Sniffing & Spoofingradiodecoderpocsagdtmfzveirtl-sdrdigitalvhfuhf

multimon-ng

multimon-ng is a digital radio transmission decoder that supports multiple modes commonly found on VHF/UHF bands. It is the successor to multimon with improved compatibility for modern systems.

Description

multimon-ng decodes various digital transmission modes including POCSAG512, POCSAG1200, POCSAG2400, FLEX, EAS, UFSK1200, CLIPFSK, AFSK1200, AFSK2400 variants, HAPN4800, FSK9600, DTMF, ZVEI1-3, DZVEI, PZVEI, EEA, EIA, CCIR, MORSE CW, and X10. Multiple decoders can run concurrently on the same signal provided via a file, pipe, sound card, GNU Radio sink, or UDP audio stream from tools like gqrx.

Common use cases involve processing raw input from RTL-SDR devices via rtl_fm, or audio from sound hardware. It is particularly useful for monitoring pager traffic (POCSAG), tone signaling (DTMF, ZVEI), and other VHF/UHF digital protocols. Setups often require piping samples from radio receivers, potentially with sound card modifications.

The tool reads from default sound hardware if no file is specified, or from stdin via '-', and supports sox for non-raw input types.

How It Works

multimon-ng processes audio or raw samples to demodulate specified digital radio protocols using concurrent demodulators. Input is read from files, stdin, or sound hardware; raw input uses -t raw, others require sox. Enabled demodulators like POCSAG512 decode pager signals in modes such as alpha (-f alpha). It lists available demodulators on startup and supports verbosity levels for output control.

Installation

bash
sudo apt install multimon-ng

Flags

-t <type>Input file type (any other type than raw requires sox)
-a <demod>Add demodulator
-s <demod>Subtract demodulator
-cRemove all demodulators (must be added with -a <demod>)
-qQuiet
-v <level>Level of verbosity (e.g. '-v 3')
-f alphaDecode in alpha mode

Examples

Take raw input from rtl_fm, add POCSAG512, POCSAG1200, POCSAG2400, and SCOPE modules, decode in alpha mode, reading from stdin
rtl_fm -f 149.614M -s 22050 -p -19 | multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400 -a SCOPE -f alpha /dev/stdin
Read input from stdin with default demodulators
multimon-ng /dev/stdin
Read input from standard input as denoted by filename '-'
multimon-ng -
Process a single input file with default demodulators
multimon-ng [file]
Process multiple input files
multimon-ng [file] [file] [file] ...
Use raw input type and add specific demodulators POCSAG512 and SCOPE
multimon-ng -t raw -a POCSAG512 -a SCOPE
Run in quiet mode
multimon-ng -q
Updated 2026-04-16kali.org ↗