/sdr101

first sdr experiments

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sdr101

first sdr experimets using the HackRF and GRC

#lesson1 - basic FM radio
create osmocom source

  • Sample Rate (sps): <samp_rate> 10M - this will define the sample rate of the sdr
  • Ch0: Frequency : <center_freq> - This is set to the middle of the fm band 97.9mhz or 97.9e6
  • Ch0: RF Gain :0 - this sets the power of the recive amp set to 0 for safety

Create WXGUI FFT sink - does fft analysis on input and graphs

  • Sample Rate : <samp_rate> 10M - this will define the sample rate of the sdr
  • Baseband freq : <center_freq> - This will be the center of the graph
  • Average : on - makes the graph easier to read

now is probably a good time to connect the blocks and execute

Create Multiply block - shift a frequency to center(multiplies 2 signals)

Create variable <channel_freq> -Value : 96.5 mhz or 96.5e6

Create Signal Source - gotta remember why this actually works

  • Frequency - <center_freq> - <channel_freq>

This is a good time to test with another fft block if you want

Create low pass filter - this is the first step in demodulating (I still dont understand this part)

  • sample rate: <samp_rate>
  • cutoff freq: 75e3 or 75khz
  • transition width: 25e3 or 25khz
  • Decimation int(samp_rate/channel_width)

Create Rational resampler ( or this part)

  • interpolation:12
  • Decimation:5

Create FM reciver block

  • Quadrature Rate: 480e3 or 48khz - standard sample rate for audio
  • Audio Decimation:10

Create audo sink - last block this just inputs to sound card -sample rate: 480e2 or 48khz