[margalabargala]

What $15 USB SDR can transmit? All the ones I have only receive, and to transmit I'm seeing more like $100. At $15 I would buy one immediately.

[cdchn]

I think people have managed to use the GPIO pins as a bit bang transmitter.

[sebcat]

See https://github.com/F5OEO/rpitx

[riveducha]

Sorry, my wording was unclear. The USB RTL-SDR was for receiving, and I did the capture and analysis on my desktop. The Raspberry Pi was for transmitting using the GPIO pins.