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  #1 (permalink)  
Old 11-13-2017, 11:04 PM
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Default Fire Dept. Repeater Build

Hi everyone,

I'm looking for a little sanity check and/or advice here. I am a volunteer fire fighter in a small valley in British Columbia, Canada and am looking at building a VHF repeater system. The reason for this is that the valley is very long and narrow and for some mind-boggling reason has 4 separate fire departments. Since we have mutual-aid agreements in place, we often end up responding together for many incidents.

Our current dispatch systems are radio/call-out based, and I am putting together a proposal for local government to build a common dispatch in the form of a VHF repeater station patched into a phone line. The valley is lined by mountains, and there is a site that has off-grid power already that is available for use (run by local not-for-profit internet company). This site is about 4000ft above sea level and service areas are more or less between sea level and 300ft elevation. The furthest area for service is about 7.5 miles from the proposed station.

I've done a quick line-of-sight analysis from the proposed repeater station to the fire departments and their service areas, and produced a basic map to visualize it. My request is for confirmation that the distances on the map in the line-of-sight areas will be easy to communicate between repeater station and handheld radios without issue. I don't have any gear picked out, so just assume some pretty basic stuff (open to suggestions). Sorry, the map distances are in metric Map link below.

https://drive.google.com/file/d/1MLC...w?usp=drivesdk

Thank you,
Andrew
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Old 11-14-2017, 10:43 AM
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Just a quick look at your map I would think the location and distances would work very well for both mobiles and portables. Maybe too good. At 4000 feet for the repeater I would suggest a down tilt antenna that would better blanket the valley and not squirt the signal out horizontal.

If you intend to co-locate with a wireless internet service then you can use their coverage area as a guide. VHF will at least be as good as that if not a whole lot better.
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Old 11-14-2017, 11:16 AM
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Default VHF repeater

ramal121 raised a good point about antenna pattern tilt....

You also need to look at these items, especially if this is a primary radio system..

1- Backup power for at least 24 hours ( or more, and/or a fall back to a lower power setting to extend battery life)

2- Access to site for maintenance (the system will have a problem eventually)

3- Commercial grade radios/antenna/coax/installation (mandatory).

These should be separate from the internet service stuff already on site

I'm sure others will add stuff....

$.02
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Old 11-14-2017, 12:02 PM
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Does the phone patch plan is actually as a call-in solution when dispatch need to page out everyone? It may be a good backup plan, but as I learnt the hard way in the public safety world, the less dependant you are from third parties the better it is.

We had a phone line failure in the past and back then we had no way to monitor it, and caused delays (fortunatly, no lawsuit). Since then, private microwave antennas network is the way to go. If possible, establish a private net on 4.9GHz (look it up, it's a public safety band allocaton in Canada). You will only need to interface your radio system over IP for the dispatch.

You will also be able to send and receive data in order to monitor your site, including temperature, battery voltage, phone line status, relay activation and IP cameras etc..

Backup solutions are always possible, ranging from a VPN with a nearby ISP if possible, data over 56k, voice over phone line as noted above or direct VHF links.

Just my 2cents
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Old 11-14-2017, 1:06 PM
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I would avoid the phone line if at all possible. Who is your dispatch centre? How are the 4 departments currently paged our? You say radio/call out, how is the radio page out currently done? How are the current repeaters Ties back to your dispatch?


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Old 11-14-2017, 2:18 PM
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First, thanks for the responses. I have a lot more to think about now =)

To provide further background:

We do not have a dispatch centre. We are located about 300 miles from the nearest city on the BC coast. Our phone and internet primarily arrive via a single fibre-optics/microwave relay. We regularly have our connection to the outside world severed (except via satellite), possibly 2-3 times a year due to weather or accidents. Our local land-line numbers are still able to call each other, so we have stayed with a phone-patch (interconnect I think it's also called) so that we are not reliant on an outside solution.

That said, each fire department has it's own system. Two (including mine), have the interconnect system where all the members carrying their radios will hear the call, with a fan-out style text/cell call backup. Our department relies on members answering the calls as we do not have enough volunteers to have a dedicated dispatch person at all times. Our nearest adjacent department has a dedicated dispatch person, but is not always able to be in radio range... the other two departments have much worse systems. I think one employs a method whereby the landlines ring in a half dozen house holds and they do a fan-out style call-out. Needless to say, anything would be better than what we have, and this repeater was my solution to share resources for dispatchers and have a faster mutual aid response time.

For my department, the interconnect is located at the fire hall, and I was hoping to use this same interconnect on the new repeater's channel.

