Demodulating and Decoding data recording with an SDR

In this series of stories I will be going over various forms of digital modulations.

Most of the posts linked were made using an RTL-SDR device with the intent to be as accessible as possible. Any SDR should work and in the future I will be using a HackRF to broadcast data encoded.


The first step in any of this is demodulation of the original data. This can be done in two ways

  1. Use your SDR software to tune to the frequency you care about
  2. Follow step 1-4 in this post from Tomasz Watorowski

AFSK – Audio Frequency Shift Keying

FSK – Frequency Shift Keying

This is the only one I’ve actually done

PSK – Phase Shift Keying

4-FSK – Frequency Shift Keying with 4 values

LoRa – Low Power Chirp Spread Spectrum

OFDM –¬†Orthogonal frequency-division multiplexing