Repeater System Questions

[squirrel911]

Ok, first I am not sure where this belongs so please move if it is in the wrong forum.

So, I used to belong to a Volunteer Fire Department in Louisiana. That fire department had there own repeater along with the parish wide repeater. They had a setup that my current VFD would like to use. I tried to explain how the repeater system worked but I was told by 2 different radio shops they dont know how it was done so I come to all you experts and see if someone can help me out. I will try to explain it the best I can. so here i go.

Ok so there was a parish wide fire frequency that i will call Repeater 1. The FD i was on had our own frequency with repeater setup at our main station and I will call the Repeater 2. We all had kenwood portable radios. Channel 1 was set to Repeater 2 and channel 2 was set to Repeater 1. Now when someone called 911 the dispatchers would set off our fire tones on Repeater 1. When they did Repeater 2 would somehow hear this and open up a bridge between Repeater 2 and Repeater 1. I could hear the traffic on channel 1 of my radio. Someone would check in route in Repeater 2 and our dispatcher would hear it on Repeater 1. 90 secs after the tones went off the bridge between Repeater 2 and Repeater 1 would close and anything we said over Repeater 2 would just be heard on the repeater. Now our chief, asst chief, and 2 of our engines had mobiles with DTMF mics in there and if we wanted we could input a DTMF code on Repeater 2 and reopen that bridge between the two Repeaters. We would have to re-input the DTMF cose to close the bridge again. Now when we had natural disasters liek hurricanes and if Repeater 1 went down we could open the bridge up and then when the dispatchers had to dispatch any FD in the parish it would use Repeater 2.

Ok I hope I explained that correctly. So I was wondering a few things about this setup.

1) Has anyone ever used a system like this?

2) Is there a repeater system already built by Motorola, Kenwood, or any other company? and If so whats the price?

3) If not sold how hard would it be to build something like this?

Now I know my FD will have to get our own Frequency and we are already in the process of doing this. Also we are UHF here if that matters any.

Thanks ahead of time for the help.

 

[KK4ELO]

Your talking about SEVERAL thousands (if not tens of thousands) of dollars, if you could find a radio shop around here that could do it. Hickerson and Hillsboro use chelstorp in tullahoma for there channels, but it doesnt do what you want.

 

[squirrel911]

Your talking about SEVERAL thousands (if not tens of thousands) of dollars, if you could find a radio shop around here that could do it. Hickerson and Hillsboro use chelstorp in tullahoma for there channels, but it doesnt do what you want.

I understand that Hickerson and Hillsboro use Communication Specialist in Tullahoma and I already have talked to them. They have no clue how this system even works. Middle Tennessee Two-Way says it sounds like a Amateur Radio kinda setup. Now I did talk to my old fire chief in Louisiana today and he told me the guy that built there repeater for them only charged $500 for it. Now they already had a tower up so I know that will be a cost we will have to pay also. I asked him for the guys number so I can ask him how he did it and all. He is suppose to get back with me.

 

[KK4ELO]

remember another problem you will have is that i doubt very seriously that the coffee county comms director will let that be patched with the public safety system either. the tower would also have to be coordinated by the fcc, as far as location, height, antenna height...etc. also bear in mind, that the repeater will have to be constantly maintained as you wouldnt want a failure during an emergency. sounds like an awful lot of wasted money for a channel not needed.

edit: this is why we are also allowed to use the mutual aid, d/a, and beechgrove systems if we need to.

 

[squirrel911]

remember another problem you will have is that i doubt very seriously that the coffee county comms director will let that be patched with the public safety system either. the tower would also have to be coordinated by the fcc, as far as location, height, antenna height...etc. also bear in mind, that the repeater will have to be constantly maintained as you wouldnt want a failure during an emergency. sounds like an awful lot of wasted money for a channel not needed.

edit: this is why we are also allowed to use the mutual aid, d/a, and beechgrove systems if we need to.

The whole deal with the director would have to be dealt with by chief. IDK about all that. and as far as the FCC we already got all the info on all that. And i was told by the shop in Tullahoma if we can get it done they would maintain it for us if needed.

