man rtfm — Sounds of Earth
root@goldstone-relay:~# man rtfm
RTFM(1)SURVIVOR FIELD MANUALRTFM(1)
RTFM
// you read it. miracle. half of you are still holding the antenna wrong.

Synopsis

rtfm [--listen] [--look] [--decode] [--keep-every-scrap] [--do-not-transmit]

Description

Something answered the Golden Record and poisoned the bands on the way in. This is a chain: you pull a signal out of the noise, decode it, and each thing you decode is the key to the next door. It's radio, audio, but use all of your senses. No shells to pop, no ports to scan — if you're running nmap you're in the wrong con room.

The Five Commandments

  1. Chase those waterfalls. You perceive with your mind, not just your eyes and ears. If it sounds like garbage, that's a feature — open a spectrogram.
  2. Look at the sound. Pictures hide in it more than one way. What worked last time may not work this time — notice which.
  3. Keep every scrap you decode. A word you pull off one signal is the key to another. Write it down. You will not remember it. You never do.
  4. Auto is your friend. Half these modes self-sync. Stop hand-tuning things the decoder already knows.
  5. RECEIVE. DO NOT TRANSMIT. Nobody here needs you keying up. See EXIT STATUS.

“Required” Kit (only if you're going it alone)

None of this is actually required. Want to be a lone wolf? Then yes, you'll want these. But we're in this together — there are radio engineers and a staffed station on site to help you pull these signals down. Ask. That's what they're there for.

RTL-SDR + rtl_433your ears in the sub-GHz mud. learn rtl_433 -c <conf>. a config file does the tuning; you do the reading.
spectrogram appSpectroid / SpectrumView on a phone, or Audacity → Spectrogram on a laptop. this is the whole game, honestly.
CyberChefbookmark it. you'll want From Hex, From Base64, and XOR. that's not a hint, that's a life skill.
an SSTV decoderRobot36 / Black Cat SSTV / QSSTV. set it to Auto and let it draw. not everything screechy is a spectrogram.
Morse, ishlearn it, or point a decoder at it. ·− ·−·· etc. older than the static, still runs.
a notebookanalog. for the scraps. yes, really.

Signals Found (a running log — add to it, share it)

Start on FM — most of what's left is bleeding through there, mostly garbled. But sit on 90.5 and 102.7 a while and readable pieces surface out of the hiss: half a word, a bar of music, a voice that stops when you lean in. They come through like they're broadcasting from another time — or somewhere the dial was never meant to reach. Log what you catch.

433.920 MHz  ·  OOK  ·  sample-rate 250k
sub-GHz still breathes when nothing else does. point rtl_433 at it:
rtl_433 -f 433.92M -s 250k -X 'n=voyager,m=OOK_MC_ZEROBIT,s=250,l=0,r=2000,preamble=2dd42d'

FM broadcast band  ·  WFM  ·  "where the music was"
every station carries the same cold voice now. the voice isn't the message — look at it, don't listen. something older than radio is tapping underneath.

FM broadcast band  ·  WFM  ·  the screech after the voice
not noise. the Record drew its pictures instead of playing them, and so does this. open a spectrogram and read what it draws.

144.390 MHz  ·  AFSK / APRS 1200 baud
packets, stamped with a date you'll recognize. the relay shack decodes them onto the board — read them there. then From Hex → XOR with the words the Record taught you.

— the reply —  ·  SSTV
the last picture, slow-scanned back at us. set an SSTV decoder to Auto, play it from the start, and let it draw.

Common Ways To Waste An Hour

  • Listening to a signal that wants to be seen. If your speaker only coughs static, you're using the wrong sense.
  • Trying to brute-force a flag{}. It's in there. Decode, don't guess.
  • Ignoring the words you already decoded. The manual said keep the scraps. You didn't. Go back.
  • Standing at the relay shack asking it to decode faster. It reads the packets onto the board. Read the board.

Modes(7) — Quick Reference

OOK / ASKon-off keying. little beacons. rtl_433 territory.
WFMbroadcast FM. where the "music" used to be.
CWmorse. dits and dahs.
AFSK / APRSaudio packets. the shack decodes them for you.
SSTVslow-scan pictures. auto-detects its own mode.
spectrogramnot a mode — a way of looking. your best friend.

Rules Of Engagement

  • Attack the puzzles, not the infrastructure. No DoSing the scoreboard, the relay, or the org running on three hours of sleep.
  • Share knowledge and hints — that's the whole point. Just don't be the person who shares flags.
  • Hints exist for when you're truly stuck. They cost you. Pride costs more.
  • Do not transmit. Especially not on the band marked "THE ANSWER." We mean it.

Exit Status

0  you found the flag. touch grass.
1  you tried to listen to a picture. re-read Commandment II.
2  you threw away a scrap you'll need in two stages. re-read Commandment III.
137 you transmitted on 1420.405 MHz. something knows your name now. good luck.

See Also

the-band-plan(1), waterfall(7), patience(3), your-own-notes(5).  — now go. the dark is waiting for an answer.