Simulcast and linking of GMRS repeaters

[WRHT379]

Good day Fellow Enthusiasts,

  My name is Tony the Chief Radio officer for Sonoma County Neighborhood Auxillary Communication Service(non agency, volunteers). We have created a 20 plus repated system here using the Motorola SLR5700 series repeater. we have deployed 1000's of radios to neighborhoods and teach resilency and self preservation using GMRS/Amateur/Cup and string/smoke signals/bullhorns you name it we will try it,  to communicate. I understand that we have very few GMRS frequenciesto use and we want to be good stewards to our neighboring counties. So i want to simulcast to minimize power output and fequency usage. We also plan to install backbone and redundancy using ubiquitous and LoRa radio. i am asking you good people for advice,  reference material and/or experiences in how you have done this. Presently i am looking at using the RTCM thin client or a stand alone RPI. I know my way around a RPI enough to ge tmyself in trouble and would prefer a more plug n play approach. of course money is a big consideration since we are a volunteer group.

i apprecaite you folks for doing what you do providing that redundancyfor your communities

 

Tony Goodwin

Chief Radio Officer: Sonoma County Neighborhood Auxillary Communication Service

Sonoma County, CA.

[nokones]

The Southwest Community Radio System (SWCRS) has two separate simulcast systems. I believe both are a three site system with one in the Tucson Area and one in the Albuquerque Area. You can reach them at swcrs.org or tucsongmrs.org for the specifics of their systems.

They have the Tucson system phased pretty good very seldom do I here any wah wahs and warbles.

[tweiss3]

Simulcast is not cheap. You can "roll your own", still about $1000+/site with https://allstarsimulcast.com/. Note, you cannot link into Allstar/Echolink.

Second option, which is widely commercially available is JPS: https://jps.com/products/snv-12/

I would also suggest you reach out to your Motorola vendor and discuss if there is a Moto solution to simulcast on analog for your chosen hardware.

[nokones]

Tony:

You should consult with the Sonoma County Communications Department. I'm not sure if the Sheriff is still on UHF, I believe their system is still a simulcast system.

[kidphc]

If we are discussing simulcast, and lora back bones/ radio.

Why is the group not talking to the local pd. Who probably has simulcast already set up. Old gear that can be repurposed, get potential federal grants and be administered ( really only sounds like you need 1-2 tac groups). As well as the license for the extra frequencies. Probably can be encrypted as well.

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[TDM827]

Linking GMRS repeaters is entirely possible. If someone in your group is willing to search "linking repeaters" in the My GMRS forum they will find good information on what's involved, generally, and how GMRS users enjoy, or dislike, linked repeaters.

Just not sure if it will fit into your overall plan.

Perhaps you could share how you see fitting GMRS into, or interfacing, with your communication plan for the county. With more specifics you would likely get some more targeted guidance.   

A good place to start is here..

 

 

[WRHT379]

6 hours ago, tweiss3 said:

Simulcast is not cheap. You can "roll your own", still about $1000+/site with https://allstarsimulcast.com/. Note, you cannot link into Allstar/Echolink.

Second option, which is widely commercially available is JPS: https://jps.com/products/snv-12/

I would also suggest you reach out to your Motorola vendor and discuss if there is a Moto solution to simulcast on analog for your chosen hardware.

Thanks, I did reach out to them. I was pretty disappointed in purchasing vendor when I found out we couldn't link our analog channels. The whole reason we went this route with Motorola was the ease of linking(if only GMRS was digital). Thanks for your feedback

 

Tony

[WRHT379]

1 minute ago, WRHT379 said:

Thanks, I did reach out to them. I was pretty disappointed in purchasing vendor when I found out we couldn't link our analog channels. The whole reason we went this route with Motorola was the ease of linking(if only GMRS was digital). Thanks for your feedback

 

Tony

Oh and they recommended RTCM for our solution. 

 

Tony

[WRHT379]

5 hours ago, nokones said:

Tony:

You should consult with the Sonoma County Communications Department. I'm not sure if the Sheriff is still on UHF, I believe their system is still a simulcast system.

Actually we are trying to work with the them but they are stubborn.  The whole reason we started NACS was to support the community that wasn't being supported by the Sheriff and other agencies. This movement is for the people. We will always be conscious of our choices and understand there may be consequences but we will not let tcomm get in our way.

 

Tony

[WRHT379]

4 hours ago, kidphc said:

If we are discussing simulcast, and lora back bones/ radio.

Why is the group not talking to the local pd. Who probably has simulcast already set up. Old gear that can be repurposed, get potential federal grants and be administered ( really only sounds like you need 1-2 tac groups). As well as the license for the extra frequencies. Probably can be encrypted as well.

