Oops, I sent the incorrect flight_recorder.grc flow graph without the integration block. Here's the one I referred in the email.
Thanks, -- Terrance On Fri, Sep 8, 2017 at 12:04 PM, Terrance Pat <t...@email.arizona.edu> wrote: > Hi everyone, > > I am working on a project that requires the use of the USRP B210 > and GNU Radio to act as a receiver and record signals being > transmitted from a RF source. > > Initially, I thought it would be as simple as just taking the UHD_USRP > source and piping it to the file sink. However, it becomes apparent > the file holding the raw data quickly becomes very large; on the order > of gigabytes in a matter of minutes. It is expected that the receiver > will be collecting data for several hours and our disk space in the > receiver system is rather limited. > > One person suggested having the software > accumulate or integrate the data samples after they've been FFTed for > a predetermined duration of integration time before writing to disk to > reduce the amount of overhead. > > In the attached flight_recorder.grc file, I insert an integration > block between the USRP source and the file sink to do this, but using > the flight_recorder_playback.grc to play back the signal shows that > the sample rate is significantly reduced. Initially I thought > decimation had something to do with the time duration the integration > is done with the samples, but that was not the case and further > research showed decimation is defined as reducing the sampling rate. > > I also tried the same approach in the attached flight_record_fft.grc > flow graph with the difference being I pipe the raw data to the FFT > block before running it through the integration block and writing to > disk. > > Accumulating the data for some integration time should increase my > signal to noise ratio, but that is not happening with my current > approaches and there doesn't seem to be a way to tell the integration > block to integrate over a constant time duration. Perhaps I > misunderstood how the integration block works in GNU Radio. > > Is there another approach using standard blocks in GNU Radio for > accumulating the FFTed data samples from a USRP source over a constant > integration time before writing to disk? > > I am a novice when it comes to GNU Radio and any assistance is much > appreciated. > > Thanks, > -- > Terrance
flight_recorder.grc
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