Topics

LTR question


Evan Platt
 

So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)


Tom Crowley
 

LTR systems have no Data Channel, data is sent like a sub audible tone.
Radio's are assigned to a home channel, when you push the PTT you are requesting a open Ch and the system will tell all the radio's in your group to go to this Ch aka repeater.
I'll have to look at the Channel number if I remember correctly the number is sometime confuse with the Freq
The FCC set a group of 800 Mhz to Ch numbers and some documents would state the system is made up of Ch 20, 1, 34 and 16. Most system had 3, 5,7 or 10 repeaters.
I'll look at some info from EFJ

-----Original Message-----
From: main@Scanner.groups.io <main@Scanner.groups.io> On Behalf Of Evan Platt
Sent: Monday, June 01, 2020 9:04 PM
To: main@scanner.groups.io
Subject: [Scanner] LTR question

So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here that has almost no activity. So there's the say 6 channels, and some talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12, channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)


Joe M.
 

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this channel will be free and when they key up they will use it. If it is busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them) have no data channel.

LTR is a dying format. There are virtually no new systems coming on the air. Almost all new systems will be digital (P25, DMR, or NXDN for the most part).

You didn't describe "different home repeaters with the same channels" at all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short. When the home channel is busy, they try to spread the activity over all the system channels. They use what is called a Round Robin to do this. It's a pattern chose to pick the next channel selected. OK, a couple examples to demonstrate the logic (no pun intended, as LTR is Logic Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did). Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8. There is no 8, so it uses the next available channel: Channel 1. Next time, it picks 15. There is no 15 so it uses the next available channel: Channel 1. Next time it picks 20. There is no 20 so it uses the next available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly all the use because the odds it will pick channels 2/4/5 are 1 in 7. For each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN (your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)



Evan Platt
 

I remember back in the days of 800 mhz Motorola trunking, some radios
used "Channel #" instead of frequency - ie you'd have to convert
852.0125 to channel # - it might be channel 43, so then you program
your radio for "Channel 43" or something like that (been a while) but
that was only 800 mhz if I recall.

But so still - why have different talkgroups be different home
repeaters on the same system? and why the gap in channels?

Here's a good example around here:
https://www.radioreference.com/apps/db/?sid=450
# of talkgroups on home channel 02, 1 on 7, a bunch on 12, 1 on 14,
and a bunch on 17.

On Mon, Jun 1, 2020 at 8:06 PM Tom Crowley
<tecrowley@stansgargreenhouse.com> wrote:

LTR systems have no Data Channel, data is sent like a sub audible tone.
Radio's are assigned to a home channel, when you push the PTT you are requesting a open Ch and the system will tell all the radio's in your group to go to this Ch aka repeater.
I'll have to look at the Channel number if I remember correctly the number is sometime confuse with the Freq
The FCC set a group of 800 Mhz to Ch numbers and some documents would state the system is made up of Ch 20, 1, 34 and 16. Most system had 3, 5,7 or 10 repeaters.
I'll look at some info from EFJ

-----Original Message-----
From: main@Scanner.groups.io <main@Scanner.groups.io> On Behalf Of Evan Platt
Sent: Monday, June 01, 2020 9:04 PM
To: main@scanner.groups.io
Subject: [Scanner] LTR question

So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here that has almost no activity. So there's the say 6 channels, and some talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12, channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)







Joe M.
 

That is still true. Only now they include a bandplan along with the channel number. When the channel grant is made, they calculate the frequency based on those two pieces of info. A common bandplan #0 is:

Bandplan #0: Base=851.00625 Offset=-45 Spacing=6.25 BW=12.5
Bandplan #1: Base=762.00625 Offset=+30 Spacing=6.25 BW=12.5
Bandplan #2: Base=851.0125 Offset=-45 Spacing=12.5 BW=12.5 Slots=2
Bandplan #3: Base=762.00625 Offset=+30 Spacing=12.5 BW=12.5 Slots=2

That is actually standard on P25 systems. VHF/UHF systems add to that starting with bandplan #4.

The offset only affects the TX frequency. You know what BW is.

