**Northpole Airwaves**

`During our latest expedition to the north pole, one of our scientists tuned her radio to 88Mhz and captured a slice of 1MHz (samplerate = 1M/s) to a GNURadio file sink. Surprisingly, there was more than just silence. We need your help to figure out what's going on.`

**
First analysis**
So at first glance i knew that it had to multiple parts to this since it was a 1Mhz wide recording and i wanted a easy way to visualize and examine the signals so i converted the .bin file to a .wav IQ file with the tool "sox" so that [SDR#](https://airspy.com/download/) would be able to open the file since the tool has alot of features such as fm/am demodulation and much more.

**Part 1**

Picture of SDR# [Part 1](https://imgur.com/a/QjTq1Ow)

Since SDR# has alot of features built into it i immediately noticed it had found some [RDS](https://en.wikipedia.org/wiki/Radio_Data_System) that said "Part 1/3" so i knew i was onto something here. In the waterfall plot i noticed something that looked like morse code and sure enough it was. Decoded it to `41 4f 54 57 7b 54 68 33 5f 62 65 35 74 5f 77 61 79 5f 74 30 5f` and from hex to ascii `AOTW{Th3_be5t_way_t0_`. And that looks like part 1 of the flag.

**Part 2**

Picture of SDR# [Part 2](https://imgur.com/a/xGP9mwF)

And for step 2 it was abit simpler since sdr# does all the work. The RDS decoder found a string wich   shows in the top left in the image. then i decoded   it and added to the flag. `AOTW{Th3_be5t_way_t0_spread_XMAS_ch33r:_s1` so that is part 2/3.
There was also a piece of music playing at this part of the recording wich was fm-modulated. [Link to music](https://vocaroo.com/l8HBtDf98ND)

**Part 3**

This part also hade some morse-code looking signals but always started with a long signal followed by x amount of short ones. By counting all the short signals i got the following `6 14 6 7 6 9 6 15 6 7 5 15 6 12 3 0 7 5 6 4 5 15 3 4 5 15 2 10 5 15 3 2 5 15 6 8 6 5 6 1 7 2 7 13` and if we convert what looks like decimal to hex we get the following `6e67696e675f6c3075645f345f2a5f325f686561727d` and that translates into `nging_l0ud_4_*_2_hear}`

And the complete flag is `AOTW{Th3_be5t_way_t0_spread_XMAS_ch33r:_s1nging_l0ud_4_*_2_hear}`