Carroll County Patch Channel

[ed0202]

Has anyone else noticed A4 and A5 patch audio on the CC system is really bad? Ambulance to Hospital audio seems to be fine, but when the ER talks back, the audio is so distorted that you can not even understand what they are saying half the time. It's like a digitally distorted and over amplified version of Charlie Brown's teacher. From what I can tell, this isn't an issue on my end with the scanner because I constantly hear EMS personnel asking the ER to repeat.

 

[LeSueurC]

It’s probably because it’s patched to an UHF Med frequency

 

[rberg001]

It doesn't work that way. The county's 800 talkgroups are totally independent from the UHF system.

 

[LeSueurC]

It doesn't work that way. The county's 800 talkgroups are totally independent from the UHF system.

If that’s the case then in Cecil how come how I can hear Baltimore ambulances calling Shock Trauma and John Hopkins and Harford ambulances calling hospitals in Harford on Cecil’s EDACS system? Not because Cecil is calling those particular hospitals but because there is a patch somewhere along the line. I’m guessing some of the counties have there MED channels patched to UHF Med channels, thus why you get bad quality

 

[ocguard]

If that’s the case then in Cecil how come how I can hear Baltimore ambulances calling Shock Trauma and John Hopkins and Harford ambulances calling hospitals in Harford on Cecil’s EDACS system? Not because Cecil is calling those particular hospitals but because there is a patch somewhere along the line. I’m guessing some of the counties have there MED channels patched to UHF Med channels, thus why you get bad quality

No county's trunked system is patched to the UHF med system in any manner (if this is. being done, it's either out of error or laziness of the EMRC operator). When an EMS unit calls in on the CALL-1 channel and requests a hospital, the EMRC operator creates a patch between the assigned med channel and the requested hospital. If the county uses UHF, it'd be a UHF channel. If it's a TRS talk group, it'd be just that. The only reason TRS med talk groups are named similarly to the UHF channels is for familiarity.

What you MIGHT hear is the EMRC operator answering multiple jurisdictions on CALL-1, as every single CALL-1 medium (UHF and each Region 3 TRS talk group) are multi-selected for ease of operation.

 

[maus92]

No county's trunked system is patched to the UHF med system in any manner (if this is. being done, it's either out of error or laziness of the EMRC operator). When an EMS unit calls in on the CALL-1 channel and requests a hospital, the EMRC operator creates a patch between the assigned med channel and the requested hospital. If the county uses UHF, it'd be a UHF channel. If it's a TRS talk group, it'd be just that. The only reason TRS med talk groups are named similarly to the UHF channels is for familiarity.

What you MIGHT hear is the EMRC operator answering multiple jurisdictions on CALL-1, as every single CALL-1 medium (UHF and each Region 3 TRS talk group) are multi-selected for ease of operation.

So AACo has several MED channels assigned to their own TG. Are you saying this is basically simulcasting the corresponding EMRC MED channel, and used strictly for monitoring, by maybe the EMS duty officer?

 

[riveter]

EMRC is patching county resources to wireline hospital links. The UHF nets are mostly in this area for those entitites that might not have a local resource or working local resource to use.

 

[ocguard]

So AACo has several MED channels assigned to their own TG. Are you saying this is basically simulcasting the corresponding EMRC MED channel, and used strictly for monitoring, by maybe the EMS duty officer?

I'm saying that the AACo talk groups used to communicate with hospitals via EMRC are totally independent of the similarly names UHF med channels.

When a unit calls into EMRC's region 3 operator on Call-1 (whether it's on that county's trunked system, or UHF Call-1 AKA Med-9), the operator directs that unit to switch to the appropriate med channel (UHF) OR talk group. EMRC maintains base stations for each of the Region 3 county's med talk groups. If the unit call in will be completing their consult on a TRS talk group, the EMRC operator patches that talk group via wireline or microwave to the remote desk set at the receiving hospital. If the unit is using UHF, the EMRC operator patches the appropriate UHF med channel to the hospital's remote desk set using wireline or microwave. The UHF and TRS talk paths are completely independent of one another, and can be used simultaneously, by different EMS units, to complete consults to different hospitals.

It is POSSIBLE that, since AACo has only recently (not sure exact timeline) begun to use the TRS for EMRC communications, the the region 3 operator may simply patch the TRS talk group and the UHF channel together with the hospital's desk set to avoid confusion, but this is NOT the standard NOR permanent.