Let's say a grant is on BP0-CH137. The formula is:

FREQ = BASE+(Spacing x CH)
= 851.00625+(6.25kHz x 137)
= 851.00625+(856.25kHz)
= 851.86250 MHz

Joe M.

On 6/1/2020 11:19 PM, Evan Platt wrote:
I remember back in the days of 800 mhz Motorola trunking, some radios
used "Channel #" instead of frequency - ie you'd have to convert
852.0125 to channel # - it might be channel 43, so then you program
your radio for "Channel 43" or something like that (been a while) but
that was only 800 mhz if I recall.

But so still - why have different talkgroups be different home
repeaters on the same system? and why the gap in channels?

Here's a good example around here:
https://www.radioreference.com/apps/db/?sid=450
# of talkgroups on home channel 02, 1 on 7, a bunch on 12, 1 on 14,
and a bunch on 17.

On Mon, Jun 1, 2020 at 8:06 PM Tom Crowley
<tecrowley@stansgargreenhouse.com> wrote:

LTR systems have no Data Channel, data is sent like a sub audible tone.
Radio's are assigned to a home channel, when you push the PTT you are requesting a open Ch and the system will tell all the radio's in your group to go to this Ch aka repeater.
I'll have to look at the Channel number if I remember correctly the number is sometime confuse with the Freq
The FCC set a group of 800 Mhz to Ch numbers and some documents would state the system is made up of Ch 20, 1, 34 and 16. Most system had 3, 5,7 or 10 repeaters.
I'll look at some info from EFJ

-----Original Message-----
From: main@Scanner.groups.io <main@Scanner.groups.io> On Behalf Of Evan Platt
Sent: Monday, June 01, 2020 9:04 PM
To: main@scanner.groups.io
Subject: [Scanner] LTR question

So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here that has almost no activity. So there's the say 6 channels, and some talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12, channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)








Evan Platt
 

Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)





Joe M.
 

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.

On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)






Jeff Kenyon
 

Does anyone know of specific users of the E.F Johnson P-25 that is different? The other format that has its days numbered is OpenSky. I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system. The MPSCS which is the statewide system in Michigan is only P-25 Phase I. I read this on the signalharber page that has a list of OpenSky systems across the country. I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.

On Jun 1, 2020, at 11:51 PM, Joe M. <mch@nb.net> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)







Evan Platt
 

I took a gamble a while back. Harris radio. As is. Turns out it was a
800 mhz analog / EDACS radio. Only 1 thing around here on EDACS. Was
able to program it fo rx only :-D Now that was a pain lol

On Mon, Jun 1, 2020 at 8:51 PM Joe M. <mch@nb.net> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not
all spread out more. A possible explanation is that back when they were
put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed
the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs
without reprogramming any radios (and use the vacated frequencies for
another system).

If you have all users home to LCN 12, then LCN 12 is going to get much
more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is
based on 20 channels. You would not want to have to change the firmware
every time you add an LCN. Yes, they could have improved the system, but
it's just as easy to program the radios when you add them. It's easier
in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria
- the one with the least up-time gets the assignment. It's a much better
solution, but LTR is LTR. There is also the fact that EF Johnson likes
their LTR scheme and even made some P25 systems based on LCN rather than
the bandplan (each bandplan = 1 frequency and only 1). These are called
implicit P25 systems and are pretty rare. They are limited to 16
frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR
scheme into their P25 systems. That gives you some idea of the mentality
of convincing them to change anything. Naturally, these P25 systems are
not fully compatible with all P25 radios (which was the ENTIRE POINT
behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS,
ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN,
and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)








Joe M.
 

Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different? The other format that has its days numbered is OpenSky. I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system. The MPSCS which is the statewide system in Michigan is only P-25 Phase I. I read this on the signalharber page that has a list of OpenSky systems across the country. I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@nb.net> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)









Mike Vander Veer
 

I believe even Vegas is at least in the process of dropping it.

And Jeff, there are a few threads on RadioReference about the switch to P25 Phase 2 in Oakland County.

