TRBO Issue

[adamsdwa]

We have a single site TRBO Cap + system that worked fine on prior 8300 repeaters. We upgraded to 8400's after several untimely fails due to the infamous 8300 problems. We reprogrammed the repeaters exactly as before. The only real difference is now they are part of a larger single site system and reside in 3 racks comprised of 2 cap+ repeaters used only for private 1 to 1 calls by management. The remainder of the racks consist of 12 analog 8400 repeaters. Everything is ran through tuned dbSpectra combiners and receive multicouplers. Power and link budget are identical for the digital and analog, maybe on slightly hot on the receive side.

My question is the person that installed them set the RSSI threshold to -124. I have read and agree that needs to be set higher. I changed it to -90. Subscriber units were also reprogrammed at the same time. We have been having trouble with areas the old repeaters used to work now no longer have coverage. If we get close to a door or window though, they work fine, and backing away from the door or window causes out of range to appear. Coverage from this site is on a 50 foot tower at 40 watts on a 6 db gain omni antenna with a 50 ft rad center on LMR-400UF with the proper connectors. ERP is about 22 watts and we are only trying to cover a 2 mile square area. DTF shows no faults and cables test well with SWR of >1 on all radios analog and digital.

Since the site test well, I started looking at the subscriber radio code plugs today. I notice they are also set to -124 for the RSSI Threshold. Have any of you gentlemen changed that on the subcriber radios as well? Any other suggestions you might recommend to get this system back working properly? Analog works great - only an issue with the cap+ side. If it helps we do work in a very difficult RF environment where the noise floor may reach -90 to -85 on a real busy weekend at some of the events we participate in. For that reason I have also thought of increasing the RSSI Threshold even higher, but do not want to blow away other nearby users or cause unneeded interference or noise to my other analog repeaters.

Thoughts? And thanks in advance for your thoughtful advice.

 

[Mars]

You self-diagnosed your own problem. The RSSI threshold is affecting your coverage. If it's set at a value like -124dBm, it will not repeat if the noise floor is greater than this value.

If there are nearby repeaters on your OUTPUT frequency, and you are trying to avoid causing harmful interference to the other repeater(s), take an RSSI sample of their site when it's transmitting, and measure the RSSI in -dBm using the feedline from the low side of your duplexer (transmit frequency). Use a TRBO radio in RSSI display mode, it's that easy. Then program this value +/- 5dBm into the repeater codeplug as the RSSI threshold.

If you want rule out the RSSI threshold issue, set the repeater and radios for -40dBm and see if there are issues. Using this strong of a value practically cancels out the threshold, and the repeater will work at all times.

Using a value like -124dBm is not wise. This value is so weak, even the noise floor at the average site will cause the repeater (or radio) to not transmit.

I set our RSSI at -120dBm and was wondering why the repeater wasn't working most of the time. Our noise floor was sitting around -112dBm. I added another passband cavity to the RX side of the duplexer and magically it worked fine! It also brought the noise floor down to -128dBm. So we gained sensitivity as well, as DMR works up to about -122dBm before it drops completely off.

 

[adamsdwa]

Seldom poster but frequent lurker. Mars your comments always seem to be valued by all, and you helped confirm my beliefs here. I've had a couple techs look at this over the last couple months. I started last week and will actually be in the field this weekend. As I went through everything and had the test performed I completely suspected this was the case. Based on your comments I've read on other post, I appreciate your comments and find them valuable in nearly all cases.

Thanks again. Other replies are still encouraged.

 

[com501]

If you don't have any one close to you on the same frequency, programming either the subscriber or the repeater to ANY low threshold is a recipe for disaster. This sounds like something a newbie would do. The default settings are NOT your friend in this case. If you are NOT worried about co-channel interference, the subscriber should be set for 'Color Code Free' and in call criteria should be set to 'Follow Admit Criteria'.

 

[nje431]

While everything said about RSSI settings is correct, maybe I'm missing something here. If I read what adamdwa said correctly, the problem occured with the replacement of repeaters. NO subsciber changes where made before the problem was evident. So subscriber RSSI values shouldn't be the root cause. Likewise, the problem was described as out of range, and I admit I'm not familar with the Cap+ ergonomics, but isn't that an indication of an outbound problem? If that's the case, the repeater RSSI settings would have no effect on outbound.

So I suspect something else is going on. The original post hit the obvious items. Might I ask if the 8300s were at firmware release 2.30.x or earlier, and the 8400s are at 2.40.x?

 

[com501]

The master UDP port must be unique to the Cap+ system. All peer repeaters must have a different UDP port for the local port address, but the MASTER UDP port address is the same across all repeaters. Any other repeaters that share the SAME physical network not matter the system type must have different UPD ports for each system.

The UDP port for the REST CHANNEL must be different from other UDP ports, and an IP address MUST BE assigned for the rest channel.

You need to download and dig into the System Planner for this new release as settings are QUITE different than what they were before.

Caveats:

MASTER repeaters must be equal or higher in Rev firmware than ALL other peers.
Systems with more than 2 revisions between all repeater and subscriber units in firmware are NOT recommend were the System Planner.
DO NOT duplicate UDP ports even on systems that seem separate, even if they are on different subnets using the same backbone. Bad things can happen.

 

[tmclucas]

Whoever set the repeater RSSI Threshold to -124dBm didn't know what that field was. The RSSI Threshold setting is solely for interference detection. If the repeater (or subscriber) sees non-MOTOTRBO carrier at or above that level, it will consider the channel busy. For a repeater, setting RSSI Threshold to a lower value than default of -100dBm runs the risk detecting site noise and placing the repeater into FCC Lockout or a "do not use" state. For Capacity Plus, the Rest Slot beacon will roll to another available repeater. The RSSI Threshold setting does not affect receive sensitivity.

Duplicating UDP ports isn't a huge problem, unless you're passing through firewalls or NAT routers. Firewalls and NAT routers sometimes have problems maintaining the correct sessions if they see duplicates. Sometimes they'll even change the port number when the packet passes through the network equipment. Repeaters will only accept traffic on the UDP port that it's been assigned in the codeplug. But in any case, using unique UDP ports is a safe mitigation strategy.

With newer firmware:
Make sure you now have set a Rest Slot/Site IP address. This IP address is the same on all repeaters in the Capacity Plus system.
Make sure you have the same Master IP Address in each of the repeaters. Using 0.0.0.0 is no longer acceptable in the Master codeplug.
Make sure you don't duplicate repeater RadioIDs with subscriber IDs or Talkgroup IDs. Putting repeater RadioIDs into the upper range of 65001, 65002, 65003, usually prevents this issue.
Use RDAC to check the Repeater Log for alarms that might cause the repeater to lower TX power, such as high VSWR.
Sweep the antenna and line at the site. Perhaps something was jiggled loose when the cables were changed out. (This is from experience of an N-connector falling off in my hand.)

If you're using MOTOTRBO 2.0 (XPR3000/XPR5000/XPR7000) radios with Capacity Plus, make sure they're using R02.40.02 firmware or greater.

 

[adamsdwa]

All - thanks for your replies. As it turns out the issue was clearly RF related. When I started troubleshooting I found that the repeater was -80 for the RSSI threshold which is correct for our RF environment. I could use the system fine within about 1000 feet. I could see the site yet could not talk even though in range. Upon further inspection, I found that our tech had done everything I had asked. While checking the "plumbing" I found the problem. Our freqs are 451.xxxx and 464.xxxx for transmit. Wouldn't you know that he had the combiners connected to the wrong repeaters. They are in two different racks (combiners that is), so I just reprogrammed each repeater and what do you know - everything works great!

Again thanks for your replies!