kopia lustrzana https://github.com/ha7ilm/rpitx-app-note
Update README.md
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README.md
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README.md
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@ -20,22 +20,22 @@ These examples will use the raw audio file `music48000.raw` and `speech48000.raw
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git clone https://github.com/ha7ilm/rpitx-app-note
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cd rpitx-app-note; ls #There is your file.
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A raw audio file differs from a .wav file because it doesn't have any headers to store its parameters, just the samples after each other.
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We will play these files in a loop, you can stop it with Ctrl+C.
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**Generate AM modulation:**
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cat music48000.raw | csdr convert_i16_f | csdr gain_ff 1.0 | csdr dsb_fc | csdr add_dcoffset_cc | sudo rpitx -i- -m IQFLOAT -f 28400
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(while true; do cat music48000.raw; done) | csdr convert_i16_f | csdr gain_ff 1.0 | csdr dsb_fc | csdr add_dcoffset_cc | sudo rpitx -i- -m IQFLOAT -f 28400
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* The part `csdr gain_ff 1.0` can be changed to increase/decrease modulation.
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* The `-f 28400` at the end gives the transmit frequency in kHz.
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**Generate USB modulation:**
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cat speech48000.raw | csdr convert_i16_f | csdr dsb_fc | csdr bandpass_fir_fft_cc 0 0.1 0.01 | csdr gain_ff 2.0 | csdr shift_addition_cc 0.2 | sudo rpitx -i- -m IQFLOAT -f 28400
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(while true; do cat speech48000.raw; done) | csdr convert_i16_f | csdr dsb_fc | csdr bandpass_fir_fft_cc 0 0.1 0.01 | csdr gain_ff 2.0 | csdr shift_addition_cc 0.2 | sudo rpitx -i- -m IQFLOAT -f 28400
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**Generate LSB modulation:**
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cat speech48000.raw | csdr convert_i16_f | csdr dsb_fc | csdr bandpass_fir_fft_cc -0.1 0 0.01 | csdr gain_ff 2.0 | csdr shift_addition_cc 0.2 | sudo rpitx -i- -m IQFLOAT -f 28400
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(while true; do cat speech48000.raw; done) | csdr convert_i16_f | csdr dsb_fc | csdr bandpass_fir_fft_cc -0.1 0 0.01 | csdr gain_ff 2.0 | csdr shift_addition_cc 0.2 | sudo rpitx -i- -m IQFLOAT -f 28400
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* It's the matter of the filter which sideband do we select:
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* `csdr bandpass_fir_fft_cc -0.1 0` is the lower sideband
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@ -44,5 +44,10 @@ A raw audio file differs from a .wav file because it doesn't have any headers to
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**Generate NFM modulation:**
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cat music48000.raw | csdr convert_i16_f | csdr gain_ff 7000 | csdr convert_f_samplerf 20833 | sudo rpitx -i- -m RF -f 28400
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(while true; do cat music48000.raw; done) | csdr convert_i16_f | csdr gain_ff 7000 | csdr convert_f_samplerf 20833 | sudo rpitx -i- -m RF -f 28400
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**Generate WFM modulation:**
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(while true; do cat music48000.raw; done) | csdr convert_i16_f | csdr gain_ff 70000 | csdr convert_f_samplerf 20833 | sudo rpitx -i- -m RF -f 28400
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* Frequency deviation is set much higher with `csdr gain_ff 70000`, that's the only difference between this and NFM.
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