Hello Leon!The 16 bit fixed point DSP chip could be an issue which is dependent on how it is used. Dealing with fixed point is an art few can master. I did it with the AEA DSP boxes 15 years ago because there was no other choice and I am doing it now in FPGA and some smaller spacecraft embedded microsystems. I am uncertain about its suitability for general experimentation with the goal of a high performance SDR. If it were a 32 bit fixed point system, we would be in business. The FPGA seems nice enough. The USRP uses Cyclone with 20,000-ish logical elements. This has 50K. So that is a win plus it has the 18x18 multipliers. All positives. It is my personal opinion that we are better served at this time by mostly avoiding the use of DSP chips, especially fixed point ones and to rely on our ability to speedily process data on our modern desktops. The SDR-1000 DSP core, written by AB2KT and I, recently was hung on the end of an Agilent multi receiver system. It successfully prosecuted 92 separate receivers, each sending I/Q at 8000 samples per second, simultaneously on a 2.4 GHz Xeon based Dell Server. The processor was not sweating at all. It will easily do this up to 48000 samples per second since we were not consuming 1/6 of the CPU resources.
I went to Reno to work with the Gnu Radio folks for a week. Using the GnuRadio software elements, plus some blocks I helped write, we implemented a 1 Mbps GMSK packet SYSTEM that transfers data over USB 2.0 (the preferred medium unless you can demonstrate WHY you must have firewire) and we did it from scratch in 3 days . You may download that software now from GnuRadio. This ran successfully on the N2MJI (USRP hardware designer) abacus, a 1.8 GHz celeron laptop. We do need to stop underestimating these desktops and to learn how to optimize for them because they are so much easier to deal with than DSP chips. DSP chips are your last resort and intended primarily for embedded systems that must have them. I would limit there use to those places where I need a completely standalone device and could afford to hang an external system on the SDR.
The nice thing about using the FX2 and USB 2.0, is that we can and should adapt our toy to use the HUGE body of software that GnuRadio has produced in addition to those things we can and should add.
73's Bob N4HY Leon Heller wrote:
Here is an interesting product with a TI DSP, Spartan 3 FPGA and Firewire: http://www.traquair.com/products/ultracompact/uc1394a-3.html Just add an ADC for a high-performance SDR! Leon -- Leon Heller, G1HSM leon.heller@bulldoghome.com http://www.geocities.com/leon_heller ---[This E-mail has been scanned for viruses but it is your responsibility to maintain up to date anti virus software on the device that you arecurrently using to read this email. ] _______________________________________________ Xylo-SDR mailing list To post msg: Xylo-SDR@ae5k.us Subscription help: http://lists.ae5k.us/listinfo.cgi/xylo-sdr-ae5k.us Xylo-SDR web page: http://xylo-sdr.ae5k.us Forum pages: http://www.hamsdr.com/hamsdrforum/
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