Montgomery Co Hospitals

[md_p97]

So I recently started listening to medic/hospital comms in Mont Co.

When the medic calls EMRC and requests a patch (On Mont Co;s SmartZone system) I hear both sides of the conversation between the hospital and the mobile unit just fine. (TG's 4176, 4208, 4240)

But I also added the TG for the Hospitals themselves (e.g. TG 4368 Shady Grove). I can hear the hospitals talking back to the ALS/BLS units, but I can't hear any comms from the mobile units themselves.

Is there a separate vhf/uhf freq being used, and the TG is just a simulcast of the hospital?

At any rate, I would like to get the freq(s) being used if anyone can help me out.

Thanks.

 

[md_p97]

I did just find the med channels under EMRC on the Md .db page. Maybe I just solved my own issue.


Edit:

Hmmm....No joy. I added the UHF Med Freq's to my scanlist. Just heard Suburban on their TG talking to a mobile unit in the field, nothing came across the med channels.

 

[emtLarmy15]

While I am not directly familiar with MoCo system, the UHF channels are full duplex meaning transmit on one freq and receive on another. From my days riding in the ambulance you only heard the hospital not the ambulance on the uhf. I suspect what you’re hearing on the MoCo system is MoCo units using their system which is more than likely patched into a UHF radio. I think you will eventually see the UHF system retired in favor or FiRST. MIEMSS recently got budget money to bring its infrastructure up to date.

Hope this makes a little bit of sense.

Edit: the above fails to mention that the mobiles on uHF transmit and receive on different frequencies and the base stations at EMRC use same frequency but in reverse, so in the mobile environment you only hear the base station (EMRC and wherever they pitch you into).

The MoCo system is most likely patches directly to a uHF radio (acting as a mobile) the reason you hear the ambulance is they’re talking on the trunked system. If a unit was to use the UHF radio you would only hear the hospital side of the conversation even on the trunked system patch.

 

[maus92]

As far as the EMRC UHF Med channels go, they are indeed full duplex as explained. It's likely you will not hear the provider (EMT / Paramedic) side of the transmission unless you are close to the unit in the field. The hospital side transmits from voted / steered tower sites with more powerful radios and higher antennas which is why you generally always hear them.

As far as the county 800 TRS is concerned, we just had a similar conversation about the Carrol County set up. The TRS "Med" channels are totally independent of the UHF EMRC Med channels - even if the share the same number. Theoretically one field unit could be talking on UHF Med 1 to Holy Cross, and another unit could be talking to Shady Grove on the TRS Med 1 and not interfere with one another. EMRC can route conversations from either the UHF system or various county radio systems to the appropriate resource.

As for the hospital TGs on Montgomery's 800 TRS - not sure what they are for.... But I would *expect* it would be a half-duplex channel like any other TG on the 800 system. Maybe it's similar to the old 155.340 EMS channel they used to have that was not routed through EMRC, IDK. Or possibly a backup for the direct telephone line between each hospital and the EOC.

Also, MIEMSS plans to maintain their own separate UHF system and not migrate to FiRST.

 

[md_p97]

While I am not directly familiar with MoCo system, the UHF channels are full duplex meaning transmit on one freq and receive on another. From my days riding in the ambulance you only heard the hospital not the ambulance on the uhf. I suspect what you’re hearing on the MoCo system is MoCo units using their system which is more than likely patched into a UHF radio. I think you will eventually see the UHF system retired in favor or FiRST. MIEMSS recently got budget money to bring its infrastructure up to date.

Hope this makes a little bit of sense.

Thanks for the quick reply. I comprehend what you both of you are saying, but I don't think that is what is occurring.

Each hospital on MC's 800mhz TRS has its own dedicated talkgroup. I hear the hospital side of the conversation on that TG. If it is a simulcast of the 463.XXXX then why not simulcast the mobile side 468.XXXX?

Also, this is a separate from the "patch" where the mobiles and hospitals are connected. I only hear those conversations on the Med-1, Med-2 dedicated TG. And, if the patch was indeed connecting the 463/468.XXXX pairs, I should be able to hear at least the hospital on the UHF freq's in my scanlist even if the mobiles are too far away. And, since all 6 of Mont. Co's hospitals share the same 3 463/468.XXXX med channel pairs, how would the TRS system know which hospital to simulcast on which dedicated TG?

