MOTO TRBO System Troubleshooting

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Jim1348
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MOTO TRBO System Troubleshooting

Post by Jim1348 »

I am just wondering if anybody can pass along any tips on how to help the radio shop we use troubleshoot our MOTO TRBO system problems. We have two UHF repeaters. Each is capable of two time slots. We, as end users, are using Motorola XPR6550 transceivers. I checked the menu/utilities and we are:

Firmware Version: R01.11.10

CP Version: 12.01.01

We did some testing in the daytime yesterday and found an in building dead zone. Outside of out building I could not find any problem areas. However, the midnight shift found an area outside of our building that they had trouble with coverage. They were getting "Bonked Out" as they like to call it. Anyway, I am just curious what sorts of things radio techs do to troubleshoot problems like this. Our frequencies are in the 406 to 420 mHz region. Are we using the most current Firmware and CP versions?

Also, for those familiar with MOTO TRBO, what are some of the msot common sources of problems with MOTOR TRBO equipment? Is intereference caused more often by other MOTOR TRBO users or non-MOTO TRBO users? Can nearby trunking system control channels cause probelms?

As a side note, probably like I lot of people here, I "cut my teeth" so to speak on old fashioned, analog narrow band FM equipment. I have some experience as an end user on a statewide P25 trunked system. I only have about 2 1/2 years experience as an end user with MOTO TRBO. It definitely isn't the same as the the analog gear I used over the years.
RRSM
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Re: MOTO TRBO System Troubleshooting

Post by RRSM »

I didn't realize "Narrow Band" equipment was "old fashioned"
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Bill_G
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Re: MOTO TRBO System Troubleshooting

Post by Bill_G »

With that kind of background, you should be able to do all the normal stuff. Check for desense. Check for co-channel users. Key one of the channels, and walk the property measuring RSSI on a portable. 5% BER is the 12db sinad of digital. If possible, listen to the system on an analog portable so you can hear local interference. ie: PC's and other equipment throwing off trash. You'll also be able to find multipath and fade zone in analog easier than digital.
Jim1348
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MOTO TRBO System Troubleshooting

Post by Jim1348 »

Bill,


That is interesting that you mention that. I was sort of wondering about the value of monitoring carrier squelch analog to see what pops up. Do you think that I should monitor both the input and the repeater output?


Jim
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Bill_G
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Re: MOTO TRBO System Troubleshooting

Post by Bill_G »

If you think there is a problem, sure. The earball is one of the best tools for troubleshooting.
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wavetar
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Re: MOTO TRBO System Troubleshooting

Post by wavetar »

It would be helpful to know the location of the repeaters/antennas in relation to the areas you have identified as problem areas. Are the repeaters in the same building, with roof mount antennas? What type of filtering is in use? What type of antennas? Are the two repeaters in the same location? Does everything combine into a single antenna? If on a common antenna (or co-located), do both repeaters give equal performance...ie: same problem areas for both? It may just be a plain old fashioned coverage issue, assuming the hardware checks out fine.
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Jim1348
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MOTO TRBO System Troubleshooting

Post by Jim1348 »

Good points. I will look into those things and see what I can find out. For whatever it is worth, since we have the two repeaters and people are trying to narrow down when issues happen, I am going to suggest that they grab a portable for the other repeater and see if it happens at the same time on both or just one of the repeaters.
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FMROB
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Re: MOTO TRBO System Troubleshooting

Post by FMROB »

Before you go crazy with RF testing, especially in digital you need to fully examine the programming of your portable radios. In DMR I have seen improper programming cause many system performance issues, and it is stuff that you can very easily miss. For example, how is channel access programmed in the radio, always, channel free, color code free. If they used channel free you may experience a lot more "bonk outs" than if you were to use color code free. Is someone using private call on your system, is it even one of your users. There are many, many people out there that "pirate" systems.

As far as coverage testing, here is a simple rule of thumb, specifically for in building coverage. Set up your repeater to run analog and a few portables on analog and walk around to do coverage testing. I will catch flack for this, but there is a higher than 90% probability that if you are working in analog that you will get digital coverage. We have done many NYC high rise building test where we have proved this true over and over. In fact there are many cases where you can barely even hold an analog repeater open during testing, to switch to digital and have coverage in those areas, which is the beauty of the digital technologies.