Mike

On 6/2/2020 2:52 AM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different?  The other format that has its days numbered is OpenSky.  I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system.  The MPSCS which is the statewide system in Michigan is only P-25 Phase I.  I read this on the signalharber page that has a list of OpenSky systems across the country.  I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@...> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system  locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@...> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)























David Williams
 

Las Vegas has been using a Motorola Phase 2 system I think for a couple of years now. 


Dave

On Tue, Jun 2, 2020 at 9:40 AM Mike Vander Veer <mbvv@...> wrote:
I believe even Vegas is at least in the process of dropping it.

And Jeff, there are a few threads on RadioReference about the switch to P25 Phase 2 in Oakland County.

Mike

On 6/2/2020 2:52 AM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different?  The other format that has its days numbered is OpenSky.  I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system.  The MPSCS which is the statewide system in Michigan is only P-25 Phase I.  I read this on the signalharber page that has a list of OpenSky systems across the country.  I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@...> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system  locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@...> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)






















--


Joe M.
 

Not surprised. That would leave no OS systems.

Joe M.

On 6/2/2020 9:40 AM, Mike Vander Veer wrote:
I believe even Vegas is at least in the process of dropping it.

And Jeff, there are a few threads on RadioReference about the switch to
P25 Phase 2 in Oakland County.

Mike

On 6/2/2020 2:52 AM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think
only two plan to keep using it - Vegas and Oakland, MI. Well, based on
your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is
different? The other format that has its days numbered is OpenSky.
I read some place that Oakland County, Michigan who currently has
OpenSky actually signed a contract with Motorola to build a P-25
Phase II system that will at some point be intograted into the state
wide system. The MPSCS which is the statewide system in Michigan is
only P-25 Phase I. I read this on the signalharber page that has a
list of OpenSky systems across the country. I’m really surprised
that nothing has been said on radioreference about the current
Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@nb.net> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they
not all spread out more. A possible explanation is that back when
they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and
reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs
without reprogramming any radios (and use the vacated frequencies
for another system).

If you have all users home to LCN 12, then LCN 12 is going to get
much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin)
is based on 20 channels. You would not want to have to change the
firmware every time you add an LCN. Yes, they could have improved
the system, but it's just as easy to program the radios when you add
them. It's easier in the firmware to just move up the the first
non-busy LCN.

But newer systems will use the actual TX time as the selection
criteria - the one with the least up-time gets the assignment. It's
a much better solution, but LTR is LTR. There is also the fact that
EF Johnson likes their LTR scheme and even made some P25 systems
based on LCN rather than the bandplan (each bandplan = 1 frequency
and only 1). These are called implicit P25 systems and are pretty
rare. They are limited to 16 frequencies maximum I think. So EFJ
just HAD to "Frankenstein" their LTR scheme into their P25 systems.
That gives you some idea of the mentality of convincing them to
change anything. Naturally, these P25 systems are not fully
compatible with all P25 radios (which was the ENTIRE POINT behind
P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS,
ProVoice, ..... well, let's face it - everything except P25, DMR,
NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that
support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of
them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming
on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for
the
most part).

You didn't describe "different home repeaters with the same
channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity
over all
the system channels. They use what is called a Round Robin to do
this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin
picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available
channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get
nearly
all the use because the odds it will pick channels 2/4/5 are 1 in
7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is
busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on
the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here
would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them
1, 2,
3 and 4?

Thanks :)











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Jeff Kenyon
 

The one in Vegas was replaced with a P-25 system, and police are all encrypted. When Oakland County, Mi announced they would be going OpenSky in 2002 it was a shock to everyone. It wasn’t until 2010 and lots of $$$ later that it was finally finished. Since they moved over I have no idea on how people like the system. One incident that comes to mind where they could have been on a system with interoperability with the rest of the area happened a while ago where a lady jumped into a police car when the officer was out talking to someone and took a joyride into Detroit. Multiple departments were involved of course, and I don’t know how communications with Detroit PD/FD who are on Michigan’s System was handled.