I did hear a couple two sided conversations on Suburban hospitals dedicated TG last night which means the mobiles have the ability to use the hospitals TG's in the field. (Suburban is Mont Co's only trauma center, perhaps that's the reason). If the mobiles can talk directly to the hospitals on the hospitals dedicated TG, then why use UHF OR the EMRC Patch at all?

 

[emtLarmy15]

Ahh I am following now... and I am working on it in my head. There has to be a logical answer. I suspect each hospital has it’s own TRS talkgroup for patch purpose. While it may seem easier to just put several talkgroups in they may be limited in the ambulance radio and for convenience they just use a med channel set up and then patch to the appropriate hospital talkgroup.

This doesn’t explain why you only hear one side but I think I finally understand the setup.

 

[maus92]

Read this thread for some answers:

https://forums.radioreference.com/m...orum/377503-carroll-county-patch-channel.html

 

[md_p97]

Read this thread for some answers:

https://forums.radioreference.com/m...orum/377503-carroll-county-patch-channel.html

Thanks for that, a nice comprehensive thread on how EMRC and the Patches work.

But what about when no patch is used? The mobiles have the ability to talk directly to the hospital of their choosing, I would think that is most likely being done on a UHF freq, But it can't be on the dedicated MIEMSS channels, as I have those loaded in my scanner, and at the very least, I should be able to hear the hospital side of the conversation even if the mobiles are too far away.

I did go to the FCC .db and look up the freq's being used at each hospital. Each of the hospitals has their own 463/468.XXXX pair listed, but none of the pairs match the MIEMSS dedicated channels also paired on 463/468. I added the new pairs into my scanlist, still no joy!

So my question is: If it's not the dedicated MIEMSS UHF freq's then what freq or TG ID are the mobile units using to talk directly to the hospitals when the patch ISN'T being used?

REF:
ULS License - Industrial/Business Pool, Conventional License - WQLM995 - Suburban Hospital - Frequencies Summary

ULS License - Industrial/Business Pool, Conventional License - WPGA816 - HOLY CROSS HOSPITAL - Frequencies Summary

ULS License - Industrial/Business Pool, Conventional License - WPUR630 - Montgomery General Hospital - Frequencies Summary

 

[emtLarmy15]

OCguard is not correct in that thread. Worcester TRS is patched directly to UHF. I only read that far.

 

[maus92]

Thanks for that, a nice comprehensive thread on how EMRC and the Patches work.

But what about when no patch is used? The mobiles have the ability to talk directly to the hospital of their choosing, I would think that is most likely being done on a UHF freq, But it can't be on the dedicated MIEMSS channels, as I have those loaded in my scanner, and at the very least, I should be able to hear the hospital side of the conversation even if the mobiles are too far away.

I did go to the FCC .db and look up the freq's being used at each hospital. Each of the hospitals has their own 463/468.XXXX pair listed, but none of the pairs match the MIEMSS dedicated channels also paired on 463/468. I added the new pairs into my scanlist, still no joy!

So my question is: If it's not the dedicated MIEMSS UHF freq's then what freq or TG ID are the mobile units using to talk directly to the hospitals when the patch ISN'T being used?

REF:
ULS License - Industrial/Business Pool, Conventional License - WQLM995 - Suburban Hospital - Frequencies Summary

ULS License - Industrial/Business Pool, Conventional License - WPGA816 - HOLY CROSS HOSPITAL - Frequencies Summary

ULS License - Industrial/Business Pool, Conventional License - WPUR630 - Montgomery General Hospital - Frequencies Summary

Those hospital licensed business / industrial UHF frequencies are for internal use, not for field communications.

County EMS units use the county's TRS and EMRC UHF Med channels. They are not equipped nor licensed to use IG business / industrial UHF frequencies.

