I need a crash course in radio tie lines/advanced repeaters.

mavericknet · Post by **mavericknet** » Sun Jul 14, 2002 4:29 pm

Ok, here's the situation. My town's public safety repeater (don't know what kind, how its set up, know its kept under lock and key by the contracted dealer) is shot. It's performance generally sucks, but when the thermo. breaches 87deg. it pitches a fit, and at 90 or greater would make a better anchor. The local dealer won't fix it anymore and is attempting to pitch a new "system". However, from what I heard the price is absurd. I have an out of state dealer who has come to me with a very reasonable price for an MTR2000, however, I need some special additives, I think.

Heres the set up that I don't understand, the town dispatch center at location "A" about ten or so miles from repeater is directly attached to the repeater. When a transmission is made to the repeater the center recieves on the inbound side only, when they transmit it goes directly out the outbound side. Without using the "repeat function". I know this probably sounds simple, but advance radio theory still illudes me... Educate me oh great ones.

2nd, I need to be able to set off QCII tones using DTMF, it already does it and I have a feeling they're just add on gizmos like I have at my ambulance headquarters.

3rd, I have a grasp of how radios works, but one question that plagues me: If a tower is outputting a PL, and all the radios recieving on that frequency have CSQ will that transmission be heard. I believe they will, but I have been told by the resident creepy radio guy that it doesn't work that way and that the CSQ wouldn't here the PL'd transmissions.

4th, and finally, can one repeater say an MTR 2000, repeat multiple frequencies from one unit. Like let say a high use publics safety frequency and a low use ambulance switch down.

I know I should probably just "bow out and let the pros handle it" but at the rate their going I'm going to be driving the string and can truck.

Thanks in advance.

Monty · Post by **Monty** » Sun Jul 14, 2002 5:25 pm

Hi:

In short, you would be well off in the long
run to find a trustworthy Dealer. I know of
one in LIC if you are interested.

Not cheap, but they have always been
reasonable as far back as I remember.

Also, when it comes to [ Wire Line ] or
some other [ Remote Control ] of your
radio, it truly requires some specialized
work to get all the Audio levels and SP
functions as desired.

So, unless you are very savvy in the Arts
of Two-Way, I would either hire a unbiased
Communications Consultant, and take his / her
advice.

Most Systems have done away with wire line
control ( as it is expensive on a month to month )
Basis, and now use Special Link radios to replace
the Wire Line controls.

Anyhow, email me direct @ msisco9939@aol.com
and I will pass on the name of someone I know
in your area.

Monty

wa2zdy · Post by **wa2zdy** » Sun Jul 14, 2002 5:47 pm

Monty is correct. And since lives will depend on this system, having it done professionally is the only conscionable way to go. No offense.

As for the "creepy radio guy," he's an idiot. CSQ means the receiver will hear anything with a carrier - no matter what of if ANY PL tone. Obviously, the opposite is not true. A PL receiver will not hear anything unless it has the correct tone. If you are on a frequency shared by someone within radio range and you have a CSQ receiver, you are going to be annoyed very quickly.

Good luck and seriously, let them spend the money. It's not worth any shortcuts.

mavericknet · Post by **mavericknet** » Sun Jul 14, 2002 7:39 pm

Basically our town has said, too bad. Breaking 10K for a new repeater would be out of the question. Also, ditching a radio tie line would make me happy, and would work quite nicely for the ambulance comms, fire marshals, hazmat, etc, I was just trying to make the dispatch center happy. Half the problem is not knowing what the heck is running on site. I've been able to view the tower but I can't see the equipment. Our local dealer has the key for it because they're under contract (or so I've been told), and of the people I've talked to no one really knows who at the town (or police) are even responsible for the gear. Some people are also under the impression that radios are magical voo doo boxes that just work, and that there is a problem with everbody's radio, not the town tower. It's a mess, and yes... listening to connecticut public safety gets really, really, really annoying... especially when you hear them better than you hear your crews.

Post by **xmo** » Sun Jul 14, 2002 9:29 pm

"Some people are also under the impression that radios are magical voo doo boxes "

They are.

That's why the local dealer can't bring you into the inner-sanctum until you have been properly initiated and know the secret password.

Nand · Post by **Nand** » Sun Jul 14, 2002 9:30 pm

Jim202 · Post by **Jim202** » Mon Jul 15, 2002 10:12 am

Cut my teeth on a system like this many years ago. I would take a look at the duplexer before I go and spend much money on a new radio system. Check all the cables for tight connections.