On Jun 2, 2020, at 2:53 AM, Joe M. <mch@nb.net> wrote:

Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different? The other format that has its days numbered is OpenSky. I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system. The MPSCS which is the statewide system in Michigan is only P-25 Phase I. I read this on the signalharber page that has a list of OpenSky systems across the country. I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@nb.net> wrote:
Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@nb.net> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)










Septa3371CSX1
 

Vegas ditched their Open Scam system and went with a P25 Phase II system.  The Commonwealth of Pennsylvania is in the process of deploying a multi-band P25 Phase II system to replace the problem-plauged Open Scam system.  The new system is on track to be fully deployed across PA by 2021.

Erie County, PA recently deployed a UHF P25 Phase II system that was built by EFJ.  I live way in the other corner of PA so I can't say how that system works but that's one example.
th
Getting back to LTR systems, quite a few in my area have converted to DMR and NXDN in recent years.  There are still a few SMR's in the area using LTR and the LCN's are kinda random.  

Joe Butler


-----Original Message-----
From: Joe M. <mch@...>
To: main@Scanner.groups.io
Sent: Tue, Jun 2, 2020 2:52 am
Subject: Re: [Scanner] LTR question

Open Sky was DOA almost before release. Many have tried it. I think only
two plan to keep using it - Vegas and Oakland, MI. Well, based on your
info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
> Does anyone know of specific users of the E.F Johnson P-25 that is different?  The other format that has its days numbered is OpenSky.  I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system.  The MPSCS which is the statewide system in Michigan is only P-25 Phase I.  I read this on the signalharber page that has a list of OpenSky systems across the country.  I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
>> On Jun 1, 2020, at 11:51 PM, Joe M. <mch@...> wrote:
>>
>> Busy system (LCN-wise).
>>
>> 0 is the Area Code. (not used on the cast majority) It can be 0 or 1.
>>
>> Your understanding of Home and TG is correct.
>>
>> Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).
>>
>> As they added channel capacity, they never went back and reprogrammed the user radios.
>>
>> Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).
>>
>> If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.
>>
>> The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.
>>
>> But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)
>>
>> Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.
>>
>> Joe M.
>>
>>
>>> On 6/1/2020 11:35 PM, Evan Platt wrote:
>>> Thanks for the response, that helps..
>>>
>>> So here's one system  locally:
>>> https://www.radioreference.com/apps/db/?sid=450
>>> So my understanding is (Please tell me this is right otherwise I've
>>> been programming radios wrong LOL).. So talkgroup
>>> 0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
>>> talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
>>> on 12, some on 17. Is there some advantage or disadvantage or reason
>>> they aren't all on home channel 12?
>>>
>>> If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
>>> know that there is no 6,7, 8, 9, etc?
>>> So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
>>> radios around, and not many LTR systems around... A dying breed, kind
>>> of like Motorola Type II trunking and EDACS :-D
>>>
>>>> On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@...> wrote:
>>>>
>>>> How is it not scanner related? There are many scanners that support LTR.
>>>>
>>>> LTR works by each user group having a Home Channel. Ideally, this
>>>> channel will be free and when they key up they will use it. If it is
>>>> busy they are sent to another channel.
>>>>
>>>> The Home Channel is not a data channel. LTR systems (well, most of them)
>>>> have no data channel.
>>>>
>>>> LTR is a dying format. There are virtually no new systems coming on the
>>>> air. Almost all new systems will be digital (P25, DMR, or NXDN for the
>>>> most part).
>>>>
>>>> You didn't describe "different home repeaters with the same channels" at
>>>> all. Maybe you can clarify what you are asking.
>>>>
>>>> Why skip channels? Well, it's a long story I will try to make short.
>>>> When the home channel is busy, they try to spread the activity over all
>>>> the system channels. They use what is called a Round Robin to do this.
>>>> It's a pattern chose to pick the next channel selected. OK, a couple
>>>> examples to demonstrate the logic (no pun intended, as LTR is Logic
>>>> Trunked Radio):
>>>>
>>>> 1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
>>>> Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
>>>> There is no 8, so it uses the next available channel: Channel 1. Next
>>>> time, it picks 15. There is no 15 so it uses the next available channel:
>>>> Channel 1. Next time it picks 20. There is no 20 so it uses the next
>>>> available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
>>>> all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
>>>> each one time it picks 2/4/5, it will use channel 1 SIX times.
>>>>
>>>> 2. Let's come up with a way to even out the channel use. You have the
>>>> same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
>>>> (your home of 9) is busy, let's use the exact same picks as above:
>>>>
>>>> Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
>>>> Round Robin 15 uses channel 17
>>>> Round Robin 20 uses channel 1
>>>>
>>>> See how that evens out the use of each LCN? That evens out wear on the
>>>> transmitters and does not stress LCN 1 more than the others.
>>>>
>>>> Joe M.
>>>>
>>>> On 6/1/2020 10:04 PM, Evan Platt wrote:
>>>>> So not technically 'scanner' related, but figured someone here would know..
>>>>>
>>>>> How does LTR trunking work?
>>>>> (Not a lot of LTR around here).
>>>>> Is "Home repeater" a data channel? There's a local LTR system here
>>>>> that has almost no activity. So there's the say 6 channels, and some
>>>>> talkgroups use home repeater 1, some use 4, etc. So questions:
>>>>>
>>>>> Why have different home repeaters with the same channels? Is there
>>>>> some logic behind that?
>>>>>
>>>>> And why 'skip' channels? If you have 4 channels, for the LCN, why
>>>>> aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
>>>>> channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
>>>>> 3 and 4?
>>>>>
>>>>> Thanks :)
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
>
>
>
>
>