Prior to the TRS, Montgomery County EMS units used VHF simplex 155.340 aka "EMS1" to consult with hospitals, mainly for routine, non-critical transports. These transmissions were not controlled or routed through EMRC. The procedure *was* the EMS unit contacted Montgomery EOC, and the EOC would call the hospital on their direct telephone line for them to come up on "EMS1" (I think that's what it was called back in the 1990s.) I'm thinking the current hospital TGs are analogous to the EMS1 channel used back in the day, but I'm not sure why you are hearing only the hospital side on the conversation when monitoring the TG. Note that it would be difficult to receive the field units unless they were nearby on VHF.

MIEMSS licenses the UHF frequencies and operates the network backbone that links all the transmit/receive sites together (the counties also license the UHF freqs - or used to.) They use UHF frequencies in the Public Safety Conventional pool, not IG frequencies as your links show. Transmit sites can be co-located at hospitals, but hospital consoles are linked to EMRC which then routes to the appropriate transmit site.


Also, there is a fire captain that works for Montgomery County DFRS communications that posts here sometimes. Maybe he will chime in and clear up any questions.

 

[Dispatcher308]

Those talk groups on the Montgomery system to the just the Hospitals are used exclusively by the County and do not go through EMRC, they may have the field units encrypted so you can't hear the field reports and you may only hear hospital. They are for priority 3 consults only, if there is a higher priority they must consult through EMRC.

 

[Dispatcher308]

Ahh I am following now... and I am working on it in my head. There has to be a logical answer. I suspect each hospital has it’s own TRS talkgroup for patch purpose. While it may seem easier to just put several talkgroups in they may be limited in the ambulance radio and for convenience they just use a med channel set up and then patch to the appropriate hospital talkgroup.

This doesn’t explain why you only hear one side but I think I finally understand the setup.

Worcester is the only oddball, OCGURARD was 99% correct!

 

[emtLarmy15]

The reason Worcester did it into uhf is when orders are needed they have to go through EMRC and rather than go back to the unit they can do it right on their county portable radio. 90% of the time going to AGH they use the AGH talkgroup on the TRS. Going to PRMC I don’t think they do much of anything with a priority 3.

 

[maus92]

The reason Worcester did it into uhf is when orders are needed they have to go through EMRC and rather than go back to the unit they can do it right on their county portable radio. 90% of the time going to AGH they use the AGH talkgroup on the TRS. Going to PRMC I don’t think they do much of anything with a priority 3.

What? No dual band Harris portables for the medic units?

 

[Mr_Boh]

MoCo is in the process of converting the hospital talkgroups that are specific to their trunked radio system to fully encrypted. So as was speculated, mobiles are encrypted but not all the hospitals are yet. Hence half the conversation.

The EMRC consult channels are direct patches to EMRC. Hence if you listen to what Montgomery calls “72 Charlie” on their system you can hear PG and Frederick units requesting consults from their respective systems but you will only hear the EMRC side. So if you are holding on it, you will hear “Med Alpha, Med Alpha” out of the blue. That’s the return from EMRC telling a PG unit to switch to their Med A talkgroup for consult.

Finally a word about MoCo EMS operations. Not every consult is through EMRC. Units can flip right to the hospital-specific talkgroup and say something like “Ambulance Seven oh Whatever to Holy Cross Germantown” and wait for the staff there to chime up. Then they will give a brief heads up of what they are bringing. There’s nothing that says a unit can’t go through EMRC for their low priority sick person call, but typically more routine stuff is on the dedicated talkgroup where more unusual stuff is on EMRC - again, not the rule, just typical ops. Units pretty much have to use EMRC if they need true consultation (doctor), have a high priority/special case call (ie stroke alert), or need to reach a hospital that doesn’t have a talkgroup but EMRC can patch (most hospitals in and near MD boundaries).

 

[maus92]

MoCo is in the process of converting the hospital talkgroups that are specific to their trunked radio system to fully encrypted. So as was speculated, mobiles are encrypted but not all the hospitals are yet. Hence half the conversation.

The EMRC consult channels are direct patches to EMRC. Hence if you listen to what Montgomery calls “72 Charlie” on their system you can hear PG and Frederick units requesting consults from their respective systems but you will only hear the EMRC side. So if you are holding on it, you will hear “Med Alpha, Med Alpha” out of the blue. That’s the return from EMRC telling a PG unit to switch to their Med A talkgroup for consult.

