by 4dB)

Clocks from Penelope

PowerSDR v1.10.4+BaseSVN 2025

PowerSDR RX-Meter calibrated to HP8657A

Bandwidth 48kHz, Buffer size 2048Bits

CWL, 500Hz

Lower frequency = HP8657A
Upper frequency = HP8640B
All dBm readings as displayed on the RX-Meter of PowerSDR (rounded to the next dB)
Signals 3dB above the Noise Floor are considered MDS.
Maximum input signals possible with this Test Setup: -13dBm

* = Artifacts from the ADC (very nonlinearly dependent on the input signals)

** = ADC Overload @ -20dBm

80m: 3680kHz + 3700kHz

Preamp OFF: Noise Floor = -115dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-110	-	-	-	-	-112*	-
IM @ +∆f	dBm				-113	-	-	-	-	-113*	-
IM3DR	dB				96.5					52.5

Preamp ON: Noise Floor = -134dBm

Inputs each	dBm	-20	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f	dBm	-108	-125	-125	-131	-	-	-	-134*	-132*	-
IM @ +∆f	dBm	-108	-128	-126	-132	-	-	-	-134*	-132*	-
IM3DR	dB	88	101.5	95.5	96.5				64	52

40m: 7000kHz + 7020kHz

Preamp OFF: Noise Floor = -115dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-109	-	-	-	-	-114*	-
IM @ +∆f	dBm				-112	-	-	-	-	-114*	-
IM3DR	dB				95.5					54

Preamp ON: Noise Floor = -134dBm

Inputs each	dBm	-20	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f	dBm	-111	-127	-123	-130	-	-	-	-	-	-
IM @ +∆f	dBm	-109	-	-126	-133	-	-	-	-	-	-
IM3DR	dB	90	102	94.5	96.5

20m: 14080kHz + 14100kHz

Preamp OFF: Noise Floor = -114dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-113	-	-	-	-	-	-
IM @ +∆f	dBm				-114	-	-	-	-	-	-
IM3DR	dB				98.5

Preamp ON: Noise Floor = -134dBm

Inputs each	dBm	-21**	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f	dBm	-116	-125	-126	-131	-	-	-	-	-	-
IM @ +∆f	dBm	-112	-125	-123	-134	-	-	-	-	-	-
IM3DR	dB	93	100	94.5	97.5

15m: 21080kHz + 21100kHz

Preamp OFF: Noise Floor = -114dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f					-107	-113*	-114*	-113*	-113*	-112*	-
IM @ +∆f	dBm				-106	-114*	-114*	-114*	-113*	-112*	-
IM3DR	dB				91.5	93.5	84	73.5	63	52

Preamp ON: Noise Floor = -133dBm

Inputs each	dBm	-21**	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f		-104	-115	-122	-129	-133*	-133*	-132*	-132*	-
IM @ +∆f	dBm	-103	-116	-120	-130		-132*	-131*	-131*	-
IM3DR	dB	82.5	90.5	91	94.5	-93	82.5	71.5	61.5

10m: 28080kHz + 28100kHz

Preamp OFF: Noise Floor = -113dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f					-107	-113*	-113*	-113*	-111*	-110*	-
IM @ +∆f	dBm				-107	-113*	-113*	-112*	-111*	-110*	-
IM3DR	dB				92	93	83	72.5	61	50

Preamp ON: Noise Floor = -134dBm

Inputs each	dBm	-21**	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f		-96	-108	-120	-131	-131*	-128*	-128*	-128*	-128*	-
IM @ +∆f	dBm	-95	-107	-120	-134	-134*	-131*	-131*	-129*	-129*	-
IM3DR	dB	74.5	82.5	90	97.5	92.5	79.5	69.5	58.5	48.5

6m: 49080kHz + 49100kHz

Preamp OFF: Noise Floor = -113dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f					-97	-111	-	-	-	-	-
IM @ +∆f	dBm				-95	-107	-	-	-	-	-
IM3DR	dB				81	89

Preamp ON: Noise Floor = -133dBm

Inputs each	dBm	-21**	-25	-30	-35	-40	-50	-60	-70	-80	-90
IM @ - ∆f		-76	-89	-104	-120	-131	-130*	-132*	-132*	-	-
IM @ +∆f	dBm	-75	-88	-103	-118	-127	-130*	-132*	-132*	-	-
IM3DR	dB	54.5	63.5	73.5	84	89	80	72	62

Effect of "Dither" and "Random"

(August 2009 / HB9AJG)

Even slight imperfections of the ADC transfer curve will result in unwanted signals. The Dither signal random­izes the location of the input signal on the ADC transfer curve, resulting in an improved IMD perform­ance. Part of the Dither signal will leak through to the output, causing a rise of the noise floor.

Due to the small size of the ADC, and depending on the PCB layout, coupling from the output to the input may occur. The Random signal is to prevent such interferences from appearing as regular spectral lines. So it would not be expected to have much effect on the IMD performance.

The tests below show that both signals are required to achieve the best IM3DR.

IM3 signals 3db above the noise floor are considered MDS.