Addressing a few other points:

- Backup power should be sufficient. The ISP power requirements are currently something like 60 watts and the battery bank will last about two weeks from full, or so I'm told. They have ample solar (something like 8x300W solar panels, 2x marine wind turbine, and a large-ish diesel genset backup.). I'll look into another, smaller backup bank dedicated to the repeater.

-The ISP uses Ubiquiti 2.4 and 5.8ghz gear on site, with mostly directional antennas. If their coverage area is indicator to what I can expect with the VHF, then I think we're definitely good. Tilted antenna taken under advisement!

-Site maintenance should be good. Internet folks go up there semi-regularly, there is a helicopter company that operates year-round in the valley, and as a far-flung backup, there is a decent (albeit treacherous in the winter) hiking trail.

-I'm hoping site monitoring with IP or similar will be available from the ISP. They already have IP cams up there, with semi-public access. I will be able to assign local IPs to monitoring gear. I will have to look into the 4.9ghz band to see how I could possibly work it into this solution, but currently I'm not sure how we'd deal with a local phone line failure.

Again, thanks for the input guys. This is exactly what I needed; to flesh out what I am actually dealing with here, and getting more input on what works/doesn't work. As you can probably tell, our current situation is pathetic, so I'm trying to come in with the most comprehensive plan possible to convince local government and fire chiefs that this will be a major improvement.

One more quick direct question. If the VHF gear is co-located with the 2.4/5.8 ISP gear, will there be interference on either side? I have played with the possibility of erected a smaller tower nearby, at a distance that allows use of the ISP power/monitoring system, but doesn't interfere with their/our radio equipment.
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Old 11-14-2017, 3:32 PM
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The most important parts of the RF side are the antenna, duplexer and antenna cable, NO skimping there.....
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Old 11-14-2017, 6:12 PM
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If you are going to do this right, you will be spending 20-30k MINIMUM. There is no room for cutting corners here. Pay now or pay later. You donít want to pay later.

You need to bring a good communications company in.

Because you are off grid, you will likely want a Codan repeater, there is nothing better for off grid applications. Sinclair duplexer and antenna. 1/2Ē hard line if less than 100í from duplexer to antenna. 7/8Ē or larger if you have to go farther. Polyphaser as soon as the feedline enters the shelter. Tie everything into the site ground system.

Also expect to either provide your own power system, or pay to expand the site owners system.

You likely wonít have any interference issues with the WISP equipment. If you can share the same tower, do it. Save your self the headache of dealing with trying to get a Miscellaneous Land Lease(Alberta Term for a tower site lease on public/private land)what ever the BC Equivalent is. You likely will also need liability insurance payed to the site owner if your equipment causes damage.

As for a phone patch, a full duplex link to the valley bottom and have the interconnect at one of the halls. It will be easier(and much cheaper) than trying to get Telus to run a line up. You do not want to rely on the WISP for a VOIP connection.


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Old 11-14-2017, 7:30 PM
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With that much elevation difference its going to be very hard to get rf down into the valleys.
.
And gain antennas with downtilt will only compound the dead spots since electrical down tilt creates multiple pattern nulls.
.
I would consider using something like the Sinclair SC225M unity gain antenna.
.
With its 80 degree vertical beamwidth, it will be putting a rf pattern 40 degrees below the horizon without the nulls of electrical downtilt antennas.
.
Either way, an extensive site survey is in order to check for coverage and interference.
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Old 11-14-2017, 8:40 PM
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Okay, so I'm hearing that:

1) the elevation difference may be an issue instead of a benefit.

2) that there are significant costs, issues, and possibly paperwork associated with the off-grid mountaintop site.

Since the valley floor is more-or-less level (mild uphill as you travel east), would it be easier/better/cheaper to find a central location mid-valley to locate the repeater that would be on-grid (with backup power of course) and build a small tower instead of going mountaintop? The local government does own a piece of land with power running to it about mid-valley (just near the second-from-the-right fire department on the map).

Looking at the valley floor option would probably be easier to swallow for the gov't as well due to lower costs for install or maintenance. I may do another another quick line of sight map for a terrestrial tower and maybe experiment with different tower heights. Does this sound reasonable?

Thanks,
Andrew
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Old 11-14-2017, 10:01 PM
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Quote:
Originally Posted by nuclearguru View Post
Okay, so I'm hearing that:



1) the elevation difference may be an issue instead of a benefit.



2) that there are significant costs, issues, and possibly paperwork associated with the off-grid mountaintop site.



Since the valley floor is more-or-less level (mild uphill as you travel east), would it be easier/better/cheaper to find a central location mid-valley to locate the repeater that would be on-grid (with backup power of course) and build a small tower instead of going mountaintop? The local government does own a piece of land with power running to it about mid-valley (just near the second-from-the-right fire department on the map).