Finally a word about MoCo EMS operations. Not every consult is through EMRC. Units can flip right to the hospital-specific talkgroup and say something like “Ambulance Seven oh Whatever to Holy Cross Germantown” and wait for the staff there to chime up. Then they will give a brief heads up of what they are bringing. There’s nothing that says a unit can’t go through EMRC for their low priority sick person call, but typically more routine stuff is on the dedicated talkgroup where more unusual stuff is on EMRC - again, not the rule, just typical ops. Units pretty much have to use EMRC if they need true consultation (doctor), have a high priority/special case call (ie stroke alert), or need to reach a hospital that doesn’t have a talkgroup but EMRC can patch (most hospitals in and near MD boundaries).

Thanks for the clarification MB - seems like there is some patching going on after all (at least in a few counties.) I suspected the hospital TGs had a function similar to the old EMS1 VHF channel that was used back in the day.

 

[dwlipp]

Ding, ding, ding, we have a winner

Those talk groups on the Montgomery system to the just the Hospitals are used exclusively by the County and do not go through EMRC, they may have the field units encrypted so you can't hear the field reports and you may only hear hospital. They are for priority 3 consults only, if there is a higher priority they must consult through EMRC.

The zone 79 talkgroups are transport notification talkgroups and are internal to the MC trunked radio system; they do not involve EMRC, patching or any other frequencies. The field subscribers are all encrypted on these talkgroups, so you will never hear the field units talk to the hospitals. The hospitals are configured to both RX and TX clear, this is so mutual agencies that don't have secure radios can still use these talkgroups for transport notifications if they are so inclined.

So the punchline is if you listen to the zone 79 talkgroups you will just hear the hospitals saying basically "ok" or "go away"; you will never hear any MCFRS units talking to the hospitals. If you happen to be listening when a mutual aid unit is making a transport notification on a zone 79 talkgroup you will hear both sides of the conversation if they are not using a secure capable radio.

There is no plan to encrypt the hospital's side of the conversation at any point in the future; basically all they say is "ok" or "go away" to some generally unknown unit so not much is being given away there...

BTW, our EMRC patch talkgroups are clear, just like the entire EMRC radio system.

Hope this helps.

Dallas

 

[motorcoachdoug]

9 times out of 10 i am able to pick up both the mobile unit and the hospital in the 79zone. I live right by MCFD station 25 and i can hear both when they talk to Montgomery General and HCH Silver Spring as well. Most of the times i even hear unites up county talking to HCH Germantown and talking to WAH as well. A lot of PG units also talk to WAH and i have the software to listen to them as well. In regards to EMRC i do hear them on 72C and then also on 72D and or 72E which is the county TG when they are doing a stroke alert ,need to talk to a doc and or any level 1 and or level 2 trauma as well. I brought a 800mhz antenna to aim at the Howard County tower since Monkey has not yet gotten their own tower on the MD 1st system yet unless i dont know about it but I am picking up the MD 1st system as well. So between the dipole antenna and the 800mhz antenna I am able to cover just about everything...

 

[maus92]

9 times out of 10 i am able to pick up both the mobile unit and the hospital in the 79zone. I live right by MCFD station 25 and i can hear both when they talk to Montgomery General and HCH Silver Spring as well. Most of the times i even hear unites up county talking to HCH Germantown and talking to WAH as well. A lot of PG units also talk to WAH and i have the software to listen to them as well. In regards to EMRC i do hear them on 72C and then also on 72D and or 72E which is the county TG when they are doing a stroke alert ,need to talk to a doc and or any level 1 and or level 2 trauma as well. I brought a 800mhz antenna to aim at the Howard County tower since Monkey has not yet gotten their own tower on the MD 1st system yet unless i dont know about it but I am picking up the MD 1st system as well. So between the dipole antenna and the 800mhz antenna I am able to cover just about everything...

FIRST is receivable in Montgomery County from some Howard, Frederick and AA County sites - depends on where you are. THe system *wants* to build a tower site along the ICC @ Georgia Ave, by they seems to be a NIMBY issue - not sure if that has been resolved. The DC area is supposed to be operational by the end of this year.

 

[rberg001]

Here is something for the curious types....