Clicking on Transmission

Renamon · Post by **Renamon** » Thu Nov 27, 2014 8:53 pm

Random subscribers seems to have a constant clicking on the transmission, while others don't.

-> All users are handhelds (various makes/models).
-> Seems to go away with improved signal strength on users with the symptom.
-> Only noticed this since moving from PL to DPL.
-> Repeater tail does not have it.
-> P25 is fine.

Anyone have any ideas where I could start looking to track this down?

KG4LHQ · Post by **KG4LHQ** » Thu Nov 27, 2014 11:37 pm

Desense?

tsunami_australia · Post by **tsunami_australia** » Fri Nov 28, 2014 5:19 am

I noticed a similar thing with the old Philips (Simoco edition didn't have it for some reason) PRM804x series on receive where if the RSSI was turned on there would be clicking on receive. Turn RSSI off and the issue went away. May not be related but in-case???

RFguy · Post by **RFguy** » Fri Nov 28, 2014 8:06 am

Clicking on transmit, or on receive?

Renamon · Post by **Renamon** » Fri Nov 28, 2014 10:54 am

When subscriber A is transmitting through the repeater, other subscribers can hear a constant clicking on subscriber A's audio.

This is not present on simplex, and was not present (at least we never noticed it) before the repeater was re-tuned and moved to a DPL.

Renamon · Post by **Renamon** » Fri Nov 28, 2014 10:56 am

Clicking or a popping, about 5 times per second.

Renamon · Post by **Renamon** » Fri Nov 28, 2014 11:14 am

I uploaded a recording of it here: https://www.youtube.com/watch?v=usG7aUWKAt8

Will · Post by **Will** » Fri Nov 28, 2014 11:40 am

I have heard that same 'ticking' oh several PS repeaters before. But I have 'no clue' what is doing it. I had thought weak signal into the repeater.....

turtle9832 · Post by **turtle9832** » Fri Nov 28, 2014 11:44 am

I'm stuck on the, "random" part of the OP. Are there remote receivers? Or is it just a repeater station?

Also, can you elaborate on, "re-tune?" Was the station just switched from PL to DPL in the RSS?

What kind of station is it?

Renamon · Post by **Renamon** » Fri Nov 28, 2014 1:25 pm

-> Random: a couple XTS's (one is mine), a cheapy baofeng, a CDM1550 and a HT1250.
-> Repeater is a quantar on GMRS.
-> no remote receivers or anything, just the quantar at my house.

It was just aligned by me because of a hum/DPL issue here: http://batboard.batlabs.com/viewtopic.php?f=10&t=109856
After doing the transmit modulation adjustment, it is working great. Deviation and power were spot on to begin with. I never used a DPL on it before because of the modulation being so far off radios would not un-mute to the DPL it was sending.

When the repeater transmits its tail, an ID, transmit using a mic on the front of the machine or if you are really close to the repeater, there is no clicking.

Weird. I am thinking about changing it to a PL to see if the issue goes away.

-Jake

turtle9832 · Post by **turtle9832** » Fri Nov 28, 2014 3:33 pm

My apologies, when you referred to subscribers and signal strength, I was thinking in another direction. I also didn't see the other topic.

Post by **escomm** » Fri Nov 28, 2014 10:45 pm

This happens with all transmitting subscribers or just the one??

The Pager Geek · Post by **The Pager Geek** » Sat Nov 29, 2014 6:49 am

[EDIT: Missed that it doesn't happen with PL? Only happens with just DPL? If yes, disregard below...]

It's pointing towards a Receiver issue. Since it's weak-signal based (happens to radios far away) it's a small signal, it could be coming from anywhere.

Any chance you have a WiFi access point near the repeater or it's antenna?

I would suggest ruling out anything electronic around the repeater first. Have the person far away transmit for as long as possible to duplicate the problem. Literally start unplugging any electronics (I have a hunch it's wifi based on the frequency of popping) until it goes away.

Good luck on the hunt...

tpg

Renamon · Post by **Renamon** » Sat Nov 29, 2014 2:06 pm

escomm wrote:This happens with all transmitting subscribers or just the one??

It seems to happen when any unit transmits that it not right on top of the machine.

turtle9832 · Post by **turtle9832** » Sat Nov 29, 2014 2:17 pm

If the symptom goes away when the radio is that close, I think it may be important for you to tell us about the antenna, cabling, duplexer (if there is one).

545 · Post by **545** » Sun Nov 30, 2014 4:13 am

Many years ago, I had the same problem (I think) with a Uniden repeater. Motorola radios had no problems using it, but, we also had Midland radios, and if any of the Midland radios transmitted into the repeater, a clicking noise was heard. There were no other stations in the near area that used that frequency, so we turned off the DPL on the receive side of the repeater, and the clicking noise went away.

KE7JFF · Post by **KE7JFF** » Sun Nov 30, 2014 7:45 am

I remember ran into this once with a very very awfully built ham repeater that some genius decided to add DPL support with a tone board. While helping out the ham who built this contraption fix this (I wish had a picture...), we found that certain DPL codes didn't have it on. If you can, try using a different DPL code.

Renamon · Post by **Renamon** » Sun Nov 30, 2014 10:54 am

Switched from DPL to Pl.
Unplugged all wifi/other radios.
Symptom still remains.

Antenna is a rfs 201-7n. Duplexer is the 6 cavity rack mount celwave one that is an option when you order the quantar. Cable is ldf4.

The antenna moved about 10 feet higher on my little tower recently.

Going to try different PS and plug it into a different circuit later.

d119 · Post by **d119** » Sun Nov 30, 2014 2:55 pm

Have you looked at the input frequency with a spectrum analyzer connected to the repeater antenna?

It's entirely possible that it's on-channel garbage that replacing parts isn't going to do anything about.

Check the spectrum before you check your equipment. GMRS is likely plagued with junk just like Part 15 ISM...

Renamon · Post by **Renamon** » Sun Nov 30, 2014 3:59 pm

d119 wrote:Have you looked at the input frequency with a spectrum analyzer connected to the repeater antenna?

Have not done that yet. Machine has been on this frequency for about 6 months with no issues, only recently. Still, your idea is very possible.

New PS, different circuit, running in CSQ (and having subscribers only emit CSQ) did nothing.

Called a friend down at the local shop, told her the situation and discussed what we did when we tuned it. Since the clicking gets louder and louder as the signal gets poorer, we are thinking something to do with RSSI? Anyway, going to take it down tomorrow and put it on antennas there and see if we can replicate it. Also will run through the alignments again and see if we missed anything. Thinking that maybe we did and since everything else is spot on now, something amiss is more pronounced. Kinda like if you replace all but 1 hose on your car at the same time... (<-- Does that make sense, or am I just crazy?)

d119 · Post by **d119** » Sun Nov 30, 2014 4:01 pm

It's on-channel interference, my man... Tearing your radio apart and realigning it over and over and over isn't going to solve anything. That's some sort of spread spectrum crap that isn't associated with your repeater or station at all.

Since it's GMRS, try changing frequencies for a day. See if it's there or not there on other frequencies.

In addition, connect a receiver (NOT the repeater) to the repeater antenna, listen to the input frequency of the repeater with the receiver, and have someone with a weak signal transmit on that frequency. Is the noise present on this other receiver?

I bet it is...

Guess what? We just eliminated your equipment.

Good luck fixing this - we see this crap in Part 97 UHF here ALL the time. It's always Government stuff. In your case, considering it's GMRS, I'm guessing it's something else.

Bill_G · Post by **Bill_G** » Sun Nov 30, 2014 4:05 pm

Spec analysers often don't go low enough to see interference below -100dbm. Do a rcvr desense test to confirm cochannel interference.

Renamon · Post by **Renamon** » Sun Nov 30, 2014 10:26 pm

I tried a couple other GMRS freqs, including the one I used to use that was fine (vice the other machine on it), and the problem remains.

Need to borrow a N - SMA connector to try the "listen on the input freq" idea.

Callin' it a night, gonna mess with it tomorrow.

wx4cbh · Post by **wx4cbh** » Mon Dec 01, 2014 7:59 am

These may sound like stupid questions, but is there a scanner or a two way radio in channel scan mode nearby? Is there an LED light nearby? I have an older Uniden scanner and an Alinco DR605 that both cause the same sort of popping sound in nearby receivers.

As to the LED lights, after weeks of frustratingly fruitless attempts, I finally tracked down the source of this noise in my truck radios, including the OEM AM/FM radio. The troubleshooting difficulty was that it only occurred in the truck when the brakes were applied. Turned out to be the third brake light on the Leer cap. I replaced it with a cheap $12 unit from an parts store just see if that would make any kind of difference. It did cure the noise. I later piddled with it on the bench oscilloscope and discovered the noise came from the original light because of one non-functioning led that was causing the oscillation circuit in the light to spike on the burned out LED.

CPD534 · Post by **CPD534** » Mon Dec 01, 2014 1:26 pm

Or Christmas lights nearby? Just a idea. Many years ago we had a old 10 channel crystal controlled scanner that would cause something similar on my work radios when they were nearby and the scanner was scanning. Following the thread. Good luck.

Renamon · Post by **Renamon** » Mon Dec 01, 2014 3:08 pm

So...