80m: 3680kHz + 3700kHz, Preamp OFF

Dither enabled,

Random enabled:

Noise Floor = -115dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-110	-	-	-	-	-112	-
IM @ +∆f	dBm				-112	-	-	-	-	-112	-
IM3DR	dB				96					52

Dither enabled,

Random disabled:

Noise Floor = -115dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-102	-102	-99	-99	-98	-98	-110
IM @ +∆f	dBm				-103	-104	-99	-100	-98	-97	-110
IM3DR	dB				87.5	83	69	59.5	48	37.5	40

Dither disabled,

Random enabled:

Noise Floor = -118dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-106	-110	-98	-102	-112	-113	-
IM @ +∆f	dBm				-110	-107	-98	-102	-110	-114	-
IM3DR	dB				93	88.5	68	62	61	53.5

Dither disabled,

Random disabled:

Noise Floor = -118dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-101	-105	-94	-97	-100	-113	-116
IM @ +∆f	dBm				-104	-106	-95	-97	-101	-114	-116
IM3DR	dB				87.5	85.5	64.5	57	50.5	53.5	46

20m: 14080kHz + 14100kHz, Preamp OFF

Dither enabled,

Random enabled:

Noise Floor = -114dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-113	-	-	-	-	-112	-
IM @ +∆f	dBm				-114	-	-	-	-	-113	-
IM3DR	dB				98.5					52.5

Dither enabled,

Random disabled:

Noise Floor = -115dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-96	-96	-92	-90	-92	-99	-114
IM @ +∆f	dBm				-98	-97	-95	-92	-93	-100	-114
IM3DR	dB				82	76.5	63.5	51	42.5	39.5	44

Dither disabled,

Random enabled:

Noise Floor = -117dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-105	-114	-96	-100	-111	-115	-
IM @ +∆f	dBm				-108	-111	-97	-99	-110	-114	-
IM3DR	dB				91.5	92.5	66.5	59.5	60.5	54.5

Dither disabled,

Random disabled:

Noise Floor = -118dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-97	-94	-91	-91	-95	-100	-116
IM @ +∆f	dBm				-96	-98	-94	-92	-95	-100	-116
IM3DR	dB				81.5	76	62.5	51.5	45	40	46

MERCURY IM3DR with a third signal present

(May/June 2009/ HB9AJG)

In his presentation on the design of MERCURY at the ARRL/TAPR Conference on Digital Communications 2008 Phil Harman explains that other strong signals have the same effect as "Dither enabled". To verify this, a second coupler and a third signal generator were added to the Test Setup:

"Dither" and "Random" were disabled, and the measurements on 20m were repeated:

20m: 14080kHz + 14100kHz

Random disabled and Dither disabled

Preamp OFF: Noise Floor = -118dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70

No third signal

IM @ - ∆f	dBm				-97	-94	-91	-91	-95	-100	-116
IM @ +∆f	dBm				-96	-98	-94	-92	-95	-100	-116
IM3DR	dB									40	46
Third signal	-52dBm*
IM @ - ∆f	dBm					-94	-91	-92	-100	-114	-
IM @ +∆f	dBm					-98	-94	-92	-100	-114	-
IM3DR	dB								50	54
Third signal	-47dBm*
IM @ - ∆f	dBm					-94	-92	-93	-114	-	-
IM @ +∆f	dBm					-98	-93	-94	-114	-	-
IM3DR	dB							53	64
Third signal	-14dBm*
IM @ - ∆f	dBm					-112	-112	-114	-	-	-
IM @ +∆f	dBm					-112	-112	-114	-	-	-
IM3DR	dB						82	74

Frequency of the third signal: anywhere between 1 and 30MHz (except harmonics and IMs)

*Approximate signal level, the limit is fuzzy: at levels up to about 10dB higher IM signals vary between nil and MDS

With very strong third signals (S9+60dB), an improvement of the IM3DR of approximately 30db is achieved.

However, this is not as much as with "Dither" and "Random" enabled (copy from above):

20m: 14080kHz + 14100kHz

Random enabled and Dither enabled

Preamp OFF: Noise Floor = -114dBm

Inputs each	dBm				-15	-20	-30	-40	-50	-60	-70
IM @ - ∆f	dBm				-113	-	-	-	-	-	-
IM @ +∆f	dBm				-114	-	-	-	-	-	-
IM3DR	dB				98.5

Now, of course, the next step was to connect my DX-88 8-band trap vertical instead of the third signal generator (no filters between antenna and Mercury):

Random disabled and Dither disabled

Band	Preamp	Noise floor	UTC	max gen level for IM3 < MDS	Comment	IM3DR
20m	OFF	-114dBm	15:30	-50 dBm	varies slightly with time	64dB
	ON	-115dBm		-41dBm	(fading effects?)	74dB
40m	OFF	-108dBm	16:0	-40 dBm	varies slightly	68dB
	ON	-108dBm		-24dBm		84dB
80m	OFF	-97dBm	16:10	-34 dBm	varies slightly	63dB
	ON	-97dBm		-22dBm	just before ADC Overload!	75dB
15m	OFF	-114dBm	16:20	-46 dBm	varies by several dB	68dB
	ON	-116dBm		-40dBm		76dB
10m	OFF	-116dBm	16:30	-47 dBm	varies by several dB	69dB
	ON	-123dBm		-45dBm		78dB
6m	OFF	-118dBm	16:40	-46 dBm	varies slightly	72dB
	ON	-136dBm		-50dBm		86dB

CONCLUSION

The antenna has about the same effect as a third signal generator. Enabling "Dither" and "Random" results in a much higher IM3DR, however. Therefore, I think if a band is heavily congest­ed, it is preferable to enable "Dither" and "Random" and to accept the degradation of sensitivity of 4dB.