Field Guide · term

Also known as: control channel

The control channel is the data-only frequency that coordinates a trunked radio system.1 It carries a continuous stream of signalling — never voice — managing registrations, call requests, and channel grants.

control channel — continuous data, never voice grant→ ch 3 affiliationradio 4567 grant→ ch 7 decode this first — it's the map to every call
The control channel carries the system's running commentary — affiliations, requests, and channel grants.

How it works

When a call starts, the control channel broadcasts a grant naming the talkgroup and the assigned voice channel; affiliated radios retune to listen. It also conveys the system identity and parameters.

Relevance to SDR

Decoding the control channel is the key to monitoring a trunked system — it is the map that tells GopherTrunk where every call goes, so it can follow them all.

Sources

  1. Trunked radio system — Wikipedia, on the control channel and trunking signalling. ↩

See also

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