Signals

We are given a WAV file with a lot of tones. The challenge description says:

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?

After some research on ISS (International Space Station) signals decoders, we see that these signals are used to encode images in Slow Scan Television (SSTV).

There are some Windows applications (MMSSTV) that decode ISS-SSTV signals and print the resulting image. I found a JAR application called MultiMode Cocoa that can be run everywhere Java is installed.

Unfortunately, the images are really blurred. After a lot of attempts and guessing, I got the flag. These are some of the resulting images (the best ones):

And the flag is: HTB{5l0w-5c4n_73l3v1510n_h4m_r4d10_h4ck3r}.