Interfacing Spartan-3AN FPGA starter kit with BasicRX

GNU Radio
1

Hi,
I have a Xilinx Spartan-3AN FPGA starter kit and I would like to
interface it with a BasicRX.

It has a

  • 2 channel SPI-based ADC with programmable gain,
  • 4 channel SPI-based DAC

Page 75 of the user manual describes the Analog capture circuit -
AMD Adaptive Computing Documentation Portal.

The starter kit has an onboard ADC circuit with a LinearTech 14-bit
3Msps ADC. Mixed-signal and digital signal processing ICs | Analog Devices

Would this onboard ADC be sufficient to implement an FM Radio receiver
with GNU Radio? I’ve already taken a look at the USRP2 + BasicRX combo,
but I would like to know if I can somehow use the Spartan-3AN startket
kit to achieve the same results.

Best regards,

Elvis

2

On Wed, Jun 16, 2010 at 11:15 PM, Elvis D. [email protected]
wrote:

Would this onboard ADC be sufficient to implement an FM Radio receiver with GNU Radio?
Can you clarify, by “FM Radio” do you mean broadcast FM (87.5-108 MHz)?

In terms of bandwidth, 3Msps sounds sufficient, but you’ll have to
implement an FPGA design which communicates with GNU Radio. Instead of
starting from scratch, you can try to start from the USRP2 sources
(http://code.ettus.com/redmine/ettus/projects/fpga/repository/revisions/master/show/usrp2)
and apply modifications for your particular board.

To get an idea of what this is like, you can look at similar changes
we made to USRP1. There are two repos (FPGA and GNU Radio) hosted at
http://git.thinkrf.com/, look at branches ending in “wsa”. It’s a bit
of a mess at the moment, but I’d be happy to answer any questions.

Catalin
.:…thinkRF.com

3

Hi Catalin,
Thanks a lot for taking the time to reply.

On Jun 17, 2010, at 7:27 PM, Catalin P. wrote:

Can you clarify, by “FM Radio” do you mean broadcast FM (87.5-108 MHz)?

Yes, I thought I’d start with something simple, and implement a FM radio
receiver.

In terms of bandwidth, 3Msps sounds sufficient, but you’ll have to
implement an FPGA design which communicates with GNU Radio. Instead of
starting from scratch, you can try to start from the USRP2 sources
(http://code.ettus.com/redmine/ettus/projects/fpga/repository/revisions/master/show/usrp2)
and apply modifications for your particular board.

The interesting thing is that the USRP2 is based on the Spartan-3 FPGA.
On the USRP2, they’ve used an LTC2284 Dual 14-Bit, 105Msps Low Power 3V
ADC, whereas the ADC used on the Spartan 3-AN starter kit is a
LTC1407A-1 Serial 14-Bit, 3Msps Simultaneous Sampling ADC.

So, they replaced the ADC with a better one.

Where can I find the Xilinx ISE/EDK 10.1 project files that were used to
build the system for the MicroBlaze and associated IP cores?

What else would I need apart from the ADC’s? Can I directly hook the ADC
to the BasicRX and complete the RF front-end? I’m guessing that the
remaining parts would more or less be compatible, since I have the
ethernet port on the Spartan-3AN starter kit. Its just the ADC that
would be different.

Are there any other circuits that need to be put in between the ADC and
the BasicTX?

Best regards,

Elvis D.