Poor Repeater Coverage in a Valley and suggestions?

[rzq4x4]

We ( my local ambulance service ) are looking for some options on fixing a coverage problem we have in part of our service area. We have a Kenwood repeater ( don't know the model # off hand ) putting out 25 watts into a DB405 on top of our city hall about 75' in the air. The area in question is about 8 miles line of sight away from the repeater but it drops about 450 feet maybe more into this subdivision along a lake where we have no handheld and very limited mobile coverage. We need a way to get the signals out of the valley. Receive coverage in the valley is also poor. This became a safety issue the other day and we need to fix the problem. Thank god no one got hurt or died. Anyone have any ideas or suggestions. Cost is an issue but if the money needs to be spent then it needs to be spent. Thanks.

[rocketman]

Sounds like your ambulance company needs to add a satellite receiver somewhere in that valley area. That should help TX out of the valley.

[nmfire10]

Can the portables and mobiles hear the base? If so, then a well placed remote reciever and voting comparator would probably do the trick.

If the mobiles or portables can't even hear the base, then more drastic measures are needed. Either a higher transmitter and a remote reciever OR, a second complete site in the vallley somewhere that can transmit and recieve. You would then need to manually select which site to transmit on when using the base radio. You could of course you an automatic site selector but that gets complicated and even more expensive.....

[Susan157]

We Need To Ask A couple of Questions First.

Has AnyOne Tested The RF Watts Into The Antenna?
Has Anyone Swept The Antenna?
How Long Has The Repeater Been Operating?
What co-ax is feeding the antenna?
Has The Repeater Ever Worked Better Than
Now?What Is The Type Of Duplexer Or MultiCoupler
Used between The Repeater and the antenna?
What is the condition (Or spec's of Rx and Tx.)?

With The Basic Info You Should Get More
Info To See What Can Be Done To Help.


Many Systems Are Bought And Installed
"But They Were Not Commissioned"
Many Times It Cost Very Little
To Repair The Problem.

[RocketNJ]

With a repeater that has a HAAT of 75 ft (height above average terrain) to try and cover a 450 ft depression 8 miles away will be very tough, even if the antenna, transmission line, and duplexer are perfect.

As others have suggested you have a few choices, higher repeater location, remote receiver (if you cabn hear the repeater transmit, or second repeater.

George

[Nand]

Perhaps you could move the repeater in another tower near the top edge of the valley. With the proper antenna, you may be able to have coverage in both places depending on the total size of the area.
This will certainly keep the cost down because you will need another tower with any other option anyway and no additional new equipment is needed with the moving option.

Nand.

[/\/\y 2 cents]

How about increasing the output power of the repeater...getting your license in line w/ new output power, and then switching to a crossband PAC-RT system w/ higher powered mobiles 50 or 110 watt, 5/8 wave antennas and put your portables on 2 watts or so to give you much better battery life. It may be some $$ upfront to replace your hhelds and mobiles + vehicular repeaters, but think about how much it will cost for a leased telco line to the voters every month or for 2 ends of microwave. eventually the other way will end up costing more. I think this would be more cost effective chioce to this and at least you get a new radios in the process that you can put your hands on, instead of having the same old stuff that will need to be replaced anyways, or spending all the money for some stuff that sits in a tower site. What do you guys think?
Steve

[nmfire10]

How about increasing the output power of the repeater...getting your license in line w/ new output power, and then switching to a crossband PAC-RT system w/ higher powered mobiles 50 or 110 watt, 5/8 wave antennas and put your portables on 2 watts or so to give you much better battery life. It may be some $$ upfront to replace your hhelds and mobiles + vehicular repeaters, but think about how much it will cost for a leased telco line to the voters every month or for 2 ends of microwave. eventually the other way will end up costing more. I think this would be more cost effective chioce to this and at least you get a new radios in the process that you can put your hands on, instead of having the same old stuff that will need to be replaced anyways, or spending all the money for some stuff that sits in a tower site. What do you guys think?
Steve

No offense but I think that is putting a bandaid on a wound that needs stiches. And "A brand new radio in your hand" isn't a reason to do anything. If the portables they have now are fine, why should they buy all new ones?

