Tone control Mystery Theatre

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Bill_G
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Tone control Mystery Theatre

Post by Bill_G »

It was a dark and stormy night, with a lot of snow, and overall kind of normal for the middle of winter. Even the guys in Atlanta are getting to know this part of the story. No mystery there.

Where I do have a mystery is why a tone remote will not key up a base station through the telco leased line.

Nothing special about the setup. Kenwood base station at a remote site connected to a CPI TTP1 (tone termination panel). 2W telco leased line down to their office 15 something miles away. Plain vanilla Command Series tone remote that only boogies F1 1950 and Monitor 2050.

They can't key the station. Rx audio is good. Line loss in both directions is -14db (acceptable). There is no twist or translation. 1004 is 1004 in both directions. 2175 is 2175 in both directions. LLGT shows up at the site at -27db (acceptable). Tones sound good on the line. Voice sounds good. Take the CPI to their office, and their tone remote can key it. Take their tone remote to the site, and it keys the station. Swap out the CPI - get the same results. Swap out the tone remote - get the same results. Adjust levels up and down - get the same results. The phone company has looked at the circuit twice - no trouble found, and no change in operation.

What am I missing?
gtriever
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Re: Tone control Mystery Theatre

Post by gtriever »

I don't like that -14dB loss, Bill. When dealing with leased lines, we always specify a 0dB/0dB circuit. I'd take a look at the keying sequence at the remote and at the site with a storage scope, to see how much distortion is on the function tone.
Jim202
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Re: Tone control Mystery Theatre

Post by Jim202 »

Have you tried to measure just the low level idle tone level at both the origination point and the distant point? This level should be in the -27 to a -35 level at the radio. Anything lower than the -35 at the radio end and you probably won't key the radio reliably.

In all my travels around the country installing radio interoperability gateways, I have found these levels to be all over the board. Motorola will tell you right in their manuals that the radio will not key below a -40 low level guard tone. So you need to keep some sort of buffer built into where you adjust the origination point levels.

The phone companies are also real bad at maintaining the audio levels on their radio links. You have to watch over the shoulder of the tech that comes out to set the levels in their end termination units. Make sure that you don't settle for their normal line losses. Like someone else pointed out, if you put a tone on at 0 db at the origination point, make the phone tech set his equipment to give you the 0 db out at the radio end.

Once you have a good path, you can trouble shoot the radio tone control problem. I always just tell who ever is working with you to key the console and don't have any audio going into the mic. This way you have the 2175 low level tone to adjust everything to. I like to see a -27 db level for this tone.

Another point to be aware of is to make sure that your test meter being used to measure the tone level is in the bridged mode. If you have it in the terminate mode, you load down the line and will get a wrong reading. Have seen even the telephone tech go down in flames over this simple goof up. This also is done with all the normal stuff attached to the phone line like the radio and the originating console.

Jim
RFguy
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Re: Tone control Mystery Theatre

Post by RFguy »

gtriever wrote:I don't like that -14dB loss, Bill. When dealing with leased lines, we always specify a 0dB/0dB circuit. I'd take a look at the keying sequence at the remote and at the site with a storage scope, to see how much distortion is on the function tone.
We typically see/specifiy -10 for lease lines. As soon as you start to put gain in the lines (which you have to do to get 0 end-to-end), then there are issues with stability. If we are in-building and expect near 0 loss, then we turn the TX level down by 10 dB.

You should be good down to 20 dB line loss, as long as there isn't line noise. We have systems in place that have been running 20 dB line loss for years and we only have problems with them when there us a line fault causing hum/noise.

The storage scope is a great idea. I have a older Fluke model 123 hand held storage scope that I use to trigger on the keying tones to "capture" the keying sequence HLGT, FT and LLGT levels, duration, quality.

It has often caught strange issues with levels.

