Challenge Description

Some amateur radio hackers captured a strange signal from space. A first analysis indicates similarities with signals transmitted by the ISS. Can you decode the signal and get the information?

Provided Files

We are only provided with a wave file: Signal.wav.

Solution

During early space exploration, pictures where transmitted using a transmission method called Slow-Scan Television (SSTV). Amateur radio operators and the ISS still use this method to transmit and receive pictures via radio in monochrome or color.

To solve this challenge we can use qsstv, a FOSS program that can decode SSTV transmissions to pictures.

Once we open qsstv, we need to go to Options > Configuration and under the Sound tab make sure that the option Sound Input is set to From file.

We then click the Receive (play) button, load Signal.wav and wait for the image to be generated revealing the flag: