Radio will not Rx unless close to repeater...Odd situation

[jcefd10]

We just accuired this frequency as the licence expired for the other and a neighboring county got it. But this is a very rural location. We seldom get much Inteference. I guess I'll wait till the new combiner gets put in and see what happens.

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[jcefd10]

Okay, I'll try what you suggested. I have been using both radios with the MON function, disabling the tones on the channel, and I do occasionally pick up something that sounds vaguely like a modem, only for a split second. We need we had a single problem with our old setup that was purely analog. It worked flawlessly

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[jcefd10]

This is what I hear short bursts of when monitoring the channel with only carrier squelch.

http://www.kb9ukd.com/digital/TRBO.mp3

 

[mmckenna]

OK, that makes sense. What I was hearing sounded like that, and there is another agency in your fine state that is running MotoTrbo on that frequency.

So, sounds like what is happening is that signal from the other agency is getting into your repeater.
There's a few ways you may be able to address this, but it's probably going to come down to professional help.
-looks like the frequency coordinator didn't do a very good job. Contact whoever assigned you that frequency and ask a polite version of WTF?
-Might need to check into the other agency and make sure they are running within specs. If they are operating outside what their license allows, then the frequency coordinator would't be at fault.

Seems like you guys sort of got the short end of the stick, but that's the risk of letting your license expire. Funny that a neighboring county would pounce on it like that.

This likely isn't going to be a simple fix. It's not a programming issue. You -might- be able to swap your TX/RX frequencies and make it work, but then you might end up interfering with the other agency.

The path is 105 miles, and there is some terrain in between, but I could be misreading it. 105 miles isn't out of the question

 

[mmckenna]

OK, belay my last....

I found your likely culprit:

WQPP657, Bellwood Volunteer Fire Department. Bellwood Alabama.
For some reason, they are running a 6 channel NXDN trunked system and one of those channels is your 159.450MHz.
300 watts ERP (!)
89 miles away. Again, there is some terrain involved, but it's possible.
The trunked system would explain the noise you are hearing. If they are using that as their control channel, then it's going to be a constant signal. If they rotate their control channels, then you'll get it occasionally.

Solution might be to get them to change their control channel, if that is the source of the issue, but expect some push back. If you get them to change their control channel to one of their other licensed frequencies, and -any- radio issue happens after that, including batteries discharging, someone not being able to talk to someone else, any silly little issues, and it'll get turned into "well, that never happened before we had to change our control channel". Seriously.

 

[mmckenna]

Why a volunteer fire department needs a 6 channel digital trunked system with 300 watts ERP is beyond me.
Maybe it makes sense based on their operations area and terrain, but it can be these overbuilt systems that cause issues even this far away.

If this is the issue, you may need to either find a new frequency coordinator who is paying better attention, or use the same guy and ask him to fix his error at his cost.
Wouldn't have taken much to go on site with a receiver and check the frequency first.

I'd err on the side of caution and just find a new frequency coordinator.

 

[jcefd10]

Thank you for finding that out for me!! But, would that be the cause of our radios not receiving beyond only a few miles? I heard the trunking sound twice this morning on my portable before I left home since I am using my MON option and not filtering the other traffic while there.

 

[cmdrwill]

In the video, the handheld is overloading the mobile radio receiver.

And as mentioned listen on the 'Repeater input' also.

 

[jcefd10]

The video was just for reference. It does the same thing on both mobile and portable, no matter how close or far apart they are

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[jcefd10]

I'm just wondering why everything worked fine until this new digital repeater was installed. Granted they did a major overhaul of everything, to be honest now, with everything new, it sucks. Bad.

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[riccom]

here is an idea, see if you can switch up the rx tx on the repeater, and see if that can help some.
i know it sounds crazy, but i think this could help out some!

 

[mmckenna]

I'm just wondering why everything worked fine until this new digital repeater was installed. Granted they did a major overhaul of everything, to be honest now, with everything new, it sucks. Bad.

Sent from my SAMSUNG S7.

Not sure what you had before or what the condition was.

If it was old antennas, coax, duplexers, repeaters, it could have been deaf enough that it just didn't hear it.

Could be the offending agency changed something.

The new equipment may just be better overall compared to the old equipment. If they put in a higher gain antenna, lower loss coax, better duplexer (or just better tuned), and a more sensitive repeater receiver, then it could be picking it up better.