Now again, this is taking out any technical measurements, but sometimes it is just easier to test in analog to actually hear what the symptoms are. Just my two cents. - Rob
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Bill_G
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Re: MOTO TRBO System Troubleshooting

Post by Bill_G »

You're right Rob. Coverage is coverage is coverage. If it works in digital, but not in analog, then the system is already broken. It's nice that digital gives us that extra few virtual db of performance to fill some of the odd corners in a building that were poorly served previously. But, if someone is depending on digital to reach an important area, then they are in trouble.

One of the tricks I use when doing a building survey is my Radio Shack scanner. It has reasonable sensitivity, fair to poor selectivity, reliable squelch control, selectable attenuation, and a BNC antenna connector so I use any antenna I want. If it is at all possible, I inject 440hz, key the repeater, and walk the building with the scanner on my belt turned up just loud enough to feel the buzz of the 440hz without driving myself or other people mad with a constant tone. If I have to, especially in a high rent executive building, I use an earphone to listen to signal quality as I walk. I set the squelch for -90db, put the scanner on my belt to simulate how the customer uses their radios, and start my walk. If I can get -90db, then I can guarantee reciprocity meaning their portables can talk into the repeater with normal sensitivity in the range of -116db. I make note of all the areas the signal strength drops below -90db. Those are the places that need to be addressed. Up and down, back and forth, every hallway, every basement, every elevator, every mechanical level, every fire control closet, every parking level. It's good exercise, and it doesn't take long to map out a building or a campus with a simple pass/fail test. Then, it's just a matter of making sense of it, and coming up with a solution.

Because the scanner has horrible selectivity, it is easily swamped by local desense. There may be sufficient system RF in a specific area. Coverage should be good. But, because there is something operating right there throwing off hash, the area is unusable. A real portable with better rejection might mask it until you are very close to the source. Digital would certainly mask it. But, the analog scanner just has to be in the general area before it is affected even if the energy is broadbanded. Now you can break out the spec-an to look at the spectrum to locate the source of the interference. It is amazing how many EXIT signs, control panels, computers, printers, security badge detectors, cameras, microwave ovens, wi-fi access points, routers, network cable bundles, lighting, etc, have switching power supplies that trash the band for twenty feet in all directions. Article 15 goes right out the window. Get into a modern building where there are lots of these things, and you have crap piled on top of crap. It's a wonder any radio works at all.

If the scanner works, there is a real good chance your portables will work. If the scanner doesn't receive, then you know this is someplace you need to pay attention to. Or not. It might be impossible, or too expensive. Trbo might give you that extra little kick in the butt to work that one small place, but everyone knows that it is gravy, and not bank.
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FMROB
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Re: MOTO TRBO System Troubleshooting

Post by FMROB »

Bill, I agree 100%. I should have noted that we absolutely shouldn't rely on digital to fix coverage issues. It is nice however, in that tight corner of the 3rd sub basement to have the extra reach of the "perceived" digital signal. At NYC union prices, it is almost over $275.00 per hour for electricians to pull cable in some of these buildings, so it gets expensive, lol. Good tip on the scanner.

Rob
Last edited by FMROB on Sat Jun 22, 2013 2:21 pm, edited 1 time in total.
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Bill_G
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Re: MOTO TRBO System Troubleshooting

Post by Bill_G »

Electricians are expensive everywhere - even their low voltage guys. But, I've learned to not ruffle the building management feathers. If they have a preferred contractor, that's who I use. It makes life so much simpler.

A DAS is what most of these buildings need. A simple pull in two or three directions from a repeater through a splitter in a central location tends to work reasonably well. But, that central location most of the time is not central to the intended target area, and the pulls tend to be longer than the cable loss can support. It's a juggling act especially when there are multiple buildings involved like a detached parking structure, or a new wing on a hospital.

A scanner is a great addition to the toolbox. You can earball a problem before you break out the big guns to prove your point, and they are sensitive to noise that is below the threashold of most spec-analyzers. A scanner will help you ferret out that LCD display on the pump control panel that is two inches away from the SCADA transceiver when the panel door is closed. Open the door to work on the transceiver, and now everything works just fine. Close the door, and the link goes into COMM FAIL. It's a miracle.
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