Charleston Co. Dispatch Changes

[evan]

The old "North Zone Dispatch" channel (TG 2050) is now called "EMS Ops" . The old "South Zone Dispatch" channel (TG 2051) is now called "County Dispatch" The county dispatch channel is being used to dispatch all calls for EMS and for multiple fire departments (Charleston FD, James Island, St. Andrews, Johns Island, Awendaw, and maybe some others). The dispatcher is initiating a cross-patch between this channel and the dispatch channels of each agency being dispatched to that specific call. Official users of the system will not notice any difference. However, scanner users will have to monitor the county dispatch channel to receive the dispatch traffic since our scanners don't know how to interpret cross-patches.

The County Dispatch channel is being used for the initial dispatch only. At the end of the transmission, the dispatcher will tell the units what channel to respond on: EMS Ops for routine EMS calls (including FD first responders) or one of the incident channels for larger incidents. I have not heard any mobile units using the County Dispatch channel.

 

[AlphaDelta10]

So are you telling me by 2050 being "EMS Ops" that they are going back to how it used to be on the old analog system with one ID (1936) being the EMS channel where ALL EMS calls are dispatched? And 2051 is just where FD's monitor to get there calls before they go the incident channel, right? Just wanting to make sure. Every since they did this fustercluck with the FDs and EMS, I've stop bothering to even try to understand. I have all of the EMS, Fire, and incident channels in my scanner so it didn't really matter before because I scanned them all anyway. It's just nice to know now how it all works.
Thanks!

 

[evan]

All EMS and FD calls (those FDs dispatched by the consolidated dispatch center?) are dispatched on the County Dispatch channel. Depending on the agencies that are responding to the call, the County Dispatch channel is cross-patched to the corresponding Ops channel of each department. This allows each department to leave their radio on their own channel and still receive calls that appear to us scanner users to only be coming across the County Dispatch channel.

For example if there is a structure fire, and St. Andrews, Charleston, James Island and EMS are dispatched on the call, the dispatcher cross-patches the County Dispatch channel with St. Andrews Ops, JI Ops, Charleston FD Ops, and EMS Ops. Each department will hear the call on their own channel because their radios "know" how to interpret cross-patches. This also reduces system resources as only one frequency on the system is required to send a call to multiple agencies on different talkgroups. Our scanners only recognize the "main talkgroup" in the patch, which is County Dispatch. Johns Island, on the other hand, would not hear the call since they are monitoring their own Ops channel and the dispatcher did not add them to the cross-patch since they aren't being dispatched to the call. If the dispatcher adds their Ops channel to the cross-patch, they would hear the transmission without having to change channels on their radio.

For scanner users, you can monitor the County Dispatch channel and hear dispatches for multiple FDs and all EMS calls without having to scan their other channels and hear routine traffic (arrivals, enroute, etc).

Does that make sense?

 

[brian]

The PRO-106/PSR-500 had a recent firmware update that added support for patches. I've seen it on certain SCHP talkgroups on Palmetto 800 that are patched together. Does that not work on P25 systems?

 

[evan]

I have seen PTCH appear on my PSR-500 while monitoring the P25 system but never with the situation I described above. The only way I know the above situation is a patch-type situation and not units simply monitoring County Dispatch is by watching it on Unitrunker.
Apparently there are some subtleties with different types of patches/multi-selects initiated by a dispatcher that are interpreted differently by the PSR-500. I don't have enough technical knowledge of trunked systems to definitively say any more. I can only speculate that what I called a "cross-patch" above is technically a multi-select situation where the dispatcher's transmission is heard across all channels involved in the multi-select (1 way) as opposed to a true cross-patch where all units on all channels involved in the patch hear each other (more two-way). I used to be able to distinguish these on 3600 systems with the old dos trunker. I'm not sure how to distinguish the two on Unitrunker. In the call history box it shows, for example, "County Dispatch" under source, "Adds" under action, and "Charleston FD Ops" under target.

The times I've seen PTCH appear on the PSR-500 while monitoring the P25 system occurred when Folly Beach PS was cross-patched with SO West Dispatch.

 

[AlphaDelta10]

Thanks Evan! I got it now. About two hours after I wrote that post, my computer died on me and I got another one yesterday. Windows 7 is a world of different from XP! For the better that is. Thanks for response!