Repeater Solution Help Requested

[livitup311]

I'd appreciate any help I can get on this one...

Myself and a friend volunteer for a non-profit that needs a radio solution. We're both ham operators and Motorola "guys" in as much as we have bought Moto gear off eBay and programmed them for amateur use, as well as assisted with the upkeep of single-site amateur repeaters. We also both volunteer for an organization that has a radio need, and I'll admit, I'm not sure how best to support them.

The organization runs several summer camps around a central location. Each of the 5 camps is a somewhat self contained unit, but they all report up to the central organization, which is also on site. They need reliable radio communications, both within the camp, and with the central admin. They do have a LMR license, and are willing to amend it. Here are the requirements we've been able to figure out so far:

• Each camp needs discrete communications within the camp, to all staff members within that camp
• Each camp needs the ability to communicate with central admin
• Central admin needs the ability to communicate with each camp
• Radio communications should survive power, internet, and cell service outages, which happen more than once each camp season.

They currently use mostly Retevis H-777 radios, with UHF simplex frequencies for each camp, and a UHF repeater for connectivity to admin. The problems we are trying to solve are:

• The camps do not have camp-wide communications. Between the < 2 Watts of the 777s and the topography (very hilly), they can not reach from one end of camp to the other on simplex.
• Central admin needs a way to contact any camp, or all camps. Scanning between the camp channel and the admin channel is not optimal because the camps will pick up a lot of traffic they don't need to.

I was thinking a DMR solution would be reasonable, as each camp has high-speed internet service to their administration building, so a DMR solution with multiple repeaters, connected through the Internet would check all the boxes, except the requirement to survive power and internet outages. Backup power would be limited to batteries, which wouldn't be cost effective for day-long outages, which have happened. Unfortunately, there is no one spot on the property that every radio would be able to reach, so a single-site repeater doesn't seem like it would work.

We'd prefer to avoid going through a radio company to engineer this, as it would be cost prohibitive. We'd prefer to source components second-hand and build something ourselves. If this is an unrealistic pipe dream, I'm open to hearing that as well.

I appreciate any suggestions that anyone can give!

Edit: since this was moved out of the Motorola forum (fair enough) I’ll add we would prefer a Moto solution as that’s what we are most familiar with programming.

 

[otobmark]

probably look for some used Motorola xpr8300’s or xpr8400 DMR repeaters. Everything for IP connectivity is built in. One site should have a static IP address. If you could find a friendly C-Bridge owner you could route through that for sophisticated filtering of which talk groups go to which site/repeater and also eliminate your need for a static IP address.

 

[ramal121]

Nothing wrong with your ideas. It can be accomplished with DMR equipment fairly easily.
Now I will put the disclaimer that a radio shop (cuz I are one) can engineer something that meets your specifications and the safety valve that protects you is the fact that until the stuff is installed and you provide acceptance to said system, the checkbook can stay closed.

Now if you want to tackle this yourself have at it. It is not too complicated to put together. I have done this numerous times mostly with educational facilities that have wide spread campuses.

First off lets recap the requirements. 5 camps all with their own repeater to cover the entire camp. You'll also need a common repeater that is at the admin to tie this all together. Two channels, one being local repeat for just that camp and another that is an admin channel where all repeaters are connected together for admin/emergency purposes. Is that what you had in mind? Easy to do with the two DMR time slots.

If the camps need to be able to receive a call from admin then scan would have to be employed.

The stumbling block for me, anyways, is building a network to support all the repeaters. If you have internet you can build a tunnel through it to accomplish a VLAN. Be aware that if there is a power outage your ends may still be powered by backup but it depends on how robust your ISP is to keep itself going in cases like this. I like simple when it comes to these cases. In the past I have used products from DCB to build a VLAN with reasonable success. Find them here...

XT Encrypted Ethernet Tunnel Appliances

Encryption, Encrypted Tunnel, Encrypted Bridge, AES Tunnel, Encrypted Ethernet, Encrypted WAN, WAN Encryption, VPN, hardware VPN

www.dcbnet.com

As far as power back up, batteries or a UPS is the easiest way to go. A Motorola SLR 5700 repeater can be utilized for several hours to a day or more with a single 100 Ah battery depending on how much it's used. If that is not enough for you the extra batteries and a generator waiting in the wings would be a plus.

Most of my doings along this line have been with Kenwood gear, but Motorola can surely be used to do what you want. It's a very viable project.

 

[alcahuete]

Nobody says you have to use the internet for linking repeaters. You can use other radios, or something like Ubiquity network to make the network happen. All of that equipment and repeaters set up via battery backup.

