[Background - the Janus board is a high performance A/D and D/A converter
that connects to the PC via USB. It will provide full duplex operation at
up to 192k samples per second at 24 bits. The hardware is based on an FX2
USB interface feeding an FPGA and high performance A/D and D/A converters.
The FPGA will also be used in conjunction with a GPS 1pps clock, or
stabilized oscillator, to enable any frequency error and drift of the
200MHz
DDS clock to be corrected within the PowerSDR software. The hardware and
software for the project is being developed by Bill KD5TFD and Phil VK6APH
and will be open source.]
We have now successfully tested the TLV320AIC23B as a microphone amplifier
and Audio out/Headphone amplifier for the Janus USB high speed A/D and
D/A board.
We need to decide what connectors we want on the edge of the board and how
many.
The latest block diagram is here:
< http://www.hamsdr.com/dnld.aspx?id=139 >
Since the board is 100mm (~4") wide then we are a little tight for space.
I suggest 3.5mm jack sockets for the microphone and headphones. A bias
voltage is available for Electret microphones.
I also suggest using 3.5mm stereo jacks for the high speed A/D inputs.
Since all the A/Ds we are considering can take a balanced input a stereo
plug will provide a balanced input and a mono plug will earth one input
for use with unbalanced inputs. This does mean that we will need two leads
from the radio as apposed to the single stereo jack at present.
We can either use 3.5mm jacks for the remainder of the sockets or consider
RCA's.
Is it worth going to gold plated RCA sockets - what experience do the
audiophiles have with these?