Yamhill County UHF system - why does it always seem to have comparatively low audio?

[parallax]

So what's up with the audio on the Yamhill County public safety communications system? It seems like nearly all equipment on all their channels is under-deviated. I have lots of systems programmed into my 996XT (including a number of other 460 MHz systems) and Yamhill County always has the noticeably lowest audio of them all. In fact their low audio consistently causes me the need to twist up the volume knob when the scan stops on one of their channels. And by the way, the signal strength of their UHF system is usually full bars at my location. As I remember, their old VHF low-band system used to have great, adequately loud audio. So what gives and why am I seemingly the only one who notices this YCOM weak audio phenomenon?

Additionally, are they using OPS 3 (460.100) for SO dispatch now? All the dispatch activity seems to be on that freq lately for some reason. I thought the main SO dispatch freq was supposed to be 460.1875 as it seemed to be several months ago.

 

[trumpetman]

The only thing I can guess is maybe there's a difference in deviation? Narrowband radios going into a wideband repeater, or wideband radios going into narrowband repeater. I'm not sure either way.

The one thing I CAN contribute to this question is that the XT scanners have an audio adjustment on a per channel basis. Saved me a lot of trouble when I listened to similar systems. It kept me from constantly turning the volume up and down and creating wear and tear, and even more importantly it kept me from cranking the volume up and getting blown away when it stopped on a new agency (spooked me every damn time).

 

[mikepdx]

Adjust Audio AGC in the menu system.
It has separate analog and digital AGC adjustments

From the Easier to Read BCD996XT Digital Scanner Manual
AGC Instructions here

It is important that you correctly set the modulation type for the channel you are programming. If you
program a channel as NBFM that is transmitting in FM mode, the audio will sound too loud as compared to
correctly programmed channels. Similarly, if you program a channel as FM that is transmitting in NBFM
mode, the audio will be too quiet as compared to correctly programmed channels. Incorrectly matching the
modulation setting to the actual modulation used is the biggest reason for unbalanced audio between
channels.

 

[parallax]

Hey thanks for the replies, guys.

Well, the modes for the Yamhill UHF group are all set to AUTO, which seems to be the default. If the entire system (or most of it) is in fact nFM, I guess that could explain things. I thought the AUTO mode would auto-select the bandwidth based on whether or not a frequency was a splinter (i.e., one ending in .xx25 or .xx75 on the 460 MHz band). And I thought 6 kHz was the normal non-splinter deviation for land mobile FM on that band. But at any rate I guess the thing to do is try setting the UHF YCOM freqs to nFM I suppose.

And, yes, I could also adjust the individual channel audio levels to match the audio levels of everything else. But my concern with that would be that the squelch breaks would then become significantly louder, which could prove to be rather unpleasant. I wish there were a way to make the CTCSS decoder drop milliseconds before the carrier squelch mutes and do it on a consistent basis (like most commercial radios do). That way I wouldn't have to worry about hearing squelch breaks on the conventional systems, loud ones or otherwise.

 

[PMJ2kx]

I set mine to Auto, FM, and NFM. No change in overall audio quality. In fact, Ops 3 is a lot louder than I remember LAW to be.

But yeah, I know what you're talking about.

 

[parallax]

I set mine to Auto, FM, and NFM. No change in overall audio quality. In fact, Ops 3 is a lot louder than I remember LAW to be.

Yeah, it's about the same for me. The Auto option seems to select nFM on the splinters automatically (hence the term "AUTO"), so there's no difference.

I think one thing that's a factor in my case (to some degree, at least) is that I'm getting multi-path signals from some of YCOM's xmitter sites. I live between several hills and the signals bounce off of them a lot giving me late-arriving versions of the same signal from multiple directions. If YCOM's default is to simulcast from multiple sites then I'm sure that only serves to compound this issue for me. In the past I've found that multi-path signals can counter the effects of adequate deviation. So maybe that's the main issue here.

I use the scanner as a fixed base unit. I have it on an external antenna but I should probably experiment with different antennas / antenna locations to confirm or deny how much the multi-path factor is to blame.

By the way, does anyone know if / when YCOM is moving back to 460.1875 (Law Dispatch) from 460.100 (OPS 3) as their main frequency? I'm wondering if they might have changed permanently to 460.100 since they should be able to legally use more deviation on that freq than on .1875.

 

[Gezelle007]

...If YCOM's default is to simulcast from multiple sites then I'm sure that only serves to compound this issue for me. In the past I've found that multi-path signals can counter the effects of adequate deviation. So maybe that's the main issue here...

...By the way, does anyone know if / when YCOM is moving back to 460.1875 (Law Dispatch) from 460.100 (OPS 3) as their main frequency?...

The system is a simulcast system and they do have the ability to turn off and on different sights. And I believe they are using OPS 3 while McMinnville's new simulcast channels get added.

And yeah I agree PMJ2kx, OPS 3 is way louder than any of them. FIRE being the quietest in my area.