Repeater is spot on. Could not reproduce it at the shop with a service monitor or dummy load. Hooked everything back up at home and replaced the antenna with a dummy load, no clicking. So it isn't something right in my little shed. Moved the antenna back down to where it used to be, issue still remains. Hooked up another radio to the antenna and tried every GMRS freq, it is present across all channels.

So it has to be something new to the area in the past month or so. Going to do a little hunting and see what I can find.

Random idea: Does anyone know what PAVE PAWS or SSPARS interference sounds like?

Renamon · Post by **Renamon** » Mon Dec 01, 2014 3:29 pm

d119 wrote:It's on-channel interference, my man... Tearing your radio apart and realigning it over and over and over isn't going to solve anything. That's some sort of spread spectrum crap that isn't associated with your repeater or station at all.

Since it's GMRS, try changing frequencies for a day. See if it's there or not there on other frequencies.

In addition, connect a receiver (NOT the repeater) to the repeater antenna, listen to the input frequency of the repeater with the receiver, and have someone with a weak signal transmit on that frequency. Is the noise present on this other receiver?

I bet it is...

Guess what? We just eliminated your equipment.

Good luck fixing this - we see this crap in Part 97 UHF here ALL the time. It's always Government stuff. In your case, considering it's GMRS, I'm guessing it's something else.

I kinda wish you had been wrong, since it would have been easier to fix if it was an equipment issue!!!

Bill_G · Post by **Bill_G** » Mon Dec 01, 2014 7:11 pm

Can you hear it on the ground with a portable, or do you have to be plugged into your antenna at elevation to hear it? Sounds like a fox hunt to me. Those are always fun. Break out the scanner and yagis.

Bill_G · Post by **Bill_G** » Mon Dec 01, 2014 7:44 pm

Reminds me of a school bus customer we gained a couple years ago. We have these lumpy mountain thingies around here that can make propagation and isolation strange at times. All kinds of opportunities for good coverage, no coverage, and lucky coverage. In this case unlucky coverage.

The school district had been running UHF simplex for years. Okay coverage in the valley. Terrible to none as they crawled through the hills. So, our competitor sold a repeater. Put it at a school on a hill giving it about 600 feet over the valley. Pretty good coverage. Filled a lot of holes in the hills. Worked everywhere except the bus yard where the base was. You couldn't understand a single word. But, if you switched to simplex, it worked fine. They lost all the repeater advantage, but they could talk as far as they always had. The competitors never figured it. Our salesman didn't understand it. He wanted to sell a new repeater. Our junior tech didn't understand it. He figured out it was cochannel interference, but once you got away from the yard, it was gone. So, it had to be in the yard someplace. He just couldn't locate it.

Wrong.

Turns out that a long time ago a cable company 30 miles away had a repeater on that pair. They were bought out by Comcast, and they quit using the repeater. They moved to mobile data over LTE. The license lapsed. Years later our competitor got a license on that pair for the school buses, but they didn't check the expired list for those freqs within a 75 mile radius. AND, they got lucky picking the same PL as the old cable company. AND, where the bus yard sits is a lucky shot towards the old cable company repeater which was still running on a hill in a shack on Comcast property untouched after all these years. Still chugging along. So, depending on where the buses were at, they may or may not bring up the cable repeater, but the base and any bus in the yard definitely did. Every time.

It was a mess until we got Comcast to shut it down.

I can think of at least two other similar incidences where the customer's base station antenna could hear cochannel repeaters, but you couldn't hear it on the ground. They caused intermittent degradations and noises the dispatchers tried to ignore until it would get bad from an inversion that tunneled them in really strong for short periods of time. I love chasing that stuff down.

KE7JFF · Post by **KE7JFF** » Mon Dec 01, 2014 8:26 pm

Bill_G wrote:Reminds me of a school bus customer we gained a couple years ago. We have these lumpy mountain thingies around here that can make propagation and isolation strange at times. All kinds of opportunities for good coverage, no coverage, and lucky coverage. In this case unlucky coverage.

The school district had been running UHF simplex for years. Okay coverage in the valley. Terrible to none as they crawled through the hills. So, our competitor sold a repeater. Put it at a school on a hill giving it about 600 feet over the valley. Pretty good coverage. Filled a lot of holes in the hills. Worked everywhere except the bus yard where the base was. You couldn't understand a single word. But, if you switched to simplex, it worked fine. They lost all the repeater advantage, but they could talk as far as they always had. The competitors never figured it. Our salesman didn't understand it. He wanted to sell a new repeater. Our junior tech didn't understand it. He figured out it was cochannel interference, but once you got away from the yard, it was gone. So, it had to be in the yard someplace. He just couldn't locate it.

Wrong.

