Tagged: audacity

SignalsEverywhere: Decoding Digital Data via Audacity, Mulitmon-ng and MiniModem

SignalsEverywhere is back this week and in her latest video Sarah talks about using a combination of Audacity, Minimodem and Multimon-ng to decode digital data that could be obtained from an SDR or other signal source.

Sarah was interested in the 2020 Hackasat space security challenge and specifically in completing the 56k Flex Magic challenge which consists of an emulated signal from an old 56k modem. Within the 56k modem signal is secret information required to complete the challenge.

Sarah first shows how to use Multimon-ng to decode the DTMF tone section of the signal. These are the tones heard when dialling on a landline phone. She then goes on to show how to use Audacity in spectrogram mode to take a closer look and analyze the next chunk of the signal. Then by using the information gained about the signal from the spectrogram analysis she is able to decode the data via minimodem.

Audacity Decoding Data?! Using Audacity Multimon-ng and Minimodem to Decode Digital Audio Data!

Video Tutorial: Recording Audio with SDR# and Audacity

On Eric Williams YouTube channel Eric has posted a video showing how he records audio from his RTL-SDR using SDR# and Audacity. Although SDR# can record audio itself, the advantage to using Audacity is that you can set up Voice Activation (VOX), which will only record audio when someone is speaking or when a digital signal is active. This allows you to listen to a summary of communications at a later time.

RTL-SDR – Voice Activated Recording with Audacity