Re: [Discuss-gnuradio] Low-cost hardware options

[Marcus D. Leech]

On 01/15/2011 08:53 AM, Marcus D. Leech wrote:
>
> Yes, I considered that, too, and it would be cheap to do.  I'll update the
>   block diagram.
>
>   
Updated the diagram to include external (non-mixed) input capability,
right before the
  anti-alias filters, using a Hitite RF switch.

Also upgraded to the next speed-grade of the ADC, to give 40Msps, and
changed the spec
  on the anti-alias filters to suit.

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

With PCB, the BOM costs shouldn't be more than about $125.00 for this
board.  With
  a larger physical board, you might be able to route this on only two
layers, making
  the PCB relatively cheap.

So, let me propose that we put some stakes in the ground, to focus the
discussion a little:

    o Assume a "dumb" ADC
       o The AD9238 is still in production, available through Digikey,
and available in the 40Msps version
          for $18.65.

    o Assume that some kind of FPGA will interface to the outside world,
and provide
       first-level DSP services (DDC, CIC Decimator and FIR filtering, etc).

    o Assume a generic interface to an FPGA host-transport platform
        o I've shown an FMC connector, which is fine for boards like the
SP601
        o The Nexsys2 from Digilent uses a different connector
        o Choose one and have a super-cheap adapter card?
        o Have both connectors on the board, and "be clever"?
           [Could become a routing nightmare]

I'll observe that the Nexsys2 provides academic discounts of about
$50.00 on the Nexsys2, which
  could be a real boost to the starving-student crowd.

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