Carrier with no audio on LTR

[n4yek]

I have a local LTR system I monitor. It is a new system and my experience with LTR trunking is just this side of stupid.
Here is the system before I get started:
http://www.radioreference.com/module...me=RR&sid=5373
The normal Sheriff talkgroup is 0-11-140, 99 percent of traffic is heard
normally. But periodically a talkgroup of 0-02-227 keys up on the
sheriff home channel on 11, no audio is transmitted, but it 'holds' the repeater up.
One time I was listening, and just as a sheriff deputy keyed up and spoke,
it showed the normal id of 0-11-140 then instantly switched
to 0-02-227 with just the carrier.
Any Ideas on what is happening here?
The scanner isn't trying to switch to any other repeater,
it just sits there with that ID until the carrier gets dropped.
I know they are still having conversation, because the dispatcher will
sometimes reply with '10-4'.
Is the LTR system sending the officer to an 'unknown' frequency or is
this some type of scrambling?
Thanks in advance,
Danny N4YEK

[kwrxxx]

Most likely this is a patch that allows the dispatcher to hear the input from the repeater, but the audio is not repeated through the LTR system.

[BC_Scan]

first of all what I see here is a bit of an unprobable, any id with o2 should not exist acording to the lcn chart
ids with 11 & 14 & 15 etc should only show , there is no 2 lcn that you have programmed into your scanner (according to what this site shows )
while I appreciate that your eyes are not deceiving you and that you read a 2-227 id , it does not jive with the way ltr works
my experience is that id's will show up with no ryme or reason that are part of the system (not assigned to any one) possibly part of the refresher pulse you hear on the channel when listening in conventional mode.
unkown freq or scrambler I doubt, but the question I have is the freq you have there all verified and scanning in ltr mode with your scanner. (in other words can you scan the system and hear properly all conversations regardless of talkgroup ?) if you are 100 percent sure there is carrier and no voice whatsoever than I would simply l/o that talk group

[wayne_h]

What are you using to track the system? It seems like it's misinterpreting the LTR data.

[n4yek]

I use a BC 780xlt, and I know the listing does not show LCN 2 on the
chart. But I have a theory on this concerning an e-mail I received from
someone one time concerning the new system. I inquired about the
LCN from the company that installed it once, never got a reply from
them but I received an email from someone I don't know with this
information:

Here is the trunk system to the best of my knowledge. I know this is public knowledge but if you dont mind keep where you got these between me and you.

464.150
464.600
464.450
461.625
462.125
451.350
464.4125
464.6875
460.025
451.075
453.875
460.625
453.3875
That's the list in order.

Now I didn't pay much attention to it since I didn't know this person, but when I found out that the company that installed the County LTR
system has one list under their own company name which is this:
http://www.radioreference.com/module...me=RR&sid=5483
This listing was just recently added to the database.
Now if you look closely, you will see that the LCN's match with the
e-mail I received months ago. I kinda put 2 and 2 together and
came up with a theory that both systems are possibly one big
system, with the County Governement using the upper LCN's and the
other local businesses using the lower lcn's. There are motels and
taxi cabs and tow trucks using the Land Air system.
Now here is the Kicker, WHEN the Sheriff LCN appears with the
ID of 0-02-227, you can go to 464.600, which I programmed into
LCN 2 according to the e-mail I received, and you ALSO see the
is 0-02-227 Simultaniously on LCN2. It stays there just as long as
the ID stays on LCN 11. When LCN 11 drops the carrier, so does
LCN 2.
This is why I think both the County and Land Air system is actually
One Bigs System, split into two.
Any thought from you?
Thanks for your replys.

[DaveNF2G]

Originally Posted by n4yek

Here is the trunk system to the best of my knowledge. I know this is public knowledge but if you dont mind keep where you got these between me and you.

You and him and the thousands of RadioReference forum users.

(If you were just kidding and omitted your smiley, then I apologize.)

[n4yek]

omited

[wayne_h]

There seems to be a problem with equipment somewhere. The SO doesn't seem to notice it so the 780 may be misinterpreting the low-speed data. With LTR each voice channel has its own controller so it's not like all of those freqs are sharing the same controller. And they cannot be interconnected (to permit trunk-offs/channel sharing) as that would violate FCC rules. But hey, ya never know.

