I am not quite sure what data rate I am getting. I've been using a signal analyzer to receive and demod what I'm transmitting and it can generally pick up the bit sequence that I am now sending out, but I get an error rate the fluctuates from about 5% all the way up to 70% or higher. My cpfsk mod index is set to 1 and the distance between the peaks is about 10kHz, so it really seems like my data rate is somewhere around what I want it to be, but the error rate is just way to high.
Also, I went ahead and added in the interpolating filter like you suggested, but just for future reference, what is bad about having a high samples per symbol value? -Garrett On Wed, Jul 7, 2010 at 12:41 PM, Matt Ettus <[email protected]> wrote: > On 07/07/2010 08:32 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? >> > > > Your calculations appear correct, so I'm not sure why you aren't seeing > 10kbs. What rate does it give you? > > Also, 25 samples per symbol is a lot. You would probably be better off > doing an additional software decimate/interpolate by 5 operation (using an > interpolating/decimating FIR filter) and using 5 samples per symbol. > > > Matt >
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