Turns out that a long time ago a cable company 30 miles away had a repeater on that pair. They were bought out by Comcast, and they quit using the repeater. They moved to mobile data over LTE. The license lapsed. Years later our competitor got a license on that pair for the school buses, but they didn't check the expired list for those freqs within a 75 mile radius. AND, they got lucky picking the same PL as the old cable company. AND, where the bus yard sits is a lucky shot towards the old cable company repeater which was still running on a hill in a shack on Comcast property untouched after all these years. Still chugging along. So, depending on where the buses were at, they may or may not bring up the cable repeater, but the base and any bus in the yard definitely did. Every time.

It was a mess until we got Comcast to shut it down.

I can think of at least two other similar incidences where the customer's base station antenna could hear cochannel repeaters, but you couldn't hear it on the ground. They caused intermittent degradations and noises the dispatchers tried to ignore until it would get bad from an inversion that tunneled them in really strong for short periods of time. I love chasing that stuff down.

Bill, you just reminded me of something....

Renamon, can you get a recording of the clicking and post it here?

Bill_G · Post by **Bill_G** » Mon Dec 01, 2014 9:13 pm

He did. It's above. He uploaded it to YouTube.

Renamon · Post by **Renamon** » Mon Dec 01, 2014 9:39 pm

Here you go: https://www.youtube.com/watch?v=usG7aUWKAt8

KE7JFF · Post by **KE7JFF** » Mon Dec 01, 2014 9:45 pm

Renamon wrote:Here you go: https://www.youtube.com/watch?v=usG7aUWKAt8

Thanks...I should of noticed that in the start of this thread.

Well, its not exactly I was thinking of, but something else that comes to mind...is there a wireless weather thermometer or weather station nearby?

Renamon · Post by **Renamon** » Tue Dec 02, 2014 6:57 pm

KE7JFF wrote:Well, its not exactly I was thinking of, but something else that comes to mind...is there a wireless weather thermometer or weather station nearby?

No, it is the only electrical thing in my shack running right now. Nothing else nearby that I can find that would cause it.

d119 · Post by **d119** » Wed Dec 03, 2014 8:26 am

Have you hooked up that receiver and run a weak signal into it yet????????????????????????????????????????????????????????????????

Renamon · Post by **Renamon** » Thu Dec 04, 2014 4:20 pm

d119 wrote:Have you hooked up that receiver and run a weak signal into it yet????????????????????????????????????????????????????????????????

Yeah, it is present on the other receiver when hooked up.

Renamon · Post by **Renamon** » Thu Dec 04, 2014 4:37 pm

Well, I hooked up another receiver to the antenna and had a unit far away xmit and I heard it on their inbound signal...

d119 · Post by **d119** » Thu Dec 04, 2014 8:52 pm

Then it's not your problem.

Well, I mean it is, but it isn't, you know what I mean? LOL...

You've eliminated your equipment as the source of the problem, so your installation is good. Good luck getting the FCC to lift a finger on GMRS interference though.

It's entirely possible this is something that's intended for licensed channels or something else that someone installed somewhere and "parked" on the GMRS channels since they are considered to be "license free" or "CB" to some.

You'd be surprised how many mom & pop shops place people on FRS frequencies...

Post by **escomm** » Thu Dec 04, 2014 8:55 pm

You'd be surprised how many MSS put people on FRS and MURS frequencies

Bill_G · Post by **Bill_G** » Fri Dec 05, 2014 5:27 am

But, he said he changed freqs, and it was there too. Must be rather broadband fubar generator.

d119 · Post by **d119** » Sun Dec 07, 2014 6:36 pm

escomm wrote:You'd be surprised how many MSS put people on FRS and MURS frequencies

Not this one, that's for sure.

Renamon · Post by **Renamon** » Tue Dec 09, 2014 12:56 pm

I am going to keep an eye on it over the next couple months and see if anything changes. I will update the thread (if it still exists) with anything new.

Hopefully, it is just something temporary. I am thinking about switching the input/output freqs and switch the duplxer cables and see if it is something that is present all over up where the antenna is.

Renamon · Post by **Renamon** » Mon Dec 29, 2014 1:46 pm

Update: So as of yesterday (Sunday 12/28) the clicking seems to have moved on. This machine doesn't get used much at all (and I haven't used it in almost a month), so it may have gone away weeks ago and I wouldn't have ever known.

Anyway, for now it seems like the interference has self-resolved. Lets hope it stays away!

mac1_131 · Post by **mac1_131** » Thu Jan 15, 2015 12:19 pm

you're lucky it stopped. we have a similar clicking and popping all over the 420-440 segment of the ham band here that causes a similar noise on any UHF repeater input or link frequency that happens to be in that range.

we've been trying to find it for a couple years, even had the FCC involved on and off, still haven't found it. seems to be coming from some gov't towers in the area, so we assume it is spread spectrum. you can see it on an analog service monitor that refreshes fast enough. hard to see on software driven digital spectrum analyzers...