[EricCottrell]

Originally Posted by n4yek

I use a BC 780xlt, and I know the listing does not show LCN 2 on the
chart. But I have a theory on this concerning an e-mail I received from
someone one time concerning the new system. I inquired about the
LCN from the company that installed it once, never got a reply from
them but I received an email from someone I don't know with this
information:

Here is the trunk system to the best of my knowledge. I know this is public knowledge but if you dont mind keep where you got these between me and you.

464.150
464.600
464.450
461.625
462.125
451.350
464.4125
464.6875
460.025
451.075
453.875
460.625
453.3875
That's the list in order.

Now I didn't pay much attention to it since I didn't know this person, but when I found out that the company that installed the County LTR
system has one list under their own company name which is this:
http://www.radioreference.com/module...me=RR&sid=5483
This listing was just recently added to the database.
Now if you look closely, you will see that the LCN's match with the
e-mail I received months ago. I kinda put 2 and 2 together and
came up with a theory that both systems are possibly one big
system, with the County Governement using the upper LCN's and the
other local businesses using the lower lcn's. There are motels and
taxi cabs and tow trucks using the Land Air system.
Now here is the Kicker, WHEN the Sheriff LCN appears with the
ID of 0-02-227, you can go to 464.600, which I programmed into
LCN 2 according to the e-mail I received, and you ALSO see the
is 0-02-227 Simultaniously on LCN2. It stays there just as long as
the ID stays on LCN 11. When LCN 11 drops the carrier, so does
LCN 2.
This is why I think both the County and Land Air system is actually
One Bigs System, split into two.
Any thought from you?
Thanks for your replys.

Hello,

When the 0-02-227 is directed to repeater 11 then it will appear on repeater 11 and also on repeater 2 directing the group to repeater 11. On the 780 if you hold on channel 2 then you should see two or more group ids. 227 is a high enough group that it could be a phone patch or other special purpose group.

If you program a LTR system with both repeater 2 and repeater 11 you can notice if this group is directed to repeater 11. The frequency has to be programmed in 11 for the 780 to go there.

The repeater numbers in the database entry for the county seem to suggest that it is part of a bigger system. I have seen a system down in RI setup like this where a user is licensed on a couple of frequencies and they only use those frequencies in the LTR system. Other users use other frequencies.

I suspect that this system maybe a LTR-Net or similar advanced system since it has multiple sites, The county talkgroups likely have priority for Repeater 11 so the 0-02-227 group is kicked off when they key up.

73 Eric

[n4yek]

Originally Posted by EricCottrell

Hello,

........
I suspect that this system maybe a LTR-Net or similar advanced system since it has multiple sites, The county talkgroups likely have priority for Repeater 11 so the 0-02-227 group is kicked off when they key up.

73 Eric

Thanks all to have helped,
The County talkgroup does not get kicked off, so I am not sure what is
going on with the system. It is possible it is LTRi-net, but like I have
stated, I am not on the up and up with LTR systems.
I am NOT the only one that does see the ID so I am sure its not my
radio.
Thanks again to all of you for your continued input, I like to see what
others have to say about the possibilities of what the system is doing.
I can tell you one thing, we have 4 law enforcement agencies in this
county, 3 cities and the Sheriff.
So far, 2 cities have said They are NOT going to go to the trunk
system because of issues of some type. The other city I don't know
anything, if they will or not.
Take care my friends

[DaveH]

Originally Posted by n4yek

Thanks all to have helped,

It is possible it is LTRi-net, but like I have
stated, I am not on the up and up with LTR systems.

What is the idle-channel pulse rate? For LTR-net it is
8 pulses per 10 seconds or 1.25s interval. Regular LTR
could be anything between 5s to 11s.

Dave

[pro92b]

There are a number of vendors selling enhancements to LTR systems. See for example http://mrtmag.com/mag/radio_poor_mans_multisite/ especially the reference to Net-Link at the bottom. See also http://www.idaco.com/Rayel.pdf

Has there been any press release about the new system that might identify who the equipment was bought from? If not, that information should be public record if you make a few calls.

[slicerwizard]

Originally Posted by EricCottrell

The county talkgroups likely have priority for Repeater 11 so the 0-02-227 group is kicked off when they key up.

How do you kick off an 02-227 subscriber radio that is transmitting on LCN 11?

[tennesseefreq]

The radios used on the system are Kenwood TK-8180s and TK-3180s

[n4yek]

I don't know the pulse rates, as DaveH has asked.
Land Air Communications is the dealer who sold the system to the county.
The also have a system listed to them in the database here as previously
mentioned above.
Again thanks for the input people.