Re: [Discuss-gnuradio] Re: "Open-Hardware"

[Marcus D. Leech]

> schrieb Marcus D. Leech am 2011-01-12 02:40:
> There is a lot of people outside the Linux world, especially in the
> non-academic hobbyist corner. These people seem to me to try to work
> with least possible changes, that is install no new OS, install no
> additional tricky exotic drivers, and at most plug in some USB device.
> That's perfectly ok for me. If these people should be serverd as well
> you unfortunately _have_ to to think about Windows, as hard and painful
> as it may seem.
Yup, I reluctantly agree.  But I have to assume that UAC2 is the "future" of
  USB Audio devices, and as such, should probably be the way to go forward.
  I'm pretty sure that the USB consortium didn't invent UAC2 purely for
  LInux users :-)

Now, to keep ideas ball rolling here:


So, by way of a start on a cheap(ish) receive chain block-diagram, I 
whipped-up this:

http://www.sbrac.org/files/digital_receiver2.pdf

This has a "reasonable" RF Rx chain, and includes a "reasonable" 
(20Msps) ADC.
  The "trick" is that instead of doing decimation in an FPGA, you 
select the correct
  filter from the bank, and change the ADC clock rate.  Discrete 
passive filters are
  reasonably easy to design and fabricate, and if there are only, let's 
say, four of
  them, covering 4 different desired SPS rates, that might be acceptable.

Also, the design "terminates" in an FMC connector, which allows you to 
mate this up with
  something like a Xilinx FPGA+1GiGe card, like the SP601 or similar.

If one desired USB instead, then a simple EZ-FX2 USB-2.0 card with an 
FMC connector on it, and whatever
  logic was necessary to grab samples from the ADC could be designed 
and built.

A "wrinkle" in such a design is that one is at the mercy of the tuning 
resolution of the down-converter,
  since there's potentially no DDC (unless you implemented one on the 
FPGA card).

--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org