Also known as: talkgroup, talk group
A talkgroup is a virtual channel in a trunked radio system — a numbered label identifying a group of users such as “Police Dispatch.”1 Members hear each other no matter which physical voice channel the system assigns to a given call, because the talkgroup, not the frequency, is the thing they belong to.
How it works
Every radio is programmed with a set of talkgroups it can select and monitor. When a user keys up on a talkgroup, the radio requests a call carrying that talkgroup ID; the control channel grants a voice channel and announces the talkgroup so every affiliated radio retunes together. Because the frequency changes call to call, the talkgroup ID provides the stable identity that a human — or a scanner — tracks. Operators lock, prioritise, or mute talkgroups, and the system handles the frequency-hopping underneath.
Talkgroup IDs are numeric and system-specific. On P25 a TGID is a 16-bit value scoped to the system’s WACN and system ID; DMR uses its own numbering; and hobbyist databases publish human-readable alias tables mapping IDs to agency and function. A talkgroup usually carries group calls, but a system can also flag one as an emergency talkgroup for priority handling.
Variants
- Dispatch vs. tactical — some talkgroups are announcement/dispatch groups; others are short-lived tactical channels for an incident.
- Patched / multigroup — a dispatcher can temporarily merge several talkgroups into a patch or multigroup so they all hear one another.
- Announcement group — a supergroup that reaches every subordinate talkgroup at once, used for system-wide broadcasts.
In practice
Talkgroup planning defines how an agency is organised on the air: a mid-size city might run separate talkgroups for police districts, fire, EMS, public works, and events. Because a scanner following talkgroups can filter to just the ones of interest, monitoring by talkgroup is far more useful than watching raw frequencies. Priority scan lets a listener interrupt a lower-priority talkgroup when a chosen one becomes active.
Relevance to SDR
In GopherTrunk you follow talkgroups, not frequencies; each active call is shown with its talkgroup ID, any configured alias, and the transmitting radio ID. This lets you build allow/deny lists, prioritise groups, and log activity per talkgroup across a whole trunked system captured with one SDR.