At 1222 EST on 21 Feb 2018, we posted a new signals challenge! There are three different challenges hidden in this signal capture, and the solution to each is a text message. One is on the easier side, and the two others are more advanced. If you believe you have found a solution, DM the answer to @gnuradio on Twitter or e-mail

The first THREE people to solve each of the three challenges will be declared winners. One person can only win one challenge; if correct solutions are submitted for multiple challenges, the most valuable will count as the win (a #1 spot, for example). If someone solves all three challenges before the other nine winner spots are taken, they will be declared the Hat Trick Winner, and will receive a special one-time t-shirt. Only one of these shirts will ever be printed.

The winners will receive honor and glory. Also, there will also be stickers and t-shirts awarded! See the list below for details.

The challenge will end when all ten spots have been claimed, or at 0000 EST (GMT-5) Mon 26 Feb – whichever comes first.


Good luck, and Happy Hacking!

HINT (Posted 22 Feb): Only one of the challenges is in the obvious signal.
HINT (Posted 23 Feb): The loud broadband signal is coming from a satellite.
HINT (Posted 24 Feb): The satellite signal is imagery. The rabbit signal is normally a subcarrier with metadata.
HINT (Posted 25 Feb): Find the numbers station.

Note: The SigMF meta file has a small error – fc32_le should read cf32_le.

Challenge 1 Winners:

  1. GNU Radio t-shirt: Malcolm Stagg@malcolmst
  2. Stickers: Chris Shaw@chrishaw
  3. Stickers: Peter Pal Pusztai (Also solved #2!)

Challenge 2 Winners:

  1. GNU Radio t-shirt: Gérald Bastelica (Hat Tricked! Also solved #1 and #3!)
  2. Stickers: Daniel Brnak
  3. Stickers: James Kondel

Challenge 3 Winners:

  1. GNU Radio t-shirt: GuruMeditation
  2. Stickers: <unclaimed>
  3. Stickers: <unclaimed>

The Hat Trick:

  • Special one-time t-shirt: Sergey Prosvirov