Many of the older duplexers that public safety systems installed years ago need to be retuned over time. This problem shows up more when the temperature extreems come along. Mostly in hot weather. Have a local fire department repeater that just goes crazy when the room temp gets over 90. Found out the duplexer was in bad need of a retune. Did some magic with a couple of service monitors and it plays good. They also installed an air conditioner in the radio shack.

Still better to try and maintain a room temp that is more to the liking of electronics. Remember that the most often caused PA problem is high temps taking out the transistors. The cooler you keep the heat sink, the longer the radios PA stage last.

As for the telco lines, you have a normal 4 wire operation like Nand stated. Can't tell from you info given if it is a DC or tone control. There are not many DC radio control circuits left. Phone company wants the copper. Most today are tone controled.

As for the paging encoder, like Nand also said, the line levels are critical. You don't want to get the audio levels into compression. The encoder is at the dispatch position. Just push the buttons for what ever encode tones you want.

What I did years ago in a case like yours, was to put a small base station at the dispatch room and use it to control the repeater. Hooked up a cable so that if the console went out, all the dispatcher had top do was move the encoder from the normal console connection and plug it to the backup radio. This also allows you to keep right on trucking when the phone lines went away. Didn't have all the fancy control features as before, but could still dispatch just like the portables and mobiles use the repeater.

Jim

mavericknet · Post by **mavericknet** » Mon Jul 15, 2002 2:07 pm

This is a multi agency repeater, most of our QCII tone outs come direct from a zetron encoder. (cool) But some of our response units/command radios have DTMF pads that when the correct code is entered will trigger a QC tone out, from the tower for two depts. The dept. I represent has a little silver box strapped to the back of our "console" that does it. As for the wire-lines, they're already in place. I'm just trying understand what kind of new gizmos or gadgets would be needed on an MTR2000 to make the hook up.

The location is a cablevision sub/tower, looks like a decently ventilated building, but again I don't know the interior layout of the shack. And the tower is def. overloaded. I'd have to say at least 20 to 30 antenna of various bands and usage accross two interconnected 100' towers.

If the only thing wrong in the town (as far as radio comms) were the towers I'd say the tech just got shafted with some crap equipment that was bought on budget (which it was), but anything these guys touch turned to yick. They sit on HT's for at least two weeks and our "console" is four mobile radios hooked to marine batteries stapped into formica... the last Zetron model 5 we had, had a cable drilled through the bottom of a Maxtrac with it ends soldered to the radio. Suffice it to say the radio died a year ago and we replaced it with a CDM with the zetron hooked to the accessory plug.

We're in a bind here becuase most of our crew assembly and on scene command occurs through the town towers. Although truck to truck works great, it does require a truck with mobile radio. Most of our crew members have only HTs and Radius Ps.

Oh and about that radio guru I asked about the PLs, it was his daughter's graduation party, and it was about three hours in... so his mind wasn't quite what it ussually is.

Nand · Post by **Nand** » Mon Jul 15, 2002 4:42 pm

KitN1MCC · Post by **KitN1MCC** » Mon Jul 15, 2002 5:52 pm

i am up here in CT what freq do you hear us on and it depends were in Long Island u are i will be more than happy happy to lend a hand plus i have some locals guys who do real good work cheap/free

mavericknet · Post by **mavericknet** » Mon Jul 15, 2002 7:33 pm

For reasons of some anonymity left, lord knows you all know how to do FCC freq searches based on freq and general location I won't mention the actuall freq other than it's 45x.xxx, however if you live near Oneco, CT your fire department sounds really wonderful. Better than our fire marshals as far as clarity goes anyway.

Post by **vcaruso** » Mon Jul 15, 2002 8:19 pm

mavericknet,

I am in NJ but will be more than happy to give you a crash course on wire lines, etc.....

PM me or e-mail me directly and I will give you my #

V

Will · Post by **Will** » Mon Jul 15, 2002 9:48 pm

You deffinatly need a good engineer type tech. You do not find those at the local "dealers". I would be glad to look at your system, if you were within 200 miles.
I think there are several very good engineer types not too far away who would be glad to take a look, and you by the pizza.

Lets get a BatBoard team out there to help at least look closer into your problem(s).
BatBoard Team East?

