2015-11-08 13:38:47 +00:00
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# Application note on using rpitx
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## Using with csdr to modulate streaming input
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You will need the *dev* branch of *csdr* for doing this.<br />
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Setup instructions:
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git clone https://github.com/simonyiszk/csdr.git
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cd csdr
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git fetch
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git checkout dev
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make && sudo make install
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Note that it should be already done, if you installed *qtcsdr*.
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### Modulate from raw audio file
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2015-11-08 13:41:57 +00:00
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These examples will use the raw audio file `testsound48000.raw`, which is present in this repo. You can get this file by:
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2015-11-08 13:38:47 +00:00
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2015-11-08 13:41:57 +00:00
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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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2015-11-08 13:38:47 +00:00
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2015-11-08 13:41:57 +00:00
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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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2015-11-08 13:38:47 +00:00
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2015-11-08 13:41:57 +00:00
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**Generate AM modulation:**
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cat testsound48000.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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2015-11-08 13:38:47 +00:00
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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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