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