Wow - it's almost like you read my mind.
I was putting this low cost (high value) solution together which interfaces to the Rasberry Pi (we're calling it the RD3). It is basically an FPGA with a high speed DAC and a high speed ADC. At first we're putting some simple applications on this platform : oscilloscope, signal generator, logic analyzer, but we were planning on a Software Defined Radio application later.
The ADC and DAC will be 8 bits of resolution at 100 MHz (after some feedback from this forum, I discovered there is interest in a 10 bit ADC at 65 MHz for a higher price, so we're planning to do an "A" version to support this). The FPGA itself is a Cyclone 3C5 (5100 Logic Cells, 23 multipliers (18x18), 46K bytes of memory). We picked a package which allows us to upgrade to the 3C25 (25K logic cells, 66 memories, 66 multipliers) if there's a demand for it.
Connect it up to a radio module, and you can do your own SDR.
The FPGA gets it's configuration file from the Raspberry Pi, and we're planning on communication via SPI interface.
Here's two links to what we were planning :
http://www.wattminderinstruments.com/view/15
http://www.wattminderinstruments.com/view/16
Right now, we've sent out for some PCB's to be fabricated, and we'd love to hear any feedback.
(I'm seeing if I can get our web master to do a registration link so we can let interested parties know about our progress. I'll post a link once we get it going).
Best Regards,
Tony
