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Narrowbanding with Quantar poor audio

This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.

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Mraudio
Posts: 99
Joined: Sun Jan 27, 2008 6:48 am
What radios do you own?: Quantar/AS/A-spec./VertexP25

Narrowbanding with Quantar poor audio

Postby Mraudio » Wed Aug 09, 2017 7:00 am

Hello all,

Have been cleaning up a guys work here in the county that left and found that he left all the county's Quantar stations set to 4k deviation not 2.5. I have 3 systems that use the JPS SNV12 voter and telco for transport of all the audio and signaling. I have been going through getting all the RX levels to the voter to arrive at my 66 block to the voter at -20 for 1.3k, so that is leveling out the mis-voting. Running all stations with demph audio, and pre emph still enabled on the stations with the notch filters since were running status and keying tones across the lines, changed the TX audio to 2.5k from 4 and have lost definition to the audio. In other words it now sound very flat and not having much articulation.

Question(s) I have here is that in the narrow mode I have noticed in the TX wireline setting unlike wide band there is almost ZERO difference on what input level you drive the line at to achieve 1.3k of deviation at 1k. I have experienced this in 5 stations now.

Additionally I have noticed a loss of fidelity to the systems transmitted audio? I know its less audio but I didnt expect to hear so much difference in the quality of the repeated audio. My MDC muting isn't functional on my portable like it once was either. Is this normal? I have swept he phone line too look for roll off on the lines and some may have 1-2 db on the low end but still seem to hold fine above 1khz. I do not have AUTO or AGC enabled on the station wireline anywhere in the RSS.

Am I missing something? Thanks!

User avatar
chartofmaryland
Batboard $upporter
Posts: 400
Joined: Sat Dec 28, 2002 11:25 pm
What radios do you own?: Alot

Re: Narrowbanding with Quantar poor audio

Postby chartofmaryland » Sun Aug 13, 2017 5:41 am

Morning Mraudio,

First thing I can recommend as my opinion only is to enable AUTO for the transmit wireline level.

Motorola Eng. during the Quantar days did a fine job in creating this setting.

If the few things I will never fully understand about the Quantar, the AUTO transmit line level control will be one of them. That setting works great and has been consistent for when I set levels. I "went manual" one time and fought the beast to align levels to something that sounded good. Lost that fight and 4 days of trying to align by myself.

Enabled the AUTO and was wrapping cables on the helper lineman to be put away in about 2.5 hrs.

When you speak of audio changes I hope you are reprogramming your subscriber fleet as well.

In addition if you are having the SNV-12 control the repeat audio than it is said you checked the switch settings for wide vs narrow audio and that your cards are setup for -13 vs 0 dbm configuration.

Your SNV-12, is this single chassis? Rules change when you have multi-chassis setup.

Will have to go back to the SNV manual to check a few other things and report back

CoM
If the lights are out when you leave the station and then come on the second you key up, you know you have enough power.


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