Hi Brian, Thank you for your help. Looks good :) So If I understood correctly I can do the following:
I set the USRP interpolator to 64, so the USRP sink will consume samples at a 2MS/s. I add the resampler just before with a ratio 16/13 so I it consumes samples with a 1.625MS/s rate. Just before that I have the GMSK filter with a interpolation factor of 6 so at the input it is consuming samples at the desired rate 270833.333 Samples/s. At hat point can I send the samples (for example from a file with gr.file_source) and guarantee they will be treated as a 270.8333Ks/s stream? (assuming there will be enough samples to process) Thank you again for your help! On Mon, Apr 14, 2008 at 8:55 PM, Brian Padalino <[EMAIL PROTECTED]> wrote: > On Mon, Apr 14, 2008 at 8:03 PM, Wireless Monster > <[EMAIL PROTECTED]> wrote: > > Hi All, > > > > I am new to gnuradio and the USRP board and I have a basic question. > > > > I want to transmit a GSM signal. Once It is encoded I have a 270833.333 > > symbols/sec signal. Then, it is up-converted (x8) and GMSK filtered, so > I > > get a 2.1666 Ms/s complex signal. > > > > Now the question: How to adapt this rate to the DAC converter on the > USRP > > board? > > Well, if you don't use your x8 upconversion, you can get away with a > rational resampling (I believe). > > Taking 270833.333, and upconverting by 3x makes the sample rate > 812500. If you then rationally resample this by 16/13, you get a nice > 1Msps signal which you can upconvert by a nice power of 2 for the > USRP. > > Try it out and let us know how it works out? > > Brian >
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