"Some stuff sitting in a tower site"? Thats an interesting perspective.

[/\/\y 2 cents]

im not new handhelds and mobiles is the reason to do it saying it is a reason to do it....im saying if to upgrade the backbone w/the voters w/microwave or leased line...lets say it costs $87,000 + the monthly amount to link it all (if telco line is used) then 2 years later the subscriber/field equipment needs replacing at a cost or another $60,000 you just spent a total of 147,000$ on radio equipment in 3 years...1 to solve coverage, and 2 to get the crapped out hand helds and mobs replaced. Yes it fixed your coverage, but now you have to deal with another radio related expenditure 2 years later and you thought everything was fine and dandy in the radio department. Now, with what I am proposing is that 1, you solve your coverage problem in a upfront 1 time payment form of maybe 100,000$ (no possible monthly fees), and 2 you eliminate the chance of having to replace the other side of the system as well (the hand helds and mobiles) and you get the most out of the little budget you have for equipment. Good coverage isnt going to do you any good if now your radios are smashed up and not operating properly (you just go from one problem to another) I was only suggesting that it would be more cost effective when you roll everything up in to one transaction that wouldnt even require a revolving monthly payment. Thats all...the new radios was simply a way to look on the bright side of the whole thing since nobody likes forking over money. Kinda like a catalyst.
Steve

[/\/\y 2 cents]

changing the 1st line so I dont look like corky to: "im not saying getting new portables and mobiles is a reason to do it, im saying..."

[rzq4x4]

Any suggestions on what the antenna height should be. Moving the repeater is not really an option because it is centrally located and has good coverage everywhere else. The antenna height would be the easiest to adjust. Any body got a formula or good way to calculate the best possible height. Increasing output power is going to happen. We just need the receive once the power is increased.

Remote voting site has been considered. Any body have a suggestion as to what to use. We really don't want to pay for leased lines if we don't have to. Is there a way to link it wireless?

Thanks for all your suggestions.

John

[Nand]

Moving the repeater is not really an option because it is centrally located and has good coverage everywhere else. The antenna height would be the easiest to adjust.

What I was trying to say is that you will need a higher tower either way you go. In that case I suggest that you move it towards the edge of the area that has poor coverage and because of the increased height, you will not loose your old coverage.

Nand.

[RKG]

If I understand the problem, the rim of the topography just before the dip into the valley is acting as a "near field obstruction." Without knowing more about the specific topographic profile, I'd bet that it would cost a good deal more to increase the height of the City Hall tower sufficiently to get into the valley than it would to implement Nand's suggestion of locating the repeater closer to the rim.

[srefurd]

Hey maybe he can go to http://www.topozone.com and get the url and post it for us to see the topography.

[rzq4x4]

Here is the topozone map. the city to the north is where the repeater is located about the center of the city and the subdivision is located just nothe of Lake Como on the bottom of the map. Thanks, John

http://www.topozone.com/map.asp?z=16&n= ... ayer=DRG25

[nmfire10]

I like the idea of moving the repeater as well. Has the potential to do a few things:

1. If this will fix the coverage, no need to remote recievers

2. No need to for leased lines to connect you dispatch/station to the tower. You can use a low power control station and a yagi antenna on the roof.

3. No need to buy all new portable radios if there is nothing wrong with the ones you have.

4. Going along with #3, no need to buy over-priced crossband repeaters for every unit.


Look at what is in the area to put the antennas on. Existing towers, water towers, tall buildings, etc.

[RKG]

The "topozone" map printed illegible at my end, but I've done some quick investigation with Delorme Topo-USA:

The ground level in the center of Elkhorn, WI is about 1,040' MSL. The topography in the direction of Lake Como is relatively flat for about 4.75 miles, and then it drops 200' in less than 1/2 mile (2,450'), from the intersection of Highland Dr. & Ridge Road (1,029' MSL) to the intersection of Robin Road & N. Lake Shore Dr. (861' MSL).

Given this profile, it is hardly surprising not only that portables and mobiles in the subdivision can't get back to the City Hall repeater, but also that they would have trouble hearing the repeater.

If you draw a profile of this line, it appears that, in order to maintain an eyeshot from the center of Elkhorn to the latter intersection, you would need a tower rising to about 2,200' AGL (above ground level) at the center of town. This is obviously impractical.

