So here I am just browsing through the electro-magnetic spectrum with gqrx and I come across a signal…a strong signal at that. Obviously this piqued my curiosity so I decided to check it out. I started out by recording just the raw signal with GNURadio and saving it to a file. Afterwards I ran it through a few filters and put it up on the scope sink, and FFT. In the end (with the help of a constellation plot) I was able to figure out it was FSK modulated. I quickly demodulated the signal and through the contents into another file to check out with a hex editor.
I have no clue what this is, but I do have a pretty good guess. I did some research and found that these could be the possible culprits:
American H Block Wireless L.L.C. (aka Dish Network) Call-sign – WQTX279 Use – H-Block Broadband (voice or data)
Powertel Memphis Licenses, Inc. (aka Bloomberg) Call-sign – KNLF619 Use – Personal Communication Services
Cellular South Licenses, LLC (aka ATT) Call-sign – WQPX714 Use – Personal Communication Services
Now, my best guess is that it would either be Cellular South, or Powertel. I say this because here within the past few months some company just recently installed a new tower about 0.5 miles down the road from my house, and Dish still doesn’t have any infrastructure in place for any wireless networks (even though they own a HUGE chunk of the spectrum). Odds are it’s Cullular South, but who knows.
Anyways, on to some pictures.
Looking a histogram and constellation of the signal.
Looking at the raw bits from the signal. (9/10 they are encrypted so I stopped here)