slicerwizard
Member
Technically, what your scanner sees on the outbound control channel is actually the system acknowledging an affiliation sent by a radio, but it's convenient and accurate enough to call it an affiliation command. Radios affiliate when they start monitoring a site's control channel (e.g. the radio was just turned on, or the radio just roamed from another site, or the radio had been on a conventional channel and the user switched to a trunked talkgroup), or when the user switches from one talkgroup to another, or when the system tells the radio to affiliate.fpo701 said:
"Scanning" implies monitoring multiple talkgroups simultaneously; affiliations and scanning do not relate to each other. An affiliation tells you the specific talkgroup the user has selected via the zone/channel controls.
Patch OSWs announce the joining of two or more of a system's talkgroups. Patches between separate systems do not generate patch announcements.
Affiliations have already been covered. An affiliation request is generated by the trunking system when it wants to know what site (more properly, what zone) a radio is monitoring and what talkgroup the user has selected. A radio will respond to an affiliation request by affiliating.
The reasons for issuing an affiliation request:
- on a SmartZone system, a radio has generated no traffic for 4 hours; if the radio is no longer monitoring (e.g. battery died, etc.), there is no need to send voice traffic for whatever talkgroup that radio was monitoring to that zone if no other radios on that zone are affiliated to that talkgroup. The affiliation request will only be broadcast on the last zone the radio was seen on. If the radio responds by reaffiliating, the site will continue carrying audio for the talkgroup the radio is monitoring for an additional 4 hours. As long as the radio keeps responding to affiliation requests, the cycle will repeat every 4 hours. A portable radio left on in a charger or a base radio left on overnight will trigger these repeated affiliation requests.
- on a SmartZone system, a trespassing radio (e.g. a radio from some other trunking system) has affiliated to the system and then said "Oops, my bad - this isn't my system; gotta go - bye" and now the system needs to know where its authorized radio is and what talkgroup it's monitoring. This request will be broadcast on all zones.
- a radio is requesting a voice channel grant, but hasn't told the system what talkgroup it is using. When a user presses the PTT button, the radio just tells the controller "I'm the radio using RID xxx and I want to talk to my group"; the talkgroup number is not included in the request. Normally, this isn't a problem, since the system remembers the last talkgroup the radio affiliated to. However, if the user has just powered on the radio and then quickly keyed up before the radio has had time to affiliate, the radio may fail (depends on the radio/firmware) to tell the system what talkgroup it is on.
- someone in a supervisory position tells the system to ping the radio. This can be used to figure out which zone a radio is in and what talkgroup it is monitoring. Repeated pings can be used to track down a lost or stolen radio.
Those are separate commands; the former broadcasts the system's ID (SysID) and the current control channel frequency index. Radios use it to verify that they are monitoring the correct system, e.g. not trespassing. The ten low order bits of the last value (28CC) define the CC index, so the actual value seen can range from 2800 to 2BFE.
The 308/30B dual-OSW that ends with 261B is an entirely different command, as noted. If it ended in 261C, it would mean something else yet again.
Non-SmartZone systems probably only use the 308/310 version. Some SmartZone systems use 308 and some use 309.
Non-SmartZone.
No prob.
