##  void
```bash$ file output.wavoutput.wav: RIFF (little-endian) data, WAVE audio, mono 48000 Hz```
Google `wav "mono 48000 Hz" "ctf"` and we find http://g4ngli0s.logdown.com/posts/1422073-bsidessfctf-for-latlong. The spectrum analysis on that page looks exactly like the one we see in Audacity. Copy the commands they used, adapted to the file names used in this challenge.
```bash$ sox -t wav output.wav -esigned-integer -b16 -r 22050 -t raw output.raw$ ./multimon-ng -t raw -a AFSK1200 output.raw```Or do everything in one command:```bash$ cat output.wav |    sox -t raw -esigned-integer -b 16 -r 48000 - -esigned-integer -b 16 -r 22050 -t raw - |    multimon-ng -t raw -a AFSK1200 -f alpha -
multimon-ng 1.1.8  (C) 1996/1997 by Tom Sailer HB9JNX/AE4WA  (C) 2012-2019 by Elias OenalAvailable demodulators: POCSAG512 POCSAG1200 POCSAG2400 FLEX EAS UFSK1200 CLIPFSK FMSFSK AFSK1200 AFSK2400 AFSK2400_2 AFSK2400_3 HAPN4800 FSK9600 DTMF ZVEI1 ZVEI2 ZVEI3 DZVEI PZVEI EEA EIA CCIR MORSE_CW DUMPCSV X10 SCOPEEnabled demodulators: AFSK1200AFSK1200: fm WDPX01-0 to APRS-0 UI  pid=F0!/;E'q/Sz'O   /A=000000zh3r0{ax25_is_c00l__dm_me_the_solution}```
yielding the flag `zh3r0{ax25_is_c00l__dm_me_the_solution}`