Qsstv

Overview

qsstv is a utility for dealing with slow scan television signals. My first experience using qsstv was part of the Defcon Darknet CTF game, where one of the challenges involved slow scan TV images and several related challenges.

sstv

First, let's talk about slow scan TV. This is a method for transmitting images, pioneered by ham radio operators, for transmitting images using narrow bandwidth (3 kHz), an order of magnitude smaller than the bandwidth required to send moving television images (6 MHz).

Slow scan television was allowed for use by radio amateurs in 1968, and was utilized as a part of the Apollo lunar missions.

A sample SSTV signal is provided on Wikipedia: https://upload.wikimedia.org/wikipedia/commons/c/ce/SSTV_sunset_audio.ogg

qsstv

The utility qsstv is an open-source slow scan television program. The program does not implement any kind of radio receiver - that's the job of a handheld radio transceiver or an SDR system. It simply takes audio input from the microphone or line in. This means you can use qsstv several ways:

• set up a microphone next to your radio transceiver and tune it in to an sstv signal
• download an MP3 of a pre-recorded sstv signal
• utilize an RTL-SDR and software to tune the SDR receiver, and use that to tune into the sstv signal

Installing

This install assumes a basic "offline" setup: piping a pre-recorded SSTV signal from audio out to audio in, and demodulating it with qsstv.

Later in the page we'll look at some other, alternative configurations using SDR.

installing qsstv on kali linux

Before you begin, you'll want to set up a tool to control your audio streams: pavucontrol.

From there you can start up qsstv

pavucontrol

if you need a way to pipe audio out to audio in, use pavucontrol

apt-get install pavucontrol

configure pavucontrol

Click input devices

Click "Monitors" from drop down menu on bottom

Should see "Monitor of built-in audio analog stereo"

Click the lock to unlock it