If you wanted to move the repeater site, the best location appears to be on or near Geneva National Ave., N. A 50' tower at that location would cover both the subdivision the lake and a control station at City Hall, but you would probably need something on the order of 200' to preserve the coverage you have from City Hall in other sectors.

It is a common frustration that RF, regardless of power level, does not bore through dirt and rock.

[nmfire10]

If you draw a profile of this line, it appears that, in order to maintain an eyeshot from the center of Elkhorn to the latter intersection, you would need a tower rising to about 2,200' AGL (above ground level) at the center of town. This is obviously impractical.

Oh c'mon. Think of it this way. With a few miles of Christmas Lights strings on all the guy wires, it would be the world's largest downtown lighted christmas tree.

[RKG]

True. And might be accepted by FAA in lieu of regular tower lights. However, you might have to register as a potential satellite hazard, in addition to aircraft hazard.

Engineering issues with towers go up geometrically as tower height increases. I was once tangentially involved in construction of 900' tower. I can't imagine anyone engineering one 2,000' tall.

[nmfire10]

Isn't 2,000ft the tallest you are allowed to build anyway? And how much does the guy who has climb that thing get paid per hour?

[srefurd]

I don't THINK there is a legal restriction on height. I think it is a $$$ and engineering problem.

[commstar]

On the Topo map there is a "radio tower" site noted two grids to the left of the word Como. I do not have the ability to profile this area and am not familiar with it at all but perhaps looking into that facility might be worth- while as it might have all the infrastructure you need already on board. In my experience, sometimes the best/easiest answer does not always take the most direct route.

A public safety appeal to a local site owner might open some new doors for you- it has for me in the past. Also with this in mind perhaps looking at what your local water, power, county and state folks have available in the way of site both improved and unimproved would be a good thing to acquaint yourself with. How does fire and Law cover that area?

I am familiar with a College that lets the local Cable TV folks have rooftop space in return for Basic Cable TV for the entire college and allowing the cable company to flaunt the fact that they donate the service. Works for me. With that nice centrally located water tower there perhaps you have some thing to barter with.


Goodluck & Godspeed

FOR SALE: One slightly used soapbox

[Jim202]

As with most public safety comm systems, funds are always at the top of the list. As others have said before, it cost big bucks to put up tall towers. I have always found that looking around for existing structures save much of that thin line of funding.

If you mangae to locate something along the rim line of the drop off, pay attention to just what antenna you install. With trying to fill in a depression, it would probably take an antenna with down tilt. Problem is that you realy don't want the down tilt for the rest of your coverage area.

You may end up with a power splitter and 2 antennas. One with a down tilt into the depression and a 180 degree pattern or what it takes to cover that area. The other antenna would be probably a standard one that is directional back into the area covered by the city hall tower.

Your getting into some interesting RF engineering that will probably take some time playing on a computer model to determine just what you should end up with. This is not something that you just want to go out and try. The computer is much cheaper than a tower crew messing with antennas for several days. Then the drive testing to see if it works.

Think this one through before spending anything. It will pay for itself in a short time.

Jim

[motisking]

Add a second stand alone repeater on the same freq with a different input PL.
RPTR IN RPTR OUT PL IN PL OUT
EXAMPLE: F1 - 469.500 / 464.500 PL 123.0 / 123.0
EXAMPLE: F2 - 469.500 / 464.500 PL 88.5 / 123.0

Place the second repeater where coverage is needed and can be heard by dispatch.

P.S. AKA "Poorman's voting"

[W4WTF]

Add a second stand alone repeater on the same freq with a different input PL.
RPTR IN RPTR OUT PL IN PL OUT
EXAMPLE: F1 - 469.500 / 464.500 PL 123.0 / 123.0
EXAMPLE: F2 - 469.500 / 464.500 PL 88.5 / 123.0

Pace the second repeater where coverage is needed and can be heard by dispatch.

P.S. AKA "Poorman's voting"

Thats exactly what we use, works pretty well for us.

[007]

John-

What department are you with down there?

Send me the particluars of your system in a PM and I'll see what my collective RF geeks can come up with for you.