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Yes, you are in my head. We all now gmrs will probably end up in the trash heap because of all the repeaters and cross talk making it unusable. So solutions for when that happens it what LoRa and other avenues are for. Keeping an open mind on solution that can make this work. We are trying to create a redundant and super resilient system for community members to communicate with each other as well as create a direct line from agency support to the community.  We all know people are busy and we have to minimize the impact this may have on their lives so we try to make it approachable. Gmrs is easy to license and allows the use of repeaters. Pretty cool . Of course we have blended amateur(ACS) ,ARES , smoke signals and everything else into the mix to accommodate each community and their way of wanting g to do things.  We are here to try and minimize the gmrs jamb up or frequency overlap from other repeaters and users. So we have thought of securing a couple frequencies for this and some how making it license free or easy to get for the public. I will eventually sit down with the FCC and discuss. They have reached out and asked us for solutions to Tubbs, Maui etc.

 

Tony

[kidphc]

Yes, you are in my head. We all now gmrs will probably end up in the trash heap because of all the repeaters and cross talk making it unusable. So solutions for when that happens it what LoRa and other avenues are for. Keeping an open mind on solution that can make this work. We are trying to create a redundant and super resilient system for community members to communicate with each other as well as create a direct line from agency support to the community.  We all know people are busy and we have to minimize the impact this may have on their lives so we try to make it approachable. Gmrs is easy to license and allows the use of repeaters. Pretty cool . Of course we have blended amateur(ACS) ,ARES , smoke signals and everything else into the mix to accommodate each community and their way of wanting g to do things.  We are here to try and minimize the gmrs jamb up or frequency overlap from other repeaters and users. So we have thought of securing a couple frequencies for this and some how making it license free or easy to get for the public. I will eventually sit down with the FCC and discuss. They have reached out and asked us for solutions to Tubbs, Maui etc.
 
Tony

Around here (montgomery county maryland). Local municipality set up the radio system properly. Public service network on 800mhz. They could of gone with lesser equipment and use higher gain antenna. But chose to go with a mandate that required 98% coverage of the county with an ht. Yes this included in people's basements and in parking garages.

What they needed up with was a 2 site simulcast system. It is one of the best systems in the country. I have used the harris xg100m and a g5 unification in some absurd locations with the ability to listen to the county radios.

Either case, the state police use part of this system as well as many other agencies. Each pretty much has their own main talkgroup and tac channels. This includes the cert (was react) teams.

But it took a lot of handshakes and negotiating from multiple people to get it the way it is. But as a public safety group you might be able to get the local council, pd, fd and ems onboard to get you some talkgroups and interop group channels. Hell they probably have some old xts2.5/3k/5k. Hell 700/800 Mhz Motorola gear are dirt cheap compared to the vhf/uhf r1 counter pars. Think like $60-80 vs 200-500 for a unit.

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[gortex2]

Simulcast and Linked are 2 different things. The SLR is made for linking in DMR not analog. Simulcast would be all transmitters and receivers on the same channel basically not destroying the other frequencies so others can use them. Linking in a close are ties up multiple channels.

For SAR I use Quantars and MLC8000 convertors. You need GPS timing for both boxes but it works very good. Its not cheap to do simulcast correctly. The other thing you may look at is voting first. You may have enough TX coverage but voting receivers would help HT's get into the repeater. My GMRS sites are setup with this. Your SLR can be used for that again with a MLC or other "voter" box. Much cheaper to drop receivers around vs TX stuff. 

[WRHT379]

1 hour ago, kidphc said:

Around here (montgomery county maryland). Local municipality set up the radio system properly. Public service network on 800mhz. They could of gone with lesser equipment and use higher gain antenna. But chose to go with a mandate that required 98% coverage of the county with an ht. Yes this included in people's basements and in parking garages.

What they needed up with was a 2 site simulcast system. It is one of the best systems in the country. I have used the harris xg100m and a g5 unification in some absurd locations with the ability to listen to the county radios.

Either case, the state police use part of this system as well as many other agencies. Each pretty much has their own main talkgroup and tac channels. This includes the cert (was react) teams.

But it took a lot of handshakes and negotiating from multiple people to get it the way it is. But as a public safety group you might be able to get the local council, pd, fd and ems onboard to get you some talkgroups and interop group channels. Hell they probably have some old xts2.5/3k/5k. Hell 700/800 Mhz Motorola gear are dirt cheap compared to the vhf/uhf r1 counter pars. Think like $60-80 vs 200-500 for a unit.

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Ok. This sounds like the commorodory I am talking about unfortunately our agencies all are send alone and keep everything close to the chest. One really doesn't want to help the other. This is the first time in a long  time to see departments starting to talk and want a better system. It could happen and we are considering such a thing each step we take. We are not a selfish group. We want unity. We have to put egos aside. And achieve the awesomeness you folks have. I would like to hear me about your setup.

