Field Guide · protocol

Also known as: MDC-1200, MDC1200

MDC-1200 (Motorola Data Communications) is an in-band signalling system that sends a short 1200 bps FFSK data burst over an otherwise analog FM voice channel. It conveys a transmitting radio’s unit ID (PTT ID / ANI), plus emergency and status signalling.1

MDC burst analog FM voice unit ID 1200 bps FFSK at start (and optionally end) of PTT
MDC-1200 sends a brief FFSK data burst (the unit ID) at the start of an otherwise analog transmission.

Overview

When a user keys up, the radio can send a brief MDC burst at the start (and/or end) of the transmission identifying the unit — giving an analog system some of the radio-ID visibility that digital systems carry natively. Emergency and status features ride on the same signalling.

Technical characteristics

Property Value
Modulation 1200 bps FFSK
Carries Unit ID, emergency, status
Channel Over analog FM voice
Error control Parity / repetition

History

Developed by Motorola for conventional and trunked analog systems as a lightweight data-signalling layer; widely used by public-safety and business fleets.1

Deployment

Analog FM systems needing unit identification and emergency signalling, including many public-safety conventional channels.

Decoding it with GopherTrunk

GopherTrunk detects the FFSK burst on analog channels and decodes the unit ID and flags. See the MDC1200 decoder page.

Sources

  1. MDC-1200 — Wikipedia, for Motorola’s in-band FFSK signalling system, its PTT-ID/ANI, and emergency/status features. ↩ ↩2

See also

Learn it step by step

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