The tone sequence generated at the remote upon PTT switch operation typically is 2175 Hz at +10 dBm for 130 ms (High Level Guard Tone), followed by a function-tone frequency at 0 dBm for 40 ms, followed by 2175 Hz at –20 dBm (Low Level Guard Tone) for the duration of PTT-switch operation.

Look for the levels and durations at the remote and adjust accordingly, then recheck the same at the base station end and compare relative levels.

Good luck.
MassFD
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Re: Tone control Mystery Theatre

Post by MassFD »

I know you said you adjusted the levels both up and down but what is the level of the 2175 and 1950 tones, is it over 0db?

The reason I ask is if the telco is converting your copper to Fiber transport then back to copper their equipment may clip (flat top) anything you put into it over 0db

I know many of the microwave transports get very flakey over 0db but since they are loss less there is no reason to run that high anyway.
Cause Motorola said so that's why
gtriever
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Re: Tone control Mystery Theatre

Post by gtriever »

We specify 0/0 in part because we run a mixed microwave/leased line system and it simplifies adjustments and troubleshooting. Honestly, with a 0dB level we rarely see any issues. Usually when we do it's because the "phone guy" has dropped a +8 on us. As far as tone remote levels, we run 0/-10/-30; I hate running a +dB level on anything because of distortion and clipping issues, which I suspect in Bill's case here.
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The Pager Geek
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Re: Tone control Mystery Theatre

Post by The Pager Geek »

Assumptions:
- If the Tone remote is set for -20LLGT: (some are -30 which makes it worse in this case)
- If there is -14db line loss:

The levels going INTO the 2wire circuit are:

HLGT is +17
Function tone is +7
LLGT is -13 (results in a -27 on the far-end)

= bad (too hot)

If you can put a scope on it, I bet the function tone is distorted on the radio end....

tpg
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Bill_G
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Re: Tone control Mystery Theatre

Post by Bill_G »

Great. Thanks. I knew I was off my game. I just spent the last four days working through the flu, but was feeling it Monday and Tuesday when I first got this tone control problem. I am pretty certain I tried turning things down, but it's worth a second look.
CPIComm
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Re: Tone control Mystery Theatre

Post by CPIComm »

Most likely TTP1 "Line In Adjustment" needs to be performed, with it installed in the system, to accept the level coming in from the tone remote. Below is the link for the manual. The line in adjust procedure can be found on page 3.

http://www.cpicomm.com/ttp1-ttp2manual.pdf
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Bill_G
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Re: Tone control Mystery Theatre

Post by Bill_G »

Got it. Did that. Didn't work. Which may or may not put the keybosh on the levels being too high. What I did see in the manual was several alignment points which should make good places to monitor what the TTP is seeing coming at it down the line.
CPIComm
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Re: Tone control Mystery Theatre

Post by CPIComm »

If you were able to adjust R64 to the measurements indicated in the manual then I looks like it points back to the line being the issue. Possible solution if unable to narrow it down is use the newer TTP1N version which has automatic gain control for the incoming tones.
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The Pager Geek
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Re: Tone control Mystery Theatre

Post by The Pager Geek »

Bill_G wrote:Great. Thanks. I knew I was off my game. I just spent the last four days working through the flu, but was feeling it Monday and Tuesday when I first got this tone control problem. I am pretty certain I tried turning things down, but it's worth a second look.
I'm not sure turning it down will help unless you can somehow adjust the termination panel to see very low levels. I agree it's a line loss issue...

If the TRC is set for "default":
HLGT = 0
Function = -10
LLGT = -30

The termination end would see:
HLGT = -14
Function = -24
LLGT = -44

I'm not sure the termination panel would be "see" those levels correctly. You would have to adjust the termination panel for levels under those conditions, not 0/-10/-30. You might be able to go 10db higher on the TRC end, but you risk distorting the HLGT.