 

Tony

[kidphc]

Unfortunately, most government radio admins want to play God.

I wonder if it was the county council that enforced the requirement or each depth voiced they wanted that requirement added.

Either case, it's the people that won. On the next county over I often hit dead spots with their system.

It's funny to see in other counties every one running multiple high gain antennas. Where in moco almost all the vehicles are running low gain antennas, minus the few exceptions.

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[WRHT379]

54 minutes ago, gortex2 said:

Simulcast and Linked are 2 different things. The SLR is made for linking in DMR not analog. Simulcast would be all transmitters and receivers on the same channel basically not destroying the other frequencies so others can use them. Linking in a close are ties up multiple channels.

For SAR I use Quantars and MLC8000 convertors. You need GPS timing for both boxes but it works very good. Its not cheap to do simulcast correctly. The other thing you may look at is voting first. You may have enough TX coverage but voting receivers would help HT's get into the repeater. My GMRS sites are setup with this. Your SLR can be used for that again with a MLC or other "voter" box. Much cheaper to drop receivers around vs TX stuff. 

I think you understand what we are trying to do. It would be a link and simulcast combo. Receives sites for HT's, simulcast to conserve frequency use and linking for big events where we would want to tLk across multiple districts. Thanks for your reply

 

Tony

[nokones]

According to the mygmrs.com map, all the GMRS channels are not overly used in Sonoma County. I just took a quick look and the "725" channel pair appears to be a good candidate for a county wide GMRS channel. You will need to get a good simulcast system designer so you can start designing and identifying the transmitter sites. You just can't plunk down a simulcast transmitter on any site and have a good working system. It'll take careful planning. I know what it takes to plan a good working simulcast system in Sonoma County. I spent a lot of time and driven many miles in Sonoma County to get a simulcast system to work.

To save time and effort you should try to acquire the space and services for the remote sites and mirror the Sheriff's UHF Simulcast system.

Acquiring the remote site space and services is going to be your biggest problem if improvements are required.

The County should be receptive in providing services for renting mux channels for a fee of course on their Microwave System.

You will need to identify where you will be locating your system control equipment.

[kidphc]

No one has mentioned if gmrs is used. All the household users or non-related users will need to be licensed.

It will probably be better to get an lmr/commercial license.

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[nokones]

23 minutes ago, kidphc said:

No one has mentioned if gmrs is used. All the household users or non-related users will need to be licensed.

It will probably be better to get an lmr/commercial license.

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I totally agree. That way the system users can operate under the system license authority and don't have to worry about getting an individual license.

I have several Part 90 Business Radio Service frequency pairs licensed statewide in California and if I need to I will give permission and/or give up a pair for his system.

[kidphc]

I totally agree. That way the system users can operate under the system license authority and don't have to worry about getting an individual license.
I have several Part 90 Business Radio Service frequency pairs licensed statewide in California and if I need to I will give permission and/or give up a pair for his system.

That is mighty nice of you. I mean it's not like the cost to get a pair is super expensive.

But most administrators off the bat would of not offered or put secondary user stipulations even the if pair wasn't used. You know "in case".

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[WRHT379]

On 4/26/2024 at 8:05 AM, WRHT379 said:

Good day Fellow Enthusiasts,

  My name is Tony the Chief Radio officer for Sonoma County Neighborhood Auxillary Communication Service(non agency, volunteers). We have created a 20 plus repated system here using the Motorola SLR5700 series repeater. we have deployed 1000's of radios to neighborhoods and teach resilency and self preservation using GMRS/Amateur/Cup and string/smoke signals/bullhorns you name it we will try it,  to communicate. I understand that we have very few GMRS frequenciesto use and we want to be good stewards to our neighboring counties. So i want to simulcast to minimize power output and fequency usage. We also plan to install backbone and redundancy using ubiquitous and LoRa radio. i am asking you good people for advice,  reference material and/or experiences in how you have done this. Presently i am looking at using the RTCM thin client or a stand alone RPI. I know my way around a RPI enough to ge tmyself in trouble and would prefer a more plug n play approach. of course money is a big consideration since we are a volunteer group.

i apprecaite you folks for doing what you do providing that redundancyfor your communities

 

Tony Goodwin

Chief Radio Officer: Sonoma County Neighborhood Auxillary Communication Service

Sonoma County, CA.

I really appreciate the advice and willingness to help from you folks. My vision for Sonoma County is to be an effective means for comms when all else has failed and be a good steward to my neighbors(frequency usage wise). You have givin me a  lot of home work and I thank you. I will be in touch.

I have included a couple of web links to our partners. 

