Transmitting and Receiving Text Data via an MP3, FM Transmitter and RTL-SDR

Over on his YouTube channel Kris Occhipinti has uploaded some videos where he shows how he is able to send text data over FM radio frequencies by using an MP3 audio file that  encodes the text data, an FM transmitter connected to an Android phone or MP3 player to transmit the file and an RTL-SDR on the receiving side to receive the FM signal from the FM transmitter. The software used to encode the text into an MP3 is Minimodem, and on the receiving side Minimodem is also used which can easily decode the received audio. Minimodem is a command line program which can generate FSK modem tones from data.

These two videos are part of a series that Kris has been working on that includes many videos about using Minimodem to transfer data like text, files and images between computers via radio.

12 Minimodem an FM Transmitter and a USB SDR Dongle

13 Radio Data Trasmission with RTL FM and SDR

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Someone is having a lot of great time! Nice work, thx!


Great job Giamma! very interesting but not for everyone ..

below some of my personal tests performed with the FM transmitter and SSTV transmission decoding with Robot36 and Android phone:

below some of my personal tests performed with the AM transmitter and PSKR500 and MFSK128 transmission decoding with Tivar and Android phone:

below a guide to self-build the transmitter:

some apps to play with rtl-sdr and at the end of the page some proof of concept:

other tests:


The worst presentations we have ever seen.


right?! It’s like, what did we even pay for?! All this individual did was experiment and contribute data…. it wasn’t even made beautiful and professional… rip off!!!

Bendail Vam

I think it was spectacular – hopefully hes a ham and can play with all sort of xmitting and stuffs.


You may also want to test SSTV with the same transmitter.