Application note on using rpitx

Using with csdr to modulate streaming input

You will need the dev branch of csdr for doing this.
Setup instructions:

git clone https://github.com/simonyiszk/csdr.git
cd csdr
git fetch
git checkout dev
make && sudo make install 

Note that it should be already done, if you installed qtcsdr.

Modulate from raw audio file

Generate AM modulation:

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

• It will read the raw audio file testsound48000.raw, which is present in this repo. You can get this file by:

  git clone https://github.com/ha7ilm/rpitx-app-note cd rpitx-app-note; ls #There is your file.

• The part csdr gain_ff 1.0 can be changed to increase/decrease modulation.

• The -f 28400 at the end gives the transmit frequency in kHz.