 

[TampaTyron]

If already have internet at each location:
(not all call required)
-VPN between all sites with 1 subnet at each location that can see each other (all on same subnet or on their own subnet)
-6 site IPSC, with 1 repeater at each location preferrably in highest/central location for coverage (will need repeater/duplexer/coax/antenna/lightning arrestor- keep repeater firmware the same at each location, recommend 3-5dB gain antenna, stay away from hammy 9-11dB gain antennas)
-Slot 1 of system is wide area and goes to all locations
-Slot 2 is local to just that camp
There would need to be 1 radio monitoring the wide area channel at each camp. They would need to hear wide area comms and then move over to the local channel to relay info

(with ALL CALL capability)
-Same as above except with LCP instead of IPSC (IPSC free in repeater, LCP is approx $5k per repeater)
-Would need a unique IP subnet at each location for LCP
-I would wide area all of the talkgroups (6 locations and ALL CALL)
-Anybody could call anybody, chance of busying out a single repeater with 2 slots using 6 talkroups is low

I would run coverage maps of each location so you can see actual coverage.

Good luck! TT

 

[speedway_navigator]

Curious to see if anyone has done coverage studies of unity vs gain antennas in hilly terrain since gains tend to push more further out at the expense of an isotropic radiation pattern.

 

[speedway_navigator]

In the past I have used products from DCB to build a VLAN with reasonable success. Find them here...

Those look to be Mikrotik routers, the hEX series is current, I have a few of the old metal RB 133 and 532 models sitting in a cabinet.
Thanks for the link, because I dug under the old routers I found a laptop and table I forgot I had.

 

[JustinWHT]

I'll think this over when I have time, so I'll toss out only highlights.

To clarify isotropic, unity, and higher gain antennas. Isotropic antennas don't exist in the real world. Higher gain antennas have a flatter vertical beamwidth compared to a unity antenna, where the beamwidth is still sufficiently wide enough it won't impair anything. A 9 dBd UHF antenna mounted 1,500 above the average terrain still works for radios close in for a few miles out as well as 40 to 50 miles out.

In spite of me being the first WISP using UBNT (Ubiquiti) gear they lost my support over ten years ago due to terrible supply chain issues and wonky firmware updates. As I would often refer to their FW updates as: Add new features, fix bug of previous FW update, introduce a new bug."

They gave an iPod Nano engraved with Team Ubiquiti for Christmas. But after we parted ways, I posted - UBNT left me lumps of coal in my Christmas stocking, now they left me vaporware.

My tag line on the UBNT forum was: 'World's First UBNT airMax WISP" from 2009, when I was head beta field tester.

 

[TampaTyron]

We deal with extreme terrain in open pit mining and that terrain shifts every day. We use low power sites (5-10w at the TX antenna) and low gain antennas and high site density/lots of site overlap. Only newbs think high gain and high power equal good coverage areas in all instances. TT

 

[JustinWHT]

We deal with extreme terrain in open pit mining and that terrain shifts every day. We use low power sites (5-10w at the TX antenna) and low gain antennas and high site density/lots of site overlap. Only newbs think high gain and high power equal good coverage areas in all instances. TT

Your needs are certainly extreme and conventional thinking goes out the window.

Through I do agree the high gain and high power for repeaters has little if no advantage. Repeater output and mobile output should be reciprocal. A 100 Watt repeater with 9 dBd antenna will over-reach a 20 Watt mobile with 5 dBd antenna.

Unless the conversation goes like:
Base: Calling unit 2, I know your 100 miles away. Can you drive 80 miles closer to tower?
Unit 2 (three hours later): Unit 2 to base. Wassup?
Base: Are you about done with that job, we don't want you to hit overtime.

 

[speedway_navigator]

We used Canopy links when we started our WISP in southern Indiana, the U folks were not around then and Canopy is easier to spell.
I did some short hops with nano stations but that was before the firmware issues hit.

 

[JustinWHT]

I did some short hops with nano stations but that was before the firmware issues hit.

Did you visit the UBNT forum?

 

[kayn1n32008]

We deal with extreme terrain in open pit mining and that terrain shifts every day. We use low power sites (5-10w at the TX antenna) and low gain antennas and high site density/lots of site overlap. Only newbs think high gain and high power equal good coverage areas in all instances.

In BC, majority of the forest/natural resource radio system uses Codan stations, with out PA's. 4-7w TXPO. Links are usually less than 1w TXPO. It's a fantastic system, that has really good coverage in rugged terrain. Generally it's single element or two element folded dipoles for antennas, that are usually less than 4m AGL.

People really don't understand what can be done with minimal power, and proper design.

 

[DeoVindice]

We deal with extreme terrain in open pit mining and that terrain shifts every day. We use low power sites (5-10w at the TX antenna) and low gain antennas and high site density/lots of site overlap. Only newbs think high gain and high power equal good coverage areas in all instances. TT

Especially in some of the deeper pits. Too much gain without downtilt will do more harm than good.

 

[speedway_navigator]

Did you visit the UBNT forum?

Have not been working with the client in years but I did keep updates current while I was there.

 

[JustinWHT]

Have not been working with the client in years but I did keep updates current while I was there.

My last post was 12 years ago.

https://community.ui.com/questions/WHTs-Inspiration-and-Motivation/3fc1518a-a2ae-4eb8-9cfb-490a38b8a21f

 

[JustinWHT]

My last post was 12 years ago.

https://community.ui.com/questions/WHTs-Inspiration-and-Motivation/3fc1518a-a2ae-4eb8-9cfb-490a38b8a21f

My sig line was "World's First Ubiquiti airMax WISP".