Could be also something flaky. Tropospheric ducting can happen on these frequencies, but that's usually something that changes from day to day depending on weather.

Might be a good sign that everything is just working really well. In fact, one fix might be to put in a lower gain antenna....

 

[mmckenna]

here is an idea, see if you can switch up the rx tx on the repeater, and see if that can help some.
i know it sounds crazy, but i think this could help out some!

Yeah, that's a good idea, but it could create interference for the other agency. Since the FCC license calls out which frequency is the repeater input and which one is the output, that would be a change requiring a license update as well as maybe re-coordination of the frequency pair.
Wouldn't be a bad test, but would take the system down for a while, as every radio would need to be reprogrammed.

 

[mmckenna]

Thank you for finding that out for me!! But, would that be the cause of our radios not receiving beyond only a few miles? I heard the trunking sound twice this morning on my portable before I left home since I am using my MON option and not filtering the other traffic while there.

The other system is an NXDN trunked system. Since your mobile and portables are set to mixed mode, it's probably hearing the NXDN control channel and just staying with that. When you get closer to the repeater, the analog signal is stronger and is enough to capture the receiver better. I think..... Hard to tell when I'm on the opposite side of the country.

 

[jcefd10]

But, shouldn't the dang analog break squelch from 6 miles away? The Tx antenna is 150' on the tower. The old setup was 2 repeaters each w their own duplexer, and 2 antennas. I 1 for Law enforcement, one slightly lower for fire/ems.

They lowered the TX antenna 30', from about 175', installed the 3 new 50w repeaters, and a combiner. And everything went to crap

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[jcefd10]

911 just set the tones off ansni couldnt record it. As they were putting the call out, I pressed MON again and put the PL tones back in the channel... Signal stayed the same, voice disappeared. I toggled back and forth several times and it did as I've described at the beginning of the thread.

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[WA0CBW]

Your description sounds like they are stripping PL when they send out the paging tones. You said when you put the "tones" back in, don't you mean tone. PL would be only one tone.
BB

 

[mmckenna]

But, shouldn't the dang analog break squelch from 6 miles away? The Tx antenna is 150' on the tower. The old setup was 2 repeaters each w their own duplexer, and 2 antennas. I 1 for Law enforcement, one slightly lower for fire/ems.

They lowered the TX antenna 30', from about 175', installed the 3 new 50w repeaters, and a combiner. And everything went to crap

Sent from my SAMSUNG S7.

There's a lot of "maybe's" involved. Too many for me to answer from the other side of the country.

Some ideas, in general terms....
FM (even NXDN is using FM) works on a "capture" principal. If the receiver hears a strong enough signal, it'll tend to keep receiving that.

Antenna radiation patterns would play a lot into this. A high gain antenna on your repeater might be picking up the far off trunked system that's towards the horizon better than a 5 watt (or even 50 watt) radio low on the horizon.

Topography might be a big player. Hills have a lot of capability to impact radio coverage, and in ways that we may not like.

80 something miles isn't a lot for a strong VHF signal. If the path exist and both ends are using high gain antennas, you'll get a strong signal. The other agency is running a lot of power from a tower with probably pretty good antennas. You are on a hand held and a mobile running much less power from less efficient antennas and from a lower level.

There's a lot of testing that could be done to find the issue. An easy one for a tech would be to put a spectrum analyzer on your antenna and see just how strong the signal from Alabama is. You might be surprised.

I really think you're going to have to look at the overall picture, and probably change frequencies. I really think you need to talk to your radio shop and the frequency coordinator. Someone owes you and explanation. This should have been tested before turn over. The frequency coordinator should have caught this.

 

[jcefd10]

When i say I'm putting the tones back on my channel, means I'm turning MON off and swapping from carrier squelch to the DPL tones.

I also just noticed something else. Im monitoring the channel with carrier squelch only while at home. So it was the distorted sound on the video as the call came out. I then noticed every time the ems would key to respond to the 911 center, over the digital channel after the call came out, I heard that trunking sound come over the analog a split second before they began talking. Almost as if when they pressed the PTT it sent that baud sound, then keyed on the digital side....

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[KevinC]

In your video it definitely sounds like you are beating against another signal.

I agree on the co-channel interference.