QC-II on a Trunking System?

[PropellorHead]

I have an XTS-5000R Model III with v12 firmware.

Is it possible to have the radio VMUTE or activate for QC-II tones on a trunking talkgroup? I know that you can obviously do it on conventional, but I'm wondering if there is a way to set it up on a trunking personality.

Thanks in advance!

[akardam]

I'm pretty sure Motorola subscribers won't let you associate QCII on anything but conventional, though there may be other products out there that would let you do it. Most people just use the built-in trunking signalling features.

[RKG]

The function of QC tones is to enable the sending radio to control some function on the receiving radio(s). The means of encoding the command is the frequency and timing of the tones.

For a trunked system, there is no need of tones. Assuming the same control function is authorized and programmed in both the system controller and the subscriber units in question, the commands are sent (and, as appropriate, acknowledged) by sending data commands over the control channel.

Take an illustrative example. SelCall (selective calling) is a means of opening the audio squelch of only one (or a sub-group) of the subscribers who are the members of a logical channel (as opposed to dispatch calling, which opens audio in all of the member subscribers). Using QC in a conventional analog system can achieve this by sending tones that only some receiving subscribers are programmed to respond to. In the trunked world, the initiating subscriber sends an "inbound service word" (ISW) to the system controller that contains: the subscriber ID, the system ID, the ID of the subscriber (or group of subscribers) with whom the initiator wishes to confer, and a codeword that requests a voice channel assignment for an individual call. The system controller, if it approves the request, sends an outbound service word (OSW) over the control channel. The OSW contains the system ID, the ID of the initiator, the ID of the target subscribers, a hexadecimal integer the identifies the frequency of the assigned voice channel, and a codeword that instructs the targets, but only the targets, to shift to the voice channel.

So QC won't work over trunked systems, but there is no need for it, since the same functions can be performed by data commands directly.

Hope this helps.

[Bill_G]

Excellent discussion so far. I would add it also depends on what feature sets have been enabled in dispatch, and the goals of the system administrator. I would talk to you coordination group, or whomever is responsible for the overall functionality of your system, to see what is available.

[DPL]

Though it seems that the OP's question has been answered already, it is worth noting that QCII *is* used on trunking systems for fire station alerting in some cases. In these cases the tones are generated by some device tied to the transmitting radio (e.g., a console), and decoded by a separate box attached to the receive radio. So, in accordance with what was mentioned by previous posters, the trunking system and subscriber radios themselves do not provide this functionality, but it is provided by external devices connected to the radios. I have never quite understood why this is done, unless it is just ignorance of the trunking system features described in the above posts.

[RKG]

Though it seems that the OP's question has been answered already, it is worth noting that QCII *is* used on trunking systems for fire station alerting in some cases. In these cases the tones are generated by some device tied to the transmitting radio (e.g., a console), and decoded by a separate box attached to the receive radio. So, in accordance with what was mentioned by previous posters, the trunking system and subscriber radios themselves do not provide this functionality, but it is provided by external devices connected to the radios. I have never quite understood why this is done, unless it is just ignorance of the trunking system features described in the above posts.

Good point. Actually, I was aware of this, but I interpret the QC tones to be not "used" by the trunked system, since the trunked system is simply conveying them as a form of analog information to be used by something else.

As for the "why," as far as I can tell the answer lies in a mix of simple inertia plus the continued use of Minitors. (Often the QC is simulcast both over the trunked system and a legacy paging freq.)

[Bill_G]

That, and legacy support of station tapout. A lot of investment in getting bay doors up, quarters lights on, killing kitchen stove power, and activating the overhead PA. Some of it is converting to remote control via dsl to a plc panel. A lot of it is still good old fashioned Plectron-esque T&V tapout to a box someone Tom Edisoned with a bucketful of contactors.

[ai4ui]

Another reason is expense. For those of us that are paying subscription fees for trunked radio, it is much cheaper - up front & on going -to maintain a VHF base station & a fleet of minitors than it is to pay the monthly expense of a radio (or radios for volunteer contract stations) and provide everyone at the said volunteer stations with a radio.

QC is reliable, efficent, & cost effective.

At least that's how I see it...

[akardam]

Another reason is expense. For those of us that are paying subscription fees for trunked radio, it is much cheaper - up front & on going -to maintain a VHF base station & a fleet of minitors than it is to pay the monthly expense of a radio (or radios for volunteer contract stations) and provide everyone at the said volunteer stations with a radio.

QC is reliable, efficent, & cost effective.

At least that's how I see it...

Except that bypasses the trunking system completely, which is not what the OP originally required about.

[ai4ui]

True...

this was more of a reply to RKG's comment about the continued use of simulcasting & minitors.

[RKG]

In Massachusetts, most of the fire departments on Cape Cod switched from low band to the State's 800 trunked system, on a subscription basis. However, many retained their old systems, some just for pages and some for both pages and voice, with everything just simulcast on both the low band and the trunked. My guess is pure inertia.