Jeff Kenyon
 

Good, now we just need to pray that Oakland County doesn’t decide to encrypt everything.  The Vegas OpenSky system is gone as far as I know, and the P-25 is all encrypted as far as the police is concerned.


On Jun 2, 2020, at 9:40 AM, Mike Vander Veer <mbvv@...> wrote:

 I believe even Vegas is at least in the process of dropping it.

And Jeff, there are a few threads on RadioReference about the switch to P25 Phase 2 in Oakland County.

Mike

On 6/2/2020 2:52 AM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different?  The other format that has its days numbered is OpenSky.  I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system.  The MPSCS which is the statewide system in Michigan is only P-25 Phase I.  I read this on the signalharber page that has a list of OpenSky systems across the country.  I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@...> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system  locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@...> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)























Mike Vander Veer
 

The information I've heard has been 100% encryption.  I can't confirm that to be true, only conversations I've heard.

Mike

On 6/2/2020 9:42 AM, Jeff Kenyon wrote:
Good, now we just need to pray that Oakland County doesn’t decide to encrypt everything.  The Vegas OpenSky system is gone as far as I know, and the P-25 is all encrypted as far as the police is concerned.


On Jun 2, 2020, at 9:40 AM, Mike Vander Veer <mbvv@...> wrote:

 I believe even Vegas is at least in the process of dropping it.

And Jeff, there are a few threads on RadioReference about the switch to P25 Phase 2 in Oakland County.

Mike

On 6/2/2020 2:52 AM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.

On 6/2/2020 12:17 AM, Jeff Kenyon wrote:
Does anyone know of specific users of the E.F Johnson P-25 that is different?  The other format that has its days numbered is OpenSky.  I read some place that Oakland County, Michigan who currently has OpenSky actually signed a contract with Motorola to build a P-25 Phase II system that will at some point be intograted into the state wide system.  The MPSCS which is the statewide system in Michigan is only P-25 Phase I.  I read this on the signalharber page that has a list of OpenSky systems across the country.  I’m really surprised that nothing has been said on radioreference about the current Oakland County OpenSky System.
On Jun 1, 2020, at 11:51 PM, Joe M. <mch@...> wrote:

Busy system (LCN-wise).

0 is the Area Code. (not used on the cast majority) It can be 0 or 1.

Your understanding of Home and TG is correct.

Why are they not all on LCN 12? The better question is why are they not all spread out more. A possible explanation is that back when they were put on the system, they only had LCNs 2/12/17 (and likely 7).

As they added channel capacity, they never went back and reprogrammed the user radios.

Maybe they are thinking that they can still reduce it to 3 or 4 LCNs without reprogramming any radios (and use the vacated frequencies for another system).

If you have all users home to LCN 12, then LCN 12 is going to get much more use than any other LCN.