Post by **Code3Response** » Mon Jul 15, 2002 10:24 pm

Will... where are you located? I have been contacted to be a consultant on our city's new 800 mhz radio ssytem.... think you may be a better candidate

Arent you in CA somewhere?

mavericknet · Post by **mavericknet** » Tue Jul 16, 2002 4:09 am

I think the only way I could look at the set up is by saying:

Here is a brand new system, for 1/2 the price, I need the key to the shack. That's probably the only way they'll find some lowly janitor who they gave the key to for safekeeping... or better yet they'll just call cable and get a new key.... oye.. if only politics weren't involved.

RadioSouth · Post by **RadioSouth** » Tue Jul 16, 2002 1:00 pm

I like that Will- To The Batmobile !

KitN1MCC · Post by **KitN1MCC** » Wed Jul 17, 2002 3:53 pm

i did not even know there was a oneco here in ct

mavericknet · Post by **mavericknet** » Wed Jul 17, 2002 7:17 pm

I pulled it off the FCC website, just where the tower is, it services some plainview, or plainway town... I think, I funny I remember the hamlet the tower sits in but I can't remember the name of the licensee.

tfr501 · Post by **tfr501** » Sat Jul 20, 2002 6:47 pm

Nand wrote: From your description, the system uses a 4-wire line, where the RX audio is routed to dispatch and back out again to the transmitter. This gives dispatch positive control and priority over the repeater.
Using a radio link instead of the phone lines can be cheaper in the end, but a lot more money initially if you need an additional antenna system for this as well. The cheap way would be for dispatch to simply use a local radio and work into the repeater like the mobiles do. But the phone lines are the preferred way to go. They are reliable and this is the way the emergency gets phoned in to start with. In our area, the province wide services are going back to wire-line or micro wave.

Nand.

Nand,
We have 4 wire lines on our system and every time a little storm comes through, we have problems with blown fuses which takes part of the system down. Due to this, they're considering radio link. Sounds like micro wave would be best to me. What's the cost and reliability of micro wave compared to radio link?

Thanks!

Nand · Post by **Nand** » Sat Jul 20, 2002 7:15 pm

RADIOMAN2002 · Post by **RADIOMAN2002** » Sat Jul 20, 2002 7:30 pm

Your first stop would be to Town Hall. If it is a cable TV tower they have to have a contract with the municipality for providing cable service for that area, and probably also a special use permit for the tower.(Freedom of information Act time) Then contact the tower owner who probably is the cable company, (I do know that there is a dealer out on Long Island that has most of the towers locked up for rental) Get access to your equipment, do an inventory to see if the equipment the dealer says is yours is 1) really there and it is what he says it is. 2) See what the radio room is like temperature wise. If the dealer cannot provide you with access if he is really truely the owner of the tower,and won't give you access. Go find another radio site. You could also go to the Town Fathers and say,(Why can't I see my own radio equipment) I have done some work at radio towers on Long Island before, PM me and I might be able to help, and if we both are talking about the same tower, you might be better off moving to another site. Maybe one of those high rise hotels along the LIE or Rt 110. And if you are a volunteer organization you might get in ther for free.

hfitzgerald · Post by **hfitzgerald** » Sun Jul 21, 2002 4:45 pm

Wired systems can be good, and they can be bad. They're usually reliable if new, but in our case, 20-30 year old wiring has caused some serious problems.
We've just finished upgrading the last of our wire-lines to 2-way digipeat radios in the Tornado/Severe Weather sirens. We had some LONG wireline runs for the old system, until about three years ago when a heavy rainstorm shorted half the network. The Tornado Sirens turned on at about 2 a.m. Sunday morning, and many of these were on top of public schools that are locked up on the weekends. Someone had to climb the towers and throw the manual disconnect on each one of the sirens (read: several hours). Monday morning the mayor had no problem approving the budget for a ma$$ive upgrade.

The local public safety network has been microwave for as long as I can remember. -but, the first T1 line went in last year to one of the newer towers. (kind of experimental) The tower was supposted to have a Microwave relay on it, but it turned out that a T1 was cheaper and would handle the traffic load. So far, no problems.

kb4mdz · Post by **kb4mdz** » Sun Jul 21, 2002 7:38 pm

Mavericknet -

Contact me off list and I can give you some pointers.

Chuk Gleason
kb4mdz@ipass.net

CHEFA2001 · Post by **CHEFA2001** » Sun Jul 21, 2002 10:22 pm

RADIOMAN2002, Are ya talking about Nopper's sites? Or A/T?, or??

If it's the site I think he's talking about, it's pretty messy.....

Well, as far as the "local" bat-team is concerned, I will volunteer to "check" it out, along with a friend who is very familliar with newer systems than I am, so we'd be able to steer him in the right direction....

