MTR2000 Console Auidio

[graysharbor]

I've read through the topics here and haven't found the answer for what I'm experiencing or that I;ve seen anyways.....
I've had MTR2000's in service for many years as bases, repeaters, and simulcast systems. One thing I've never cured was the console audio sounding as clear as any other station types we have in our county.
I'm fairly familiar with the wireline and deviation alignments as I've had many bench hours manipulating them. No matter how I've tried aligning I've never made the console tx audio sound like it should.
I'm wondering if possibly not using any of the audio settings could be causing this issue? I haven't tried using emphasis on the stations but am wondering if that could help? Or another wireline setting?
All other audio from field units sounds great going through the same voter as the console is interfacing at the same levels.
Any help would be greatly appreciated!

[Bill_G]

Is the console inserting at the comparator (voter) or parallel to it?

What quality is the console audio? Is it loud and distorted? Too soft? Boomy? Super crispy?

[graysharbor]

Depends on system but some at the JPS console input and others it's 2 or 4W from the Zetron channel cards over microwave to the radio.
I've tried adjusting different systems with -15dbm to -5dbm as average voice modulation levels with no change in audio quality from dispatch.
I've tried lowering the level at the console and at the JPS output level with no change except lower modulation with the same audio quality.

The audio seems very monotone and muffled. Closest comparison would be the parents on Charlie Brown....
At first I believed it was overdriven audio because that's what it's most comparable to.
The same setups work great with MastrIII stations and Motorola control stations which are mobiles.

[d119]

And you did perform the TX wireline adjustment by sending it -10 @ 1000Hz and telling it that you were doing so, right?

On systems using a voting comparator where you are using console priority and feeding the console into the voter, how does the voted audio sound?

If the voted audio is fine, but the console is not, the problem isn't in your MTR 2000.

I have an MTR 2000 with a comparator and a console on it personally, and I've worked on more MTR's with consoles than I can think about, and I've never had the issues you speak of.

Is this one particular console feeding all of this that you're having issues with, or is it different systems / different console manufacturers, etc?

I would think you would want de-emphasis and pre-emphasis turned ON across the board. That's the standard. And probably part of your problem.

[graysharbor]

And you did perform the TX wireline adjustment by sending it -10 @ 1000Hz and telling it that you were doing so, right?
Yes I did the wireline adjusting the way you mention as well as manipulating it a bit to get exactly how I'd like along with manipulating modulation settings approximately 500 lower than actual measures to get more modulation at the level I need for simulcasting..

On systems using a voting comparator where you are using console priority and feeding the console into the voter, how does the voted audio sound?

If the voted audio is fine, but the console is not, the problem isn't in your MTR 2000.
I understand what you're saying and I've thought the same thing. Voted audio is fine so what's wrong with console audio? All other systems using same console interface, same comparators, sound fine. Just the MTR doesn't sound quite right

I have an MTR 2000 with a comparator and a console on it personally, and I've worked on more MTR's with consoles than I can think about, and I've never had the issues you speak of.
I know that it's something I've done for it to be occurring it's just very strange it's only on the systems with MTR's. I had a Motorola vendor give me advice and still haven't found the cause. I'm starting to think maybe the gain in the headset jack boxes is possibly too hot for the MTR strangely and not the other radios? Any thoughts to it could have too much gain before getting to the voter or the radio on the wireline bases?

Is this one particular console feeding all of this that you're having issues with, or is it different systems / different console manufacturers, etc?
One Zetron 4048 Integrator system for the dispatch center feeding all 22 radio channels.

I would think you would want de-emphasis and pre-emphasis turned ON across the board. That's the standard. And probably part of your problem.

I hadn't done this in the years past when setting them up in the lab as I maintain many VHF analog simulcast channels and was a bit concerned it may cause discrepancies from base to base. Also it caused some audio modulation changes especially for QCII and assumed since the subscriber units are doing it already why do it twice....
I know now that it's not that critical on the QCII tones and I'll be trying it soon on one of our systems.

[Bill_G]

I've never had that problem with MTR2k's. They always sounded great. It's possible you have a bad wireline card, but not in every station, except if they are all the same vintage setup by the same guy, and he did them all wrong, or he somehow blew them all up. If the repeaters that run through a voter pass subscriber audio fine, then it's not the wireline card since everything passes through them. -10 in and out at 2/3 dev is pretty standard especially if you have a microwave transport. Lossless system. It might be worth your time to get a known good wireline board, and substitute it into one of your stations.

Have you listened to the line audio with a TMS set to verify the gozintas sound good?

Have you had someone else take a stab at the problem? A fresh pair of eyes sometime finds things.

[graysharbor]

It can't be the wireline card as other audio is fine. The audio isn't terrible and these have been in use for years set up by my predecessor. I've never liked the way the audio sounded compared to our other stations such as the Mastr III and other Motorolas that were aligned in the same fashion. Some field units have complained a little regarding the differenced between channels that use the MTR's vs others.
Since coming to this position I've tried a couple times to realign a system with different levels and mudulations but it always sounds the same. I haven't had emphasis turned on ever so I'm going to try that today on a channel and see how it sounds.
Thanks for all the thoughts on this.

[Bill_G]

I always have pre-emphasis and de-emphasis turned on in every base station with one exception - if the voter or simulcast controller is applying it. My preference is to have the voter and sim ctrl send flat audio into base stations that apply the pre-emphasis. If you have pre-emphasis and de-emphasis turned off in the base stations, and the subscribers sound fine, but the console sounds mushy, then I'm surprised the receive audio at the consoles doesn't sound shrill and high pitched.

