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.
Thanks,
Garrett
On Wed, Jul 7, 2010 at 11:45 AM, Marcus D. Leech <[email protected]> wrote:
> On 07/07/2010 11:32 AM, Garrett Wenger wrote:
> > Hi all,
> > A few days ago I made a simple program using grc to fsk modulate and
> > transmit a pn sequence at 10kbps. Since I was using a USRP1, I set my
> > samples per symbol to 25 and the interpolation to 512 to get this data
> > rate.
> >
> > The place I work at just received a couple USRP2's, so I am trying to
> > get this same program working with the new devices. I realize that
> > the DAC rate for the USRP2 is 100 MS/s instead of 128 MS/s, so I
> > changed the samples per symbol and interpolation rate to 25 and 400,
> > respectively, but this does not give me the 10kbps rate like I
> > expected it would.
> >
> > Is there something major that I am missing here?
> >
> > Thanks a lot,
> > Garrett
> Garrett:
>
> The DACs on the USRP2 run at 400Msps, not 100Msps. Although the *ADCs*
> on the USRP2 do run
> at 100Msps, and that's perhaps where the confusion comes in.
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
>
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