Food for thought...
tpg
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Bill_G
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Re: Tone control Mystery Theatre

Post by Bill_G »

Well, apparently they got it fixed while I was in the hospital. I heard it on the air. I know their regular tech. I'll ask him what he did.
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FMROB
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Re: Tone control Mystery Theatre

Post by FMROB »

Hospital, yikes. I hope all is well Bill!
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Bill_G
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Re: Tone control Mystery Theatre

Post by Bill_G »

FMROB wrote:Hospital, yikes. I hope all is well Bill!
I'm fine ... now. I kinda overdid it during our recent snowpocalypse. The freeze busted a pipe under my house, and under my neighbor's house. Those were a blast to fix. And then there was all the chasing over hill and dale with the day job cuz ice breaks stuff. You get to 60, and you're not supposed to be on your face in mud in a crawl space, or digging out stuck trucks with busted chains, or four wheeling to mountain tops in a blizzard. You get that pneumonia stuff, and then an all expenses not paid trip to the hospital. Good times.
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d119
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Re: Tone control Mystery Theatre

Post by d119 »

Bill_G wrote:
FMROB wrote:Hospital, yikes. I hope all is well Bill!
I'm fine ... now. I kinda overdid it during our recent snowpocalypse. The freeze busted a pipe under my house, and under my neighbor's house. Those were a blast to fix. And then there was all the chasing over hill and dale with the day job cuz ice breaks stuff. You get to 60, and you're not supposed to be on your face in mud in a crawl space, or digging out stuck trucks with busted chains, or four wheeling to mountain tops in a blizzard. You get that pneumonia stuff, and then an all expenses not paid trip to the hospital. Good times.
Glad you're OK, William.

So what about the TRC issue? What was it?
Jim202
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Re: Tone control Mystery Theatre

Post by Jim202 »

Bill_G wrote:
FMROB wrote:Hospital, yikes. I hope all is well Bill!
I'm fine ... now. I kinda overdid it during our recent snowpocalypse. The freeze busted a pipe under my house, and under my neighbor's house. Those were a blast to fix. And then there was all the chasing over hill and dale with the day job cuz ice breaks stuff. You get to 60, and you're not supposed to be on your face in mud in a crawl space, or digging out stuck trucks with busted chains, or four wheeling to mountain tops in a blizzard. You get that pneumonia stuff, and then an all expenses not paid trip to the hospital. Good times.



Bill, don't you know us old farts are not the young chicks we use to be. I get yelled at all the time by the other half, when I even get up on a step ladder. Going to be interesting come spring when I want to put up a tower.

You have to keep dressed for the weather and let the young kids do the mud crawl. Shoveling snow is OK as long as you do it slowly and not get the blood pressure up too high. I still put many of the young kids to shame trying to keep up with me.

Jim
GlennD
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Re: Tone control Mystery Theatre

Post by GlennD »

No kidding age creeps up on everyone. I just had a visit from a Long Beach tech that lives near me. He tripped and fell in the park while walking his dog. It caused a black eye, bruised face, broken wrist, and hyper extended toes.

The sad thing is that he is 66 like me. Years ago this would be a swear word and just dusting off.



Jim202 wrote:
Bill_G wrote:
FMROB wrote:Hospital, yikes. I hope all is well Bill!
I'm fine ... now. I kinda overdid it during our recent snowpocalypse. The freeze busted a pipe under my house, and under my neighbor's house. Those were a blast to fix. And then there was all the chasing over hill and dale with the day job cuz ice breaks stuff. You get to 60, and you're not supposed to be on your face in mud in a crawl space, or digging out stuck trucks with busted chains, or four wheeling to mountain tops in a blizzard. You get that pneumonia stuff, and then an all expenses not paid trip to the hospital. Good times.



Bill, don't you know us old farts are not the young chicks we use to be. I get yelled at all the time by the other half, when I even get up on a step ladder. Going to be interesting come spring when I want to put up a tower.

You have to keep dressed for the weather and let the young kids do the mud crawl. Shoveling snow is OK as long as you do it slowly and not get the blood pressure up too high. I still put many of the young kids to shame trying to keep up with me.

Jim
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