Hi Marcus, I'm not getting overruns, and the signal source was the N210 (I was doing a loopback test). I switched to a hardware radio to transmit data, and the spikes went away. Is that what you'd expect? The spikes were 2000-3000 samples apart. If you don't think I should see those spikes even when the SDR is receiving from itself, I can investigate trying different frequency settings.
What equation can be used to calculate supported sample rates? Is it just clock (default 50 MHz, but I think it can be set to other values) divided by any integer value, only even integers, etc...? I just used the sample rate someone had chosen before I inherited the code, and it didn't generate any warnings about not being a value supported by the hardware (which is what I saw when switching the frequency to other values). Thanks, Sean On Fri, Jul 14, 2017 at 1:52 PM, Marcus D. Leech <mle...@ripnet.com> wrote: > On 07/06/2017 12:46 PM, Sean Horton wrote: > >> Hi, >> >> I've recently gotten someone with Matlab to help me look at what's going >> on in my receiver. The image was created with matlab from data from a file >> sink connected directly to a usrp source. I am seeing spurious spikes when >> plotting I or Q, and I'm not sure where they could be coming from, or how >> to get rid of them. I know what I think I'm about to transmit doesn't have >> those spikes. >> >> Some info that might be helpful: >> Using a N210 with a UBX connected directly to my desktop. >> I have tried a few sample rates (96000, 201613). >> I am currently doing a loopback test, though working on getting the sdr >> to listen to a signal generated by another piece of equipment. >> This doesn't stop me from being able to decode what is transmitted, but >> since my issue is I can't decode messages with as low of an SNR as I >> expect, I'm trying to examine everything as closely as possible. I'm off by >> 20-30 dB. >> The entire path to get to matlab is: usrp_source -> file_sink -> Python's >> scipy in order to read in the raw data and store it in a .mat. >> >> Also, if any responder would be kind enough to also point out how I >> properly respond, that'd be great. I know I can't just hit reply to the >> digest, and I also can't change the subject line when I hit reply in the >> digest, so I'm sort of stumped. I have had digest mode on, so I'll turn >> that off for now. >> >> Thanks, >> Sean >> >> -- >> Sean Horton >> >> >> Sean: > > So, I'll note that for an N210, neither of those sample rates are > supported precisely by the hardware. > > Are you getting overruns when recording the data? > > What is the source of the signal? > > What frequency, and do the spikes come/go with frequency setting? > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -- Sean Horton
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