Re: [Discuss-gnuradio] USRP2 and Data Rate

[Matt Ettus]

On 07/07/2010 09:05 AM, Garrett Wenger wrote:
> Marcus,
> First of all, thanks for responding so quickly.
>
> I looked on the USRP2 faq and I did see that the DAC rate was listed as
> 400 MS/s, but later on in the faq it says:
>      The FPGA talks to the DAC at 100 MS/s just like it talks to the ADC
> at 100 MS/s. The interpolation from 100 MS/s to 400 MS/s happens inside
> the DAC chip itself. Unless you are doing something fancy, you can think
> of the
>      DAC as operating at 100 MS/s.
>
> If I am just misunderstanding that and I do need to use 400 MS/s as my
> DAC rate, is there some upper limit to what the samples per symbol value
> can be? Since interpolation has to be between 4 and 512, the lowest
> possible values that I could use to get a 10kbps would be 80 samples per
> symbol with 500 as my interpolation rate.


Do all sample rate calculations based on a 100 MS/s DAC, just like the 
ADC.  So an interp rate on transmit of X will have the same sample rate 
as using decim rate X on receive.

Matt