Could Someone Explain Patching In Relation to Trunking?

[Mikey]

OK ... I've been following the various trunked systems around town for a number of years now (since the BC235 came out). There's something I just don't get in relation to following trunked systems on scanners - That is when talkgroups are patched together. Maybe I'm missing something easy, but I just don't understand

Now, I would assume that I should be able to hear traffic on BOTH of the patched talkgroups when that happens, but that is not necessarily the case. For example, when the SO has Poway and Rural patched (as is often the case), I will either hear traffic on Rural Disp or Poway Disp, but never both. The same goes for the recent fluctuation in SDFD dispatch talkgroups and SO Lemon Grove and Imperial Beach dispatches.

That said, the other day SDPD Mid-City patched with City Tac 3 and I heard traffic on BOTH talkgroups.

I would assume the units in the field are just on whatever channel they're normally on and not flipping to the various dispatches ... Is this just a side effect of how the current trunking scanners decode the data? Can it be fixed? Or is it just me?

I assume I have the Status Bit options set correctly on my scanners (the current ones I use mainly are a BC296 and a BC246T) otherwise I wouldn't hear traffic on the patched channels in the first place.

Help?

- Mike

[jp186]

When the talkgroups are PATCHED, you will hear the both sides on both talkgroups. Sometimes I think people refer to talkgroups as being patched when they are not patched, but are multi-selected by the dispatcher and being talked on by the dispatcher ONLY at the same time. A dispatcher could select 2 or more talkgroups at one time, and broadcast on all those talkgroups at the same time, but you will not hear traffic from the other talkgroups. When the dispatcher transmits the talkgroup will have a different ID than normal, but when the field unit talks it will not.

An example would be when Heartland does the morning page/radio test at 0815 every day. The dispatcher selects HND Disp, HND Disp 2, and NAT Command 6 on a multi-select. The dispatcher transmits on all 3 channels at the same time. But if a field unit were to transmit on any one of those talkgroups during that time, it would not be broadcast across the other two talkgroups. If those channels were PATCHED, you would hear a field unit on all 3 channels if they transmitted on any one of them.

Hope this helps.