The firmware is based on 20 channels. The randomizer (Round Robin) is based on 20 channels. You would not want to have to change the firmware every time you add an LCN. Yes, they could have improved the system, but it's just as easy to program the radios when you add them. It's easier in the firmware to just move up the the first non-busy LCN.

But newer systems will use the actual TX time as the selection criteria - the one with the least up-time gets the assignment. It's a much better solution, but LTR is LTR. There is also the fact that EF Johnson likes their LTR scheme and even made some P25 systems based on LCN rather than the bandplan (each bandplan = 1 frequency and only 1). These are called implicit P25 systems and are pretty rare. They are limited to 16 frequencies maximum I think. So EFJ just HAD to "Frankenstein" their LTR scheme into their P25 systems. That gives you some idea of the mentality of convincing them to change anything. Naturally, these P25 systems are not fully compatible with all P25 radios (which was the ENTIRE POINT behind P25!!!)

Dying standards: LTR, Motorola Type II, Motorola Type I, EDACS, ProVoice, ..... well, let's face it - everything except P25, DMR, NXDN, and TETRA. Even P25 Phase I has its days numbered.

Joe M.


On 6/1/2020 11:35 PM, Evan Platt wrote:
Thanks for the response, that helps..

So here's one system  locally:
https://www.radioreference.com/apps/db/?sid=450
So my understanding is (Please tell me this is right otherwise I've
been programming radios wrong LOL).. So talkgroup
0-02-016 - I forgot what the 0 is. 02 is the homechannel. 16 is the
talkgroup ID. So this system has a bunch of talkgroups on HC 2, some
on 12, some on 17. Is there some advantage or disadvantage or reason
they aren't all on home channel 12?

If the system uses channels 1,2,3 4 and 5, isn't it smart enough to
know that there is no 6,7, 8, 9, etc?
So I guess the answer is LTR isn't that smart? LOL. Yeah not many LTR
radios around, and not many LTR systems around... A dying breed, kind
of like Motorola Type II trunking and EDACS :-D

On Mon, Jun 1, 2020 at 8:21 PM Joe M. <mch@...> wrote:

How is it not scanner related? There are many scanners that support LTR.

LTR works by each user group having a Home Channel. Ideally, this
channel will be free and when they key up they will use it. If it is
busy they are sent to another channel.

The Home Channel is not a data channel. LTR systems (well, most of them)
have no data channel.

LTR is a dying format. There are virtually no new systems coming on the
air. Almost all new systems will be digital (P25, DMR, or NXDN for the
most part).

You didn't describe "different home repeaters with the same channels" at
all. Maybe you can clarify what you are asking.

Why skip channels? Well, it's a long story I will try to make short.
When the home channel is busy, they try to spread the activity over all
the system channels. They use what is called a Round Robin to do this.
It's a pattern chose to pick the next channel selected. OK, a couple
examples to demonstrate the logic (no pun intended, as LTR is Logic
Trunked Radio):

1. Your system uses channels 1/2/3/4/5 (as original LTR systems did).
Let's say your home channel is 3 and 3 is busy. The Round Robin picks 8.
There is no 8, so it uses the next available channel: Channel 1. Next
time, it picks 15. There is no 15 so it uses the next available channel:
Channel 1. Next time it picks 20. There is no 20 so it uses the next
available channel: Channel 1. SEE THE PROBLEM? Channel 1 will get nearly
all the use because the odds it will pick channels 2/4/5 are 1 in 7. For
each one time it picks 2/4/5, it will use channel 1 SIX times.

2. Let's come up with a way to even out the channel use. You have the
same 5-channel system, but using LCN 1/5/9/13/17. Now, if the 3rd LCN
(your home of 9) is busy, let's use the exact same picks as above:

Round Robin 8 uses channel 13 (remember - LCN 9 - your home - is busy).
Round Robin 15 uses channel 17
Round Robin 20 uses channel 1

See how that evens out the use of each LCN? That evens out wear on the
transmitters and does not stress LCN 1 more than the others.

Joe M.

On 6/1/2020 10:04 PM, Evan Platt wrote:
So not technically 'scanner' related, but figured someone here would know..