Looking at the valley floor option would probably be easier to swallow for the gov't as well due to lower costs for install or maintenance. I may do another another quick line of sight map for a terrestrial tower and maybe experiment with different tower heights. Does this sound reasonable?



Thanks,

Andrew

1) yes and no. There is no replacement for elevation. Usually. You are not needing coverage from Edmonton to Calgary, but you do need it for the +/-20km of your jurisdiction(s).

With the high site, you will not need a lot of power(good thing) likely you will be licensed at less that 15w ERP(Effective Radiated Power)

The antenna another poster suggested is a good choice. The 80 degree vertical beam width will cover you.

2) yes and no. It is an already existing site. You will need to deal with radio licensing, but not a land lease IF you donít put up a tower.

Putting up a tower in the bottom of the valley will add MINIMUM $10,000 to the cost. Depends what the minimum height will be to cover the area you need. Honestly, if you can get on the WISP tower do it. There is no substitute to elevation.

3) Something to consider is that if all 4 departments are always mutual aiding each other, being on a common repeater is likely a good thing.


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Old 11-14-2017, 10:03 PM
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Quote:
Originally Posted by nuclearguru View Post
I may do another another quick line of sight map for a terrestrial tower and maybe experiment with different tower heights. Does this sound reasonable?



Thanks,

Andrew

Really, unless you are using radio propagation modeling software, the LOS are not really worth a whole lot. You need to find someone who can do some coverage plots for different locations in your valley to come up with a workable plan for you.



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Old 11-14-2017, 10:51 PM
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What frequency pair will you use for the repeater? If the channels are too close together, the complexity and cost of the duplexer will soar.

Having a good duplexer, premium coaxial antenna cable and jumper cable and antenna are key to eliminating desense from the repeater. If you have desense, you will have NO repeater. Design the problem out from the start.

Grounding? What are you doing for grounding? Read Motorola R56.
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Old 11-15-2017, 6:39 PM
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Alright, thanks kayn1n32008. Might stick with the WISP setup and glean all the good ideas from this thread, including the antenna choice.

RFI-EMI-GUY, I haven't quite got that far yet, this was in the category of sanity check mostly. I'm told the WISP gear is very well grounded, without having an idea of what that means yet. I think I'm going to use the most valuable bit of advice I got in this thread and make sure there is a good installer taking care of these type of details. The info here will help me make sure we're getting what we want, and so I know some of the questions to be asking.

To wrap up, thanks everyone for your input; it has been immensely useful to me! When all's said and done, I may post back just to show it off and have you guys critique it

Just in case there's any interest, here's the site (pic in link below). It's beautiful up there!

https://photos.app.goo.gl/2UKAXqjsTOSzsC492

Thanks,
Andrew
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Old 11-15-2017, 11:07 PM
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Default Fire Dept. Repeater Build

Looks like many radio sites in BC/Yukon. The green commshell is a staple of the industry there. Never thought to throw a WISP in one though.

Codan repeater for sure, not only the best you can buy, it is the proper repeater for that environment. Budget 10-15K just for the repeater. Accept nothing less. Not much else is designed to operate in an un-heated shelter. Probably wonít even need more than the 9w exciter, you will get more than adequate coverage. Get a pair of frequencies at least 3MHz separation, Sinclair Duplexer and antenna, 1/2Ē hardline and make sure everything is well grounded. Also donít bother with a tower. You want to be inside that commshell.


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Last edited by kayn1n32008; 11-15-2017 at 11:32 PM..
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Old 11-15-2017, 11:12 PM
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Please update when things get moving. Let us know what equipment is going in etc.

Canít wait to hear.


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Old 11-15-2017, 11:27 PM
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WOW that is quite the view you have there. Do you get much wind?

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Old 11-15-2017, 11:34 PM
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Quote:
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WOW that is quite the view you have there. Do you get much wind?

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Iím sure they do. And lots of snow as well. Looks like thatís all pressure treated or cedar.

The gear in the sling and the platform the guys are standing on is a helipad. The commshell is below and further away.


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Old 11-15-2017, 11:47 PM
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Quote:
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Iím sure they do. And lots of snow as well. Looks like thatís all pressure treated or cedar.

The gear in the sling and the platform the guys are standing on is a helipad. The commshell is below and further away.


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The picture was confusing my perspective. I am sure the helipad platform is tied down well against uplift.

Quite a view!

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Old 11-15-2017, 11:54 PM
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Quote:
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The picture was confusing my perspective. I am sure the helipad platform is tied down well against uplift.

Quite a view!

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The picture was probably taken from a helicopter.

I figured out where this fellow is located. Since he has choosen to not disclose it, I wonít either. He really is in the middle of nowhere. Stunningly beautiful part of BC.


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