Obviously, what is happening is your mobiles are applying pre-emphasis. It's built in. You can't turn it off. They are being being received at a site. The un-de-emphasized audio is faithfully shipped to the voter, which faithfully sends it to a transmitter which does not apply pre-emphasis, over the air to another mobile which applies de-emphasis, and it sounds fine. If you repeat internally at a station, it does the same thing - it turns the pre-emphasized audio around, back out the door, and the mobiles never know the difference. Sounds perfect.

Until you attempt to send console audio through it. The console doesn't get the benefit of the pre-emphasis before it hits the air, but the mobiles still apply de-emphasis. Again, it's built in. You can't turn it off. So, now the consoles sound like mushy garbage.

I'm not certain what your predecessors aversion is to pre- and de-emphasis was, but he did it wrong for a voice system. There is a reason we send flat audio to the stations, and let the radios do the equalization. You turn off the equalization if the stations primarily process data and you don't want the rising edge to be corrupted by the integration introduced by the filters. For voice, leave the filters on.

Hope that helps.

[d119]

To the OP:

What kind of simulcast system are you using? (pure curiosity).

I think you need to be looking more at the consoles than the simulcast/stations. Your problem isn't in your MTR's.

MASTR II/III is fine, but they don't do things the way Motorola does them, with regard to ANYTHING, so it's no wonder you're getting different results with that equipment. Perhaps they handle wireline audio limiting in a different fashion, so you're seeing different results.

To echo my own and Williams statements again, I've done this countless times with MTR's and they always sound great when set up properly. They are perhaps one of the cleanest sounding stations I've ever come across, in fact.

Care to comment on that, William?

[escomm]

Other than not having full deviation the MTR is a great station!!!!

[d119]

Other than not having full deviation the MTR is a great station!!!!

Yeah it does miss a little off the top... I think I only get around 4.3kHz out of mine.

[Bill_G]

Other than not having full deviation the MTR is a great station!!!!

Yeah it does miss a little off the top... I think I only get around 4.3kHz out of mine.

You have to fake them out in the mod alignment by subtracting 500 or more.

[Bill_G]

To the OP:

What kind of simulcast system are you using? (pure curiosity).

I think you need to be looking more at the consoles than the simulcast/stations. Your problem isn't in your MTR's.

MASTR II/III is fine, but they don't do things the way Motorola does them, with regard to ANYTHING, so it's no wonder you're getting different results with that equipment. Perhaps they handle wireline audio limiting in a different fashion, so you're seeing different results.

To echo my own and Williams statements again, I've done this countless times with MTR's and they always sound great when set up properly. They are perhaps one of the cleanest sounding stations I've ever come across, in fact.

Care to comment on that, William?

(looking around for my mother. William?) (snort)

I think he has the MTR's running with pre-emphasis and de-emphasis turned off for some reason, and as I explained before, that does work for subscribers going through a repeater. The subscribers are doing all the work. But, it doesn't work for consoles coming in on the wireline. I can't explain why his GE's sound good unless they don't have the option to turn emphasis on and off. Haven't touched one. Don't know what's inside. I suspect they don't allow it to be turned off, or the option is there, you can click it, but it doesn't go into effect because a data option wasn't purchased. I'm betting if he turns emphasis on in his MTR's, he'll be a lot happier with the console audio.

If he's running simulcast with these, it's probably a Dalman or Simoco system which does all of the equalization for you. Doesn't explain his consoles though. There is a console input on their controller shelf, and it applies equalization to that path too. OTOH, his predecessor may have bypassed the console input, or done something else we aren't aware of. We've all come in behind some guy who insists on doing things his way even when it's incorrect.

[d119]

(looking around for my mother. William?) (snort)

If he's running simulcast with these, it's probably a Dalman or Simoco system which does all of the equalization for you. Doesn't explain his consoles though. There is a console input on their controller shelf, and it applies equalization to that path too. OTOH, his predecessor may have bypassed the console input, or done something else we aren't aware of. We've all come in behind some guy who insists on doing things his way even when it's incorrect.

Could be a Tait or Motorola simulcast as well... There are others.

Dalman COSMOS... Yuck.

[Bill_G]

(looking around for my mother. William?) (snort)

If he's running simulcast with these, it's probably a Dalman or Simoco system which does all of the equalization for you. Doesn't explain his consoles though. There is a console input on their controller shelf, and it applies equalization to that path too. OTOH, his predecessor may have bypassed the console input, or done something else we aren't aware of. We've all come in behind some guy who insists on doing things his way even when it's incorrect.

Could be a Tait or Motorola simulcast as well... There are others.

Dalman COSMOS... Yuck.

Yeah, but their Little Gem equalization alignment tool is fantastic. You can dial in individual transmitters perfectly every time. I use it on every analog simulcast now. Totally gets rid of overlap zones. Seamless transitions.

[d119]

Details?

[graysharbor]

They are analog VHF simulcast using convex CTU/ADL for the timing. The console audio is using the CIM card of the JPS voters with no special provisioning. There isn't any equalization for the audio and I'm thinking the mushy sound is because of the non emphasis on the stations. I've been swamped with other projects but will hopefully get to changing one of the systems and listening to the outcome. I'll post my results.
Thanks for all the comments regarding this. I agree that the audio is great for the subscriber audio and know it's definitely on the console side somehow if the emphasis doesn't work.

[Bill_G]

Details?

No longer available, but I'll dig up what I have from the Cosmos books.

[graysharbor]

The emphasis was the key, made all the difference.
Wasn't fun finding one of the MTR's had the Aux TX Audio setting to "same as wireline". We run the onsite PL into this input and before with no emphasis it didn't matter. With 5 sites TX simulcasting that made the audio interesting......