How does LTR trunking work?
(Not a lot of LTR around here).
Is "Home repeater" a data channel? There's a local LTR system here
that has almost no activity. So there's the say 6 channels, and some
talkgroups use home repeater 1, some use 4, etc. So questions:

Why have different home repeaters with the same channels? Is there
some logic behind that?

And why 'skip' channels? If you have 4 channels, for the LCN, why
aren't they channel 1, 2, 3 and 4? Why have channel 1, channel 12,
channel 18 and channel 21 (for the LCN)? Why not just make them 1, 2,
3 and 4?

Thanks :)
























Mike Derryberry
 

On 6/1/2020 11:52 PM, Joe M. wrote:
Open Sky was DOA almost before release. Many have tried it. I think only two plan to keep using it - Vegas and Oakland, MI. Well, based on your info make that only Vegas.

I guess 'what gets put on in Vegas stays on in Vegas'.

Joe M.
Vegas dumped their Open Sky system. It worked great in the Las Vegas city area but they never could get it to work in the outlying areas and mountains. They had to keep their old 150mhz system patched to the Open Sky system. After 5 years of messing around with and the Harris never able to get it to work correctly, Las Vegas went to Motorola and had them design and install a 700mhz P25 Phase 2 system and sued Harris to get their money back.

Mike

miked911@pacbell.net
Mike Derryberry

Dispatcher II
Kern County Sheriff's Department
Bakersfield, CA


Listen to Kern County Scanning:
http://energy10.egihosting.com:3070/listen.pls

Listen to Central California Fire Scanning
http://energy10.egihosting.com:3072/listen.pls


WB6EGR Las Vegas
 

The Las Vegas Open Sky system NEVER worked correctly anywhere in Las Vegas! the problem is Opensky cant use simulcast, each site is a master site. Each radio has a IP and requires a constant connection. Lose the IP, lose the voice encode. Mobiles were bad, portables were HORRIBLE. Forget about a footchase, you were on your own.Portables eat batterys in less than a 8 hour shift, mobiles ran so hot you could warm up your lunch on them. The radios had to constantly "handshake" to keep their "Connection".Field officers were VERY concerned they could not call for a backup. The same exact hardware flashed for P25 works very well. LVMPD went to the Motorola APX mobiles and portables. The entire system is on 700Mhz at it's own site.Rumor has it...they shipped it all back....in Waste Management trucks.... as it certainly was garbage.


On Tue, Jun 2, 2020 at 5:52 PM Mike Derryberry <miked911@...> wrote:
On 6/1/2020 11:52 PM, Joe M. wrote:
> Open Sky was DOA almost before release. Many have tried it. I think
> only two plan to keep using it - Vegas and Oakland, MI. Well, based on
> your info make that only Vegas.
>
> I guess 'what gets put on in Vegas stays on in Vegas'.
>
> Joe M.
>

Vegas dumped their Open Sky system. It worked great in the Las Vegas
city area but they never could get it to work in the outlying areas and
mountains. They had to keep their old 150mhz system patched to the Open
Sky system. After 5 years of messing around with and the Harris never
able to get it to work correctly, Las Vegas went to Motorola and had
them design and install a 700mhz P25 Phase 2 system and sued Harris to
get their money back.

Mike

miked911@...
Mike Derryberry

Dispatcher II
Kern County Sheriff's Department
Bakersfield, CA


Listen to Kern County Scanning:
http://energy10.egihosting.com:3070/listen.pls

Listen to Central California Fire Scanning
http://energy10.egihosting.com:3072/listen.pls





Evan Platt
 

So question on programming a two way radio with LTR if anyone here
knows - I take it home channel acts as like a data channel - so to
speak?

Here's the 'problem' - Every LTR HT I've had has you program the
channels in LCN, and tag the Home Channel, And most HT's, you can only
have one system per Zone. Since I'm basically using the HT as a
scanner, it's kind of a pain to have to set up a zone for each home
channel. Say there's 3 companies on home channel 2 and 4 companies on
home channel 4. If I'm JUST using the HT to receive, will it still
'work' to monitor if I put the talkgroup in but it's the wrong home
channel?

Hope this makes sense :) Thanks!