And as far as a channel not needed the FD wants there own channel for operations and special events.

 

[krokus]

If the FD in questions wants their own repeater, for fireground and other non-dispatch usage, and it is not tied into the county's system, it is not the county's concern.

If you want the dispatches to be carried over the FD's repeater, that can be reasonably set up. (Use a pager, with a base unit, to trigger the transmitter, and couple the audio out from the pager into the repeater. You could have an issue with de-sense, unless work is put in to handling this problem. Another option would be running a dedicated line to the central dispatch, and have the audio from dispatch simulcast over the repeater.)

None of this is going to be inexpensive, so be sure you really have a good use for the system.

 

[squirrel911]

If the FD in questions wants their own repeater, for fireground and other non-dispatch usage, and it is not tied into the county's system, it is not the county's concern.

If you want the dispatches to be carried over the FD's repeater, that can be reasonably set up. (Use a pager, with a base unit, to trigger the transmitter, and couple the audio out from the pager into the repeater. You could have an issue with de-sense, unless work is put in to handling this problem. Another option would be running a dedicated line to the central dispatch, and have the audio from dispatch simulcast over the repeater.)

None of this is going to be inexpensive, so be sure you really have a good use for the system.

Would the county dispatch hear us check in route on our own freq at first

 

[krokus]

The way I was describing it, no. You would have to transmit on something that connects to the dispatcher. (I believe Repeater 2, in your description.)

Your repeater, let's call it Repeater 3, would only carry the outbound audio from dispatch, and anything that your people transmit. It would only be carried to your people. (The dispatcher would be either keyed up on only their dispatch frequency, which could be patched through to Repeater 3, via a pager; or the dispatcher would be keying up both their main frequency and Repeater 3, via a hard-line remote.)

Of those two, I would suggest the pager option, as it adds less hassle to the dispatcher, and then does not tie up the repeater with whatever the dispatcher has to say, after the tone-out.

 

[squirrel911]

Oh ok i understand. So once dispatched we would have to check in route on Dispatch channel then switch back to our channel?

 

[ffemt601]

You need a bridging repeater controller such as the NHRC-7 , but in your case you use it to connect to your repeater and a link radio. You can set the timeout and control it via DMTF.

If I remember correctly the last one we bought was around 300 bucks.

NHRC-7 Repeater Controller

 

[squirrel911]

Now thats excatly what I am looking for. How hard is that to install on a repeater?

 

[ffemt601]

Now thats excatly what I am looking for. How hard is that to install on a repeater?

Its not that difficult if you have done it before, but I have to say that the install guide is lacking. Are there any HAMs on your FD or perhaps a local group could lend a hand?

 

[squirrel911]

Its not that difficult if you have done it before, but I have to say that the install guide is lacking. Are there any HAMs on your FD or perhaps a local group could lend a hand?

We havent bought the repeater yet. One person brought up building our own repeater out of some radios we already got. I dont know about doing all that. That kinda scares me. I dont think we have any HAMs on our department right now. I am studying for my Tech right now and will be taking mine in Feb but IDK that much yet. I know the basics on installs and programing but not building.

 

[ffemt601]

We havent bought the repeater yet. One person brought up building our own repeater out of some radios we already got. I dont know about doing all that. That kinda scares me. I dont think we have any HAMs on our department right now. I am studying for my Tech right now and will be taking mine in Feb but IDK that much yet. I know the basics on installs and programing but not building.

Its okay to build a repeater for HAM radio functions, but repeaters for public safety should always be purchased and supported by a manufacture rep as lives are at stake.

 

[krokus]

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We havent bought the repeater yet. One person brought up building our own repeater out of some radios we already got. I dont know about doing all that. That kinda scares me. I dont think we have any HAMs on our department right now. I am studying for my Tech right now and will be taking mine in Feb but IDK that much yet. I know the basics on installs and programing but not building.

Do yourselves a favor, do not try to build a repeater, and talk to a sales rep for your favorite radio brand.

There are a number of details to be sorted out, including dispatch, response, fireground, reprogramming of two-ways, and possible reprogramming of alerting devices (pagers).

When going into this level of complication, it might be time to consider setting up a county-wide system.

 

[squirrel911]

Its okay to build a repeater for HAM radio functions, but repeaters for public safety should always be purchased and supported by a manufacture rep as lives are at stake.

I understand that sir. I thank we may go with Kenwood if I can find someone who can set this up like we want.

Wirelessly posted (BlackBerry8530/5.0.0.973 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/105)



Do yourselves a favor, do not try to build a repeater, and talk to a sales rep for your favorite radio brand.

There are a number of details to be sorted out, including dispatch, response, fireground, reprogramming of two-ways, and possible reprogramming of alerting devices (pagers).

When going into this level of complication, it might be time to consider setting up a county-wide system.

I think you missed something sir. We already have a county wide fire dispatch. What we want is a private channel for our volunteer fire department to use after we have been paged out. We would use it on fire ground and for non-emergency traffic. the programming of radios and pagers we already do in house so that isnt bad. All the pagers would stay the same anyways.

 

[KK4ELO]

the last time i checked communication evolutions had to do all of the public safety programming. and that was recently, as i had to have mine reprogrammed.

 

[jim202]

Before you get all wound around the axle on doing this, you have a bunch of homework to do to see if this is even possible. The first thing you need to do is see what sort of budget you have to work with. Radios just don't drop off the radio tree at harvest time. If your really looking at a repeater operation, your going to need the radio, a duplexer and a good antenna system.

If I bypass the radio and just talk about the duplexer, it doesn't matter if your talking the VHF (150 to 172 MHz) or UHF (450 to 512 MHz), the duplexer is going to cost you between $3000 and $5000. The antenna system for a decent antenna is going to run over $1500 just for the antenna. Then you have the coax cable that will run you in the order of $18 to $45 a foot, depending on the type of coax you get. Don't forget the cost of the coax connectors. These can run from $11 each to over $45 each depending on the type of coax you use. These costs are dealer cost, not end user costs. Do not use any LMR type coax in a repeater operation. You will end up with all sorts of noise problems with the repeater over time. The double shield of braided copper over the foil shield has been proven to be the cause of noise in repeater operation with this cable.

Don't forget that you need some sort of supporting structure for the antenna. This can be a tower, water tank or real tall building. Hopefully on a high piece of ground to provide good coverage. Can't even begin to come up with a price on the supporting structure. You have no idea what or where it will be. Just for a number to look at, Rohn 25 tower in 10 foot sections is going for about $120. Again this is dealer cost and not end user cost. Don't forget to add the labor to install all the different pieces.

Next is the hard part. You need to find the frequency coordinator to work with to obtain the 2 (need a pair) radio frequencies that is will take to run the repeater. The coordinator is going to charge you a fee for the work depending on how many frequencies they have to deal with. Have no idea what the going rate is on this, but I would expect to see something on the order of $200 per channel. Don't forget you need 2 frequencies for a repeater. Frequencies are hare to obtain these days. This may be the show stopper right from the gate on your project. Also bear in mind that you haven't provided any info on the frequencies the county is using. You can't be right next to the other frequencies and expect your repeater to work at the same time your trying to work with the county. It just isn't going to work.

Go do some homework on this. Your in for a rude trip if you don't. Don't want to burst your bubble, but radio systems are not just something you pull over to the side of the road and pull a couple of boxes out of your trunk and your good to go with.

Been in the public safety radio side of things for over 45 years now. Seen how hard it is to make a project come together. Have worked as a radio engineering consultant for 2 different companies along the way. Currently work for a company that makes radio interoperability gateways. Travel all over the country to 911 dispatch centers and different agencies. Have seen just about all the jury rigs that anyone can dream up over the years. Plant your feet on this one and let the seeds grow. Unless you walk into this with an open mind and plenty of funding, it won't work at the end of the road.

 

[squirrel911]

the last time i checked communication evolutions had to do all of the public safety programming. and that was recently, as i had to have mine reprogrammed.

Communication Evolutions only does some FDs in the counties. Others use Communication Specialist in Tullahoma.

 

[KK4ELO]

Im going to respectfully leave this thread and keep my knowledge to myself.