Tony Goodwin

CRO: Sonoma County Neighborhood Auxiliary Communication Service 707 494-7494 

 

https://storymaps.arcgis.com/stories/07c0de00fd9f48c183f8cb273aad0706

https://www.wiconduit.org/radio

 

[tweiss3]

Reading back through this, I'm not 100% sure you need "simulcast". Do you have significant overlapping coverage of multiple repeaters or do you just have a ton of coverage pockets without overlapping? If the second, you wouldn't need simulcast, just need some version of linking. If you do have overlapping coverage, you would need true simulcast with GPS sync and voting. The RTCM module is only part of the simulcast solution, but it does require IP links.

Another option is new hardware. I can't find a definite answer, but the NXR-1800e has simulcast capabilities baked in (its a license feature), and will permit IP or RF backhaul. Just remember, if you are doing RF backhaul, you must remain within GMRS frequencies, you cannot mix/match the RF link with ham or Part 90 frequencies.

[WRHT379]

10 minutes ago, tweiss3 said:

Reading back through this, I'm not 100% sure you need "simulcast". Do you have significant overlapping coverage of multiple repeaters or do you just have a ton of coverage pockets without overlapping? If the second, you wouldn't need simulcast, just need some version of linking. If you do have overlapping coverage, you would need true simulcast with GPS sync and voting. The RTCM module is only part of the simulcast solution, but it does require IP links.

Another option is new hardware. I can't find a definite answer, but the NXR-1800e has simulcast capabilities baked in (its a license feature), and will permit IP or RF backhaul. Just remember, if you are doing RF backhaul, you must remain within GMRS frequencies, you cannot mix/match the RF link with ham or Part 90 frequencies.

Thanks for the reply, so it has been a learning lesson. We have the mountainous and valley topography. The whole approach is simplex within neighborhoods and neighborhood leaders having access to repeaters, while all will be listening for informational purposes. At the same time if an individual was isolated from other simplex users they could use the repeater near them(here is the barn burner,  make it work with HT's). Moving forward. We have grouped communities and allocated frequency pairs to them. Some communities required multiple repeaters to provide coverage in their community because of terrain. So we mimicked calfires approach and have multiple repeaters on the same pair using different input ctcss. So for example we have 4 repeaters in our area , same frequency pair, same output crcss tone, different input ctcss tone.  This allows users to use a HT and connect to the nearby repeater and the repeater pushes out there transmission at 40 watts. So whole community  area can hear it . So long story short, we have anywhere from 1 repeater to 4 covering an area of 50-100 sq miles . We established a band plan for the county where no frequency pairs are recycled outside of each designated community. This is our attempt to minimize our foot print and our effect on adjacent counties. Also we have other people doing their own thing as well as businesses setting up Family Repeated systems. We are trying to make this work for all. So with a that said. I want to be able to simulcast across the communities that have multiple repeaters on the same frequency and link repeaters that are not( nets , emergencies).  I would also like to pick and choose linking/simulcasting any number of repeaters for any givin incident. As for the network(IP) connection  We will establish multiple backhauls at each site but the primary one will be our own using 5ghz ubiquitous radios . We will use cellular and internet gateways when ideal and free. Our routers can accommodate multiple WAN's. I am also hoping this will lead to less power output on the repeaters since similcast and links will mean one transmission will be heard across all or a selected few repeaters. The repeaters no longer eill have to "yell"  to be heard. Another thing is providing network Access points at locations where neighborhood leaders can connect to from ICP's and possibly residenances . This will provide the most worthy version of communication.  I have to run to work. Thanks for your input and i hope i explained myself well.

Tony Goodwin 

CRO: Sonoma County Neighborhood Auxiliary Communication Service 707 494-7494 

 

 

 

[tweiss3]

So there is significant overlap in "communities" that have more than 1 repeater. You may have to do some prioritization of which repeater is linked. You will not be able to link all "4" repeaters to the other systems, as they will clash and you won't hear anything. If you have to have each, lets call them cells, cell completely linked, you will need to simulcast that cell. You don't need to simulcast each area, as those without overlap will be able to operate as an independent repeater. 

You should be able to link all communities together, simulcast or not, without too much of an issue using an asterisk system like MyGMRS uses, just point it to your master "server". But it sounds like you will have issues in quite a few areas that will require a true simulcast operation, which is not inexpensive. 

[tweiss3]

I'll add, based on your current footprint and what you are trying to accomplish, you need to bring in a professional that can discuss specific sites and coverages. Your scenario and goals exceed "recommendations" available on a forum. You are now in a detailed design stage, and all of your moving parts need identified and you need to realistically look at cost per site to see if you are willing to spend the money to achieve your goal. From a 10,000 foot view, you appear to be at the go/no-go decision point between leave it alone and spend 6 figures to get started in your linked enterprise.