If every county's EMRC talk groups (which mirror Med-4 and Med-8) were reliant on the UHF Med-4 and Med-8 infrastructure to complete consults, that would mean that there could only ever be two consults occurring in region 3 at any one moment, which is obviously not viable.

 

[maus92]

So assuming that 2 county medic units are working separate calls, then seems that it is *possible* for MU1 to be using UHF MED4 and MU2 to be using the county TRS MED4 simultaneous, since they are not bridged together, correct? Not that you would typically do that in practice unless somehow out of resources?

 

[riveter]

It's entirely possible.. and the only reason it wouldn't be done in practice is because they'll tend to use their TRS nets for the purpose almost exclusively as long as they work, out of convenience.

 

[Dispatcher308]

So assuming that 2 county medic units are working separate calls, then seems that it is *possible* for MU1 to be using UHF MED4 and MU2 to be using the county TRS MED4 simultaneous, since they are not bridged together, correct? Not that you would typically do that in practice unless somehow out of resources?

That is correct, the UHF and 800 systems are in no way patched. It can be done whatever way the field provider wants to do it, EMRC operators are not picky, heck they can even call in on the phone and EMRC can patch them.

As ocguard has stated the only reason why you hear the EMRC Operator on Call 1(UHF), and 800mhz TG's AA- Call 1, BC - Call 21, BCo Call 221, CR A4 Call 801, HAR Call 301, HOW Call 1 is because the operator has it multi selected at the console.

Also I would listen to rberg001 as he is the man, the myth and the legend

 

[maus92]

Interesting stuff, thank you.

Is there a physical / logical limit to how many consults can be routed through EMRC at any one time? Any limitations on interface type, like EMRC has x number of incoming lines, x number of radio ports, etc?

 

[Dispatcher308]

Yes there is a limit but we don't give those trade secrets away!

 

[Dispatcher308]

I'm saying that the AACo talk groups used to communicate with hospitals via EMRC are totally independent of the similarly names UHF med channels.

When a unit calls into EMRC's region 3 operator on Call-1 (whether it's on that county's trunked system, or UHF Call-1 AKA Med-9), the operator directs that unit to switch to the appropriate med channel (UHF) OR talk group. EMRC maintains base stations for each of the Region 3 county's med talk groups. If the unit call in will be completing their consult on a TRS talk group, the EMRC operator patches that talk group via wireline or microwave to the remote desk set at the receiving hospital. If the unit is using UHF, the EMRC operator patches the appropriate UHF med channel to the hospital's remote desk set using wireline or microwave. The UHF and TRS talk paths are completely independent of one another, and can be used simultaneously, by different EMS units, to complete consults to different hospitals.

It is POSSIBLE that, since AACo has only recently (not sure exact timeline) begun to use the TRS for EMRC communications, the the region 3 operator may simply patch the TRS talk group and the UHF channel together with the hospital's desk set to avoid confusion, but this is NOT the standard NOR permanent.

If every county's EMRC talk groups (which mirror Med-4 and Med-8) were reliant on the UHF Med-4 and Med-8 infrastructure to complete consults, that would mean that there could only ever be two consults occurring in region 3 at any one moment, which is obviously not viable.

Matt is correct here! And explains the process in the most simplistic way! But since he is just a Paramedic we will not give him any credit for his answers!

 

[ed0202]

First, thanks for the explanation and the screen shots. I am by no means an expert on any of this, but I am really interested in learning more. This was far more information that I could have hoped for, but much appreciated. If I'm understanding this correctly, when I hear A4 on the scanner, I am listening directly to the audio on a trunked voice channel on the Carroll trunking system, and in the case of A4, I believe this is a regular Phase 1 talkgroup. I think you are saying that there is an MCC dispatch console on that system that has a multiselect set up between A4 and some other resource that is at the hospital. That resource must be some sort of analog channel or phone patch because it wouldn't make sense for it to be any trunked resource on the Carroll system. Since the audio I hear is only poor on the hospital side, this would mean that the multiselected resource is the source of the problem and understanding it any further than that would require a discussing with the technicians running the Carroll system? I'm surprised that they would even tolerate such bad audio, but maybe this is as good as they can get it for whatever reason.