Cap Plus Multi Site (3 sites) in building issues

[Scatpack16]

Last Year we installed a new Cap plus multi-site system for a school district and it seems to be small problem after small problem since the install. They are running SLR 8000(4 per site) repeaters on UHF for the system and using XPR 3500e handhelds for the teachers and XPR 5550e mobiles for the buses. They have about 3 or 4 school buildings that can not hit the system when inside the building, but can hit it when they are right outside the building. We reached out to Motorola for BDA quotes but the cost is just too much right now. So I have been trying to find alternative options to get this signal into and out of the buildings (leaky coax, etc). Any ideas I can try would be greatly appreciated.

The other issue seems to be a roaming issue on the busses. Sometimes they hit the system and then sometimes they dont hit it even though they are in the same spot. I know part of the issue is going to be the issues with the coax and antennas (we have found some coaxes crimped out with pliers and producing high reflection), but it still seems like it may be a roaming issue as well. Thoughts?

 

[kayn1n32008]

The help you need is far beyond a hobby website.

First there is not nearly enough information to even attempt to figure out what your issues are, never mind come up with a solution. At a minimum, your sites are not meeting your coverage requirements.

You need a COMPETENT RF engineer to come in and root cause your issues and engineer a solution.

 

[MTS2000des]

What he said. The level of expertise and involvement requires on site work with competent engineering and technical folks, not a hobby site. It's like SPACE-X asking a model rocketry forum for help solving a jet propulsion problem. You need a local shop with the right tools and talent on site to diagnose and come up with a solution.

 

[buddrousa]

Cutting corners and something happens you could and most likely will be held accountable.
Sorry to tell you but you are going to have to do this correctly and not cut corners.

 

[jeepsandradios]

This is the issue with shops "engineering" a system for a customer. As said you need a real engineer to look at the entire system and build it out the proper way. Throwing repeaters on a building and handing out subscribers is not the right way anymore. Back in the day when you dropped a 100watt Micor at the bus garagre and maxtrac mobile in the bus was different than now.

Oh and you need a competant shop to install and maintain it after. Poor mobile installs doesn't help fix the issue, but mearly creates more headaches.

 

[ramal121]

we have found some coaxes crimped out with pliers and producing high reflection

And this is throwing out a big red flag to me.

 

[kayn1n32008]

And this is throwing out a big red flag to me.

Not really. Manufacturers will install antennas and feed lines as part of the build.

Back in 2001, I found a brand new bus with an improperly crimped connector AND an uncut VHF 1/2 wave. Replaced the feed and cut the antenna to used frequency.

 

[RFI-EMI-GUY]

Last Year we installed a new Cap plus multi-site system for a school district and it seems to be small problem after small problem since the install. They are running SLR 8000(4 per site) repeaters on UHF for the system and using XPR 3500e handhelds for the teachers and XPR 5550e mobiles for the buses. They have about 3 or 4 school buildings that can not hit the system when inside the building, but can hit it when they are right outside the building. We reached out to Motorola for BDA quotes but the cost is just too much right now. So I have been trying to find alternative options to get this signal into and out of the buildings (leaky coax, etc). Any ideas I can try would be greatly appreciated.

The other issue seems to be a roaming issue on the busses. Sometimes they hit the system and then sometimes they dont hit it even though they are in the same spot. I know part of the issue is going to be the issues with the coax and antennas (we have found some coaxes crimped out with pliers and producing high reflection), but it still seems like it may be a roaming issue as well. Thoughts?

Reading between the lines it sounds like you have a system that was designed for mobile coverage (buses), but barely performs that task for some reason, and customer now wants or expected, portable coverage inside the schools, yet have no repeaters placed either nearby or inside the schools to provide such in building coverage.

BDA's are expensive and very tricky to deploy and maintain. In fact maintaining them is a huge problem as the environment (other radio systems frequencies) creates a perpetual game of whack-a-mole. The applications for BDA's aka disguised as DAS by some vendors, are very site specific and becoming less desirable.

Assuming the myriad of problems affecting mobile/bus coverage are first worked out, a logical solution would be installing local, IP connected, MotoTrbo repeaters for those schools that desire but do not obtain, in building coverage. The multi-site system infrastructure would need to accommodate those IP connected repeater resources and the mobiles and portables would need to be capable of roaming to those new repeaters. None of this will come cheap. The solution must be engineered to provide a desired level of coverage. If the engineer does not speak both TSB-88D and MotoTurbo, find one who does.

 

[ElroyJetson]

In my experience in years past, reliable and comprehensive in-building coverage, even on a UHF system, for a multi-story building complex in particular, becomes almost impossible without very carefully engineered BDA systems as part of the engineering answer to the problem. Leaky coax and distributed antenna systems may also be part of the answer.

There's just no way around this: It's going to take professional engineering and lots of money. Accept it. You won't be able to do this on a tight budget.

The school district is going to have to decide what level of coverage they will pay for. The more coverage, the bigger the bill will be.

I came to believe that good BDA system design is a black art that involves burning candles at midnight and sacrificing a chicken. It's not a disicipline I've ever made any effort to learn.