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raspberry-pi2gnuradiosoftware-defined-radio

GNU Radio and bladeRF on Raspberry Pi (simple FSK system)


I am having a problem porting a GNU Radio setup from PC (windows 10, USB3) to Raspberry Pi 2 (USB2). USB bandwidth and CPU should not be a problem I think (only around 30% utilization while running). Essentially it looks like the RPi is 'pausing' during transmission, while the PC is not. The receiver is running on PC in both cases. I am including a pic of what I see after the FSK demod when running transmitter on PC vs Pi (circled 'pause' area), as well as a picture of my (admittedly sloppy) schematic. Any help/tips is greatly appreciated.gnuradio schemreceived signals

Edit: It appears it may actually be processing limitations. Switching from 9400 baud to 2400 baud makes the issue go away. If anyone has experience with GNURadio...am I doing anything overly inefficient or should I just drop comm rate?


Solution

  • The first thing I would do would be to lower your sample rates. You don't need 1.5Ms/s if you are going to keep only the lowest 32k in your low pass filter.

    Then you could do the same for your second stage after the quadrature demod if it's not enough (by the way, the sample rate of your second low pass filter does not seem to match the actual sample rate of the stage which is still 1.5Ms/s if I'm not mistaken).

    Anyway, Gnuradio uses a lot of processing power so try not to use a sampling rate way above what you actually need ;)

    In your case, you could cut the incoming sample rate down to 64k (say 80 for safety). 18 times less samples to process might do the trick :)