Re: [Discuss-gnuradio] FPGA Questions

[Eric Blossom]

On Sat, Feb 24, 2007 at 05:13:22PM -0500, Brian Padalino wrote:
> On 2/24/07, Thibaud Hottelier <address@hidden> wrote:
> >Hi all,
> >
> >I have dived into the fpga code and I have now much clearer picture of
> >what is going on, but also much more questions :)
> >
> >The Tx CORDIC is disabled in the code I checked out. Why?
> 
> I could be wrong, but I think the TX CORDIC is disabled due to the
> fact that the samples being delivered over USB are already complex.
> Any other frequency translation is done within the AD9862 transmit
> path.
> 
> Anyone can feel free to correct me if I am wrong.

You are correct ;)


> >I have failed to find a description of how to control the AD9862 chip on
> >the Analog Device web site. Where is this documented?
> 
> http://www.analog.com/UploadedFiles/Data_Sheets/AD9860_9862.pdf


> >I would like to be able to choose the power level and the channel used
> >to transmit every packets. To choose the channel, is it possible to
> >tweak the CIC Decimating filter to slightly alter the signal frequency
> >or is it a better idea to do it in the AD9862?

The CIC interpolator doesn't perform freq translation.

If you want to change the channel, you'll want to issue the equivalent
of a "tune" command (probably several sub-operations inband)
immediately prior to sending the samples for the packet.

Yes, I know you're waiting for me to flush out the packet format.

Eric