UPMAN, UPMAN...How Copy? Over.

[blueline_308]

Need help with C Ch. issues. Help UPman

Upman, I hope that you or some of your buddies at Uniden can help me address this problem.

In my area, there are several Mot 800 TRS that share some of the same freqs. If I have system A programmed for CC only, and system B programmed for CC only, when sys A locks onto one of its voice channels that just happens to be the CC for sys B, it stays locked on to that freq, even if the CC data is much weaker, close to equal, or stronger than the voice signal. It will display the sys info for sys A and a TGID that doesnt match either sys. Is there anything like data skip for TRS? Shouldn't it recognize the RX signal as CC data and mute and resume scanning?

Im using a 996.

Please help me with this.

Thanks,
Jim

 

[musicman476]

Jim,

One thing that would aid UPMan or others in helping you is to tell us what kind of scanner you have. Thanks!

 

[blueline_308]

OOPS....Its a 996.
Thanks for the reminder.

 

[DaveIN]

Is this a Viper site or something else?
http://radioreference.com/modules.php?name=RR&sid=4087

Maybe you should also try the North Carolina forum.

 

[blueline_308]

I dont think its specific to NC. There must be other sites where this is possible. The problem isn'y really with the allocation of frequencies, but rather with the scanner not muting and resuming upon the detection of a control channel. See, if you only have one freq programmed or unlocked within a site ( the CC ), then whenever CC data is recognized on a freq other than the one programmed or unlocked, it should mute and resume, but it doesn't. I have heard of others having CC problems, and I bet if the research was done, they may find that its a freq of another site thats locking it up.

 

[DaveIN]

The sites should be far enough apart not to bleed over into each other. Other statewide systems repeat frequencies and do not overlap in coverage.

One other thing to try is the attenuator. You may not be able to use the control channel only feature, but you could attenuate the offending channels. Here in Michigan and in Indaina the repeat frequencies and I have not had the problem.

 

[blueline_308]

Well Dave, they do 'bleed over'. I understand how frequency coordination is supposed to work, but there are only so many freqs to go around, but again, thats not the issue here. DX'ing is a major interest for me. When the band opens up, as it has a few times recently, it makes trunk scanning near impossible. An example was this morning, my Viper sites were locking up all over the place, so I rotated the yagi, and lo and behold it was sites within the SC Palmetto system 150 miles away...so I monitored them for awhile.

 

[bonus1331]

Hey Blueline,
Your complaining?
I live 15 miles from the SC border and can't get a Palmetto800 signal using the ducky on my 330, 396, or BCT-15.
Thats' quite a yagi you've got!

 

[blueline_308]

Its just a Wilson 800 MHz Yagi at 25' AGL fed with LMR-400. I'm happy with it. Bear in mind that I cannot 'normally' hear them, just when conditions are right, and offer it only as an example of when freq coordination doesn't matter. Not complaining about the ant reception, just the CC issue.

 

[STiMULi]

Its just a Wilson 800 MHz Yagi at 25' AGL fed with LMR-400. I'm happy with it. Bear in mind that I cannot 'normally' hear them, just when conditions are right, and offer it only as an example of when freq coordination doesn't matter. Not complaining about the ant reception, just the CC issue.

Can you set up 2 different systems and use attenuation?

 

[blueline_308]

Atentuation wont work because if I attenuate the offending site, it will only attenuate when its on that site, not when it's CC is being recieved by the other site. I think thats how it works. But, thanks for the ideas...I need all the help I can get.

Jim

 

[wolter]

Jim,

One thing that would aid UPMan or others in helping you is to tell us what kind of scanner you have. Thanks!

All Uniden scanners that have CCh Only capability use the CCh data in the same way. So, it doesn't really matter which scanner he was using.

 

[blueline_308]

So am I the only one experiencing this issue?

 

[slicerwizard]

So am I the only one experiencing this issue?

Anyone who sits between two sites that share frequencies will experience this problem. This is no different than DXing AM stations at night - many will pile on top of each other.

Normally, your scanner would detect the end code which is transmitted at the end of each voice comm, and use that to force a return to the correct control channel, but the interfering signal is preventing that.

CC decoding logic isn't active when on a voive channel; instead, the end code detect logic comes in to play.

The bogus TGID you see is probably due to poor decoding of system A's control channel.

 

[loumaag]

As Slicerwizard says, this would be a problem for anyone with close by systems sharing frequencies. Make sure you have programed the radio to detect the end code, not ignore it. When you ignore the end code it is like being is CSQ mode, it waits for the squelch to close before returning to the CCh for further scanning. Since the CCh data stream from the other system/site is on the channel, then the squelch can't close and you stay there.

 

[blueline_308]

Well all that makes sense. but I do have end code detect enabled, and it doesn't seem to help at all. I suppose this is a peril of DXing trunk systems

It just seems too easy for the radio to sense when a voice transmission changes to data, then mute & resume, for it not to work that way.

Thanks for all the input and I wish a Uniden rep would jump in and tell us if thats something that could be added in a firmware update or add some more light on the matter.

73,
Jim

 

[wolter]

As Slicerwizard says, this would be a problem for anyone with close by systems sharing frequencies.

If this was true, the actual users of these systems would also have the problem. They don't.

 

[blueline_308]

I have to agree with 'wolter'. If I observe this with an antenna 25' AGL, and a non-government grade reciever, those systems sitting 100 or more feet must be observing it as well, but must have some way of sorting it out. I know of 2 sites, 70 miles apart, both public safety that on some days share the same CCh..

73,
Jim

 

[slicerwizard]

If this was true, the actual users of these systems would also have the problem. They don't.

Oh please. System users don't sit between two distant sites and try to work one of those sites; they affiliate to a local site instead. Unlike scannerheads, they drag comms of interest to a local site; they don't play the DX game.

 

[slicerwizard]

I know of 2 sites, 70 miles apart, both public safety that on some days share the same CCh..

And if a subscriber unit is 30 miles from its system, or on the wrong side of a hill, it WILL have problems. There is no magic bullet. This is why Motorola added the 2618 "Wrong system" deaffiliation OSW to their protocol.