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Question about system ID data (Legacy trunked systems)

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#1
I've been kind of curious about this for years but never put forth the effort to find out for myself.

So I'll ask now.

This question applies primarily to legacy Motorola trunked systems, that is, non-P25 systems.

It concerns the system identification information in the control channel data stream.

What information is actually transmitted as the system ID?

For example, take a given random Smartnet system which has (had) an ID of, say, 123A.

To program that system into a Motorola trunked system you'd need a system key for system 123A.

But wait....there is (was) a feature called "system aliasing" which, as I recall, instructed the radio to only pay attention to the (last, I think) half of the system ID. So the radio would think it's authorized for
systems 123A, 233A, 8D3A, whatever, as long as it ended in 3A.

Or perhaps it was the first two digits instead. I really don't recall with 100 percent certainty.

So what I'm curious about is what system ID information is actually in that control channel.

Since it's most likely that people who can look right at the raw data coming out of the control channel are visiting this subforum, I figured this was the place to ask.

I am also curious, and am asking what is fundamentally the same question, with regard to P25 systems
of both the Motorola and Harris flavors.

Harris did not originally implement system key access control in their radios. I think they do now, at least
as an option. Which makes me wonder how an agency with P25 Motorola radios can get their radios
programmed onto a Harris system that never originally was set up for system key usage.

And, finally, same question again, only this time, with regard to any difference in CC system ID data between systems that use legacy system keys and systems that use the ASK, Advanced System Key.
 
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#2
What information is actually transmitted as the system ID?
...
So what I'm curious about is what system ID information is actually in that control channel.
...
And, finally, same question again, only this time, with regard to any difference in CC system ID data between systems that use legacy system keys and systems that use the ASK, Advanced System Key.
The system ID is transmitted. Nothing more, nothing less.

The systems don't use keys. Radios don't use keys. RSS/CPS uses keys.
 
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#3
OK, but I request just a little bit more data.

For example, is the system ID transmitted as exactly "123A" in the case of system 123A or are there more bits in that part of the signalling sequence?

To take another look at one of my questions, is the system ID formatted any differently in a Harris vs. a Motorola P25 system?

Let's get really hypothetical here: Harris creates a new P25 system and its system ID just happens to be 123A. I have a Motorola system key from years past which is for a system 123A. So....I have access?
I'm guessing I do.

But I note that P25 systems have a 3 digit hex ID. Like 12A. Or at least that's what I'm seeing in the ones I've looked at in the database.

That makes me wonder, if I had a key 012A, would that work on a system identified as 12A?

I don't expect you to know that for sure. I'm just speculating.



I am aware that systems don't use keys. Keys are only programming side access control to prevent unauthorized programming of radios onto the system.
 

SCPD

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#4
Elroy - this is speculation on my part - I don't think Harris and Motorola "system keys" are interchangeable. Each vendor does its own proprietary thing.
 

natedawg1604

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#5
Well I can offer an example from a 800 MHz Moto 100% Analog system (System ID=3B27) albeit with only one site. Here is an excerpt from the Unitrunker Decode log:

30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
00D0 G 18B Continuation 18B C35F G 00D0
0270 G 188 Continuation 188 2721 G 0270
0470 G 18C Continuation 18C 51C8 G 0470
05F0 G 099 Continuation 099 G 05F0
3B27 I 32B Scan Mark Sysid=3B27
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
00D0 G 18B Continuation 18B C35F G 00D0
0270 G 188 Continuation 188 2721 G 0270
0470 G 18C Continuation 18C 51C8 G 0470
05F0 G 099 Continuation 099 G 05F0
3B27 I 32B Scan Mark Sysid=3B27
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
00D0 G 18B Continuation 18B C35F G 00D0
0240 G 188 bad OSW with 3 bit errors ***
0470 G 18C Continuation 18C 51C8 G 0470
05F0 G 099 Continuation 099 G 05F0
3B27 I 32B Scan Mark Sysid=3B27
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
00D0 G 18B Continuation 18B C35F G 00D0
4E82 I 104 bad OSW with 6 bit errors ***
0470 G 18C Continuation 18C 51C8 G 0470
05F0 G 099 Continuation 099 G 05F0
3B27 I 32B Scan Mark Sysid=3B27
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
5AC0 G 3C0 System Status [2] = 1AC0
30A8 G 3C0 System is Type II or IIi 800 Connect Tone=116.13 Hz
Just for comparison, here is a decode log excerpt from a Moto UHF 3-site Astro System (System ID=8D34):

000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
4300 I 3BF Network Status [2] = 0300
8D34 G 091
079C G 320
620D I 30B NetInfo, Sys=8D34, Cell=<02>, Alt DChan=20D 0.0000, Band=OBT, Wide, Astro, Analog
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
4300 I 3BF Network Status [2] = 0300
8D34 G 0C2
079C G 320
623E I 30B NetInfo, Sys=8D34, Cell=<02>, Alt DChan=23E 0.0000, Band=OBT, Wide, Astro, Analog
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
4300 I 3BF Network Status [2] = 0300
8D34 G 04F
0B9C G 320
61CB G 30B NetInfo, Sys=8D34, Cell=<03>, uses DChan=1CB 0.0000, Band=OBT, Wide, Astro, Analog
1040 G 361 Site 2
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
3000 G 3C0 System is Type II VHF/UHF Connect Tone=105.88 Hz
4900 G 3C0 System Status [2] = 0900
6001 G 3BF Network Status [3] = 0001
3000 G 3BF Network Status Dispatch Timeout 0, Interconnect Timeout 0, Connect Tone 105.88
 
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#6
Elroy - this is speculation on my part - I don't think Harris and Motorola "system keys" are interchangeable. Each vendor does its own proprietary thing.
Oh, I'm sure that the system key FILES would not be usable with the other manufacturer's programming software. No doubt about that.

But if you were to just happen to have a Motorola system key that happens to just happen to match the system ID of a Harris system, then it would seem that you could program your Motorola radio to work on that Harris system. (Assuming everything in question is all P25 and the same phase.)
 
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#7
OK, but I request just a little bit more data.

For example, is the system ID transmitted as exactly "123A" in the case of system 123A or are there more bits in that part of the signalling sequence?
No, there is nothing else pertaining to the SysID, system keys, etc.


To take another look at one of my questions, is the system ID formatted any differently in a Harris vs. a Motorola P25 system?
No. They both follow the P25 standard.


Let's get really hypothetical here: Harris creates a new P25 system and its system ID just happens to be 123A. I have a Motorola system key from years past which is for a system 123A. So....I have access?
I'm guessing I do.
123A is not a valid P25 system ID, so I'll substitute 123. With that key present, your Motorola RSS/CPS will let you program a Motorola radio for use with SysID 123. How well the radio works depends on what vendor specific messages (like patch announcements) the system is broadcasting. This assumes (on my part) that the WACN ID