Anyone else within the local area want to help out a fellow batwing member?

Anyone who is interested in metting up to check out his site, and or whatever else, PM me with details & for tel. # exchange. (of if we MUST, Nextel id exchanges. Seems to be the way to go these days.... Or we can use a local UHF machine, but I dont want to get my chops busted so, that would be only option for 3-4 at most and would be on a community rptr. off same tower (if it's one I think it is)

Ciao

mavericknet · Post by **mavericknet** » Mon Jul 22, 2002 10:38 am

Current set-up Two repeaters located on opposite sides of the town. Set up on two different channels but dump into the same frequency so the repeaters are cross town. Able to hit the repeater from a 25W mobile from most locations. However, they use two seperate inbound PLs to trigger the repeat. Is there anyway to set the repeaters to the same PL so there's one channel for the system. But only the closest repeater will trigger. I know there's got to be a way to do this, it's the premise behind cell phones. Your thoughts?

hfitzgerald · Post by **hfitzgerald** » Mon Jul 22, 2002 1:00 pm

Yes, use a voting receiver. Take as many receive sites as you want, link them to a central 'voting receiver' and it picks the receive site with the strongest signal. Most will switch between sites as signal strength increases/decreases and you won't be able to hear the transition. This is how some of our local Ham repeaters (and most of the public safety repeaters) work. Multiple receive sites, and one or more transmit sites. The voting cards do all the work...

CHEFA2001 · Post by **CHEFA2001** » Mon Jul 22, 2002 3:13 pm

mavericknet, wHAT do ya say?
Did ya want to meet up with a few of us and chat about your system, over a pizza, or lunch or whatever?

It woudl be alot easier than to go back and forth via pm, posts, and email, and also you would be able to ask questions till your heart is content as far as theory of operations and such.

If ya wanted to set somethign up, PM me.

Will · Post by **Will** » Mon Jul 22, 2002 10:15 pm

BatBoard Team East,, to the BatMobile.. Dont forget to load the "Port A Peter"!!
don't wory about the license I have a nation wide call on 464.6, .625 and .650 repeater/simplex.

I wish, seriously, that I could be there to help. But I am willing to head up Team West.

KG6EAQ · Post by **KG6EAQ** » Mon Jul 22, 2002 11:27 pm

So we gonna have some magnetic door signs made up? Something like "Batboard Emergency Response Team" or something similiar? Haha, we'd be the BERT team (Yes I know team repeats itself but it sounds cool!).

bernie · Post by **bernie** » Fri Jul 26, 2002 12:13 pm

My two bits worth;
Interesting challenge. Been there, done that.
I think that there is some one in the local government that "owns" this system.
I do not think that you shoud do anything other than discuss this issue at this time.
If you should manage to get into the site, and if you are discovered there, or if somthing should fall apart there is no telling how much fuss can be made. Legally you can't touch the equipment if it is under contract.
I have noted that some of these dealers techs have absoulutely no concept of site management, and are generally incomptent.
But they are very good politicians. You can bet that they know who owns the system. They are buddies.
The answer is that you must know the potilitcs of this County. You should do your home work and find out what two-way radio shop in your area is compitent. At one time there was Motorola, and every one else. Now there is every one else. There are lots of highly trained, and motivated people out there.
There is an awful lot more to engineering, installing and maintaing a radio system than is obvious to the causual observer.
"Nothing is simpler than some one else's job that you know nothing about."
Once you understand how things work, you will then understand how to approach the government with your proposal.
The issue is politics.
There was a question about a dual site multi PL access system. This is the most ecomomical design for wide area coverage. This system uses just two sites, and associated equipment.
The dis advantage is that if each repeater covers areas un accessible fron the other site, users can not talk from one area to the other. A user in the over lap area can use eather repeater, but could gert stepped on by a user on the other machine.
If there was one site that could be heard over the coverage area, several receiving sites feeding a Voting Comparator could be used to contol the
transmitter. The bits and peices to construct such a system can be costly, but this pales compaired to the problems associated with simulcast.
Here two or more sites transmit identical information on the same frequency. If there is a natural barrier such as a mountain, or great distance so that there is no overlap, it works quite well.
If there is overlap, ,the frequency offset between sites is held to very close tolerances, and the audio phasing is critical.
This means very high maintenance. There are many very clever solutions that can be applied to your individual situation, and it need not cost a fortune.
Aloha, Bernie