MULTIMON(1)

📦 version 1.0, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 MULTIMON(1) — the group chat guide to multimon 💖

okay bestie, sit down, we're decoding radio transmissions today ✨

This is the manual page for multimon, from the General Commands Manual section (that's section 1, iykyk). It's a whole program for decoding radio transmissions and honestly? She's iconic. 👑

🌸 NAME 🌸

multimon — the program that decodes radio transmissions 💅

✨ SYNOPSIS ✨

multimon [options] [input_file]

🦋 DESCRIPTION 🦋

Okay so, real talk: this manual page is a brief little overview of the multimon command. It got written for the Debian GNU/Linux distribution because the original program literally does not have a manual page — so we made one, you're welcome. 🫶

The multimon software can decode a variety of digital transmission modes commonly found on UHF radio. A standard PC soundcard is used to acquire the signal from a transceiver, and the decoding is done completely in software. No cap. 🎀

Currently, these are the modes she supports:

  • AX.25
    • 1200 Baud AFSK
    • 2400 Baud AFSK (2 variants)
    • 4800 Baud HAPN
    • 9600 Baud FSK (G3RUH)
  • POCSAG
    • 512 Baud
    • 1200 Baud
    • 2400 Baud
  • Miscellaneous
    • DTMF
    • ZVEI
    • SCOPE

An arbitrary set of the modes above may run concurrently on the same input signal (as long as the CPU power is sufficient, so… vibe check your machine first 💀). Which means you do not have to know in advance which mode is being used. Slay.

But bestie, heads up: some modes might require modifications to the radio to work properly — especially the 9600 baud FSK and the POCSAG modes. Not me warning you twice. 😭

Let's break the acronyms down, because we're not gatekeeping:

  • AX.25 — Amateur Packet Radio protocol datagram format
  • POCSAG (Post Office Code Standards Advisory Group) is a common paging transmission format.
  • DTMF — Dual Tone Multi Frequency. Commonly used in in-band telephone dialing.
  • ZVEI — The German Electrical and Electronic Manufacturers' Association — paging tone format.
  • SCOPE — show samples in a rudimentary oscilloscope display on an X server.

And one thing she does NOT do: Multimon does not decode Morse code signals. Periodt. 🚫

💅 OPTIONS 💅

  • -t <type> — input file type (any other type than raw requires sox). allowed types: raw aiff au hcom sf voc cdr dat smp wav maud vwe
  • -a <demod> — add demodulator
  • -s <demod> — subtract demodulator
  • -v <num> — verbosity level (0-10)
  • -q — quiet output messages

Where <demod> is one of: POCSAG512 POCSAG1200 POCSAG2400 EAS AFSK1200 AFSK2400 AFSK2400_2 HAPN4800 FSK9600 DTMF ZVEI SCOPE

The -a and -s options may be given multiple times to specify the desired list of demodulators. Stack 'em up, bestie. 🔥

🌈 EXAMPLE 🌈

Decode signal modulations from a sound file /tmp/message.wav without using a SCOPE display:

multimon -s SCOPE -t wav /tmp/message.wav

With no input file specified, the program listens directly to the sound card using the /dev/dsp interface. So to decode (only) DTMF tones on the sound card input:

multimon -a DTMF

🎀 NOTICE 🎀

Please note that monitoring commercial services may be prohibited in some countries, so this software should therefore only be used to monitor the amateur radio service. Stay legal, bestie, fr fr. 🙈

⭐ SEE ALSO ⭐

💀 BUGS 💀

The DTMF and ZVEI decoders have more frequent spurious detection reports. So if they start saying wild stuff, that's just their main character energy, not a real signal. 😭

🫶 AUTHOR 🫶

This manual page was written by A. Maitland Bottoms <bottoms@debian.org>, for the Debian GNU/Linux system (but may be used by others). Giving credit where credit is due, always. 💖

and that's the whole page, bestie ✨

This little beauty is from MULTIMON(1), dated June 19, 2000 — yeah, she's vintage and she still ate. Go decode something iconic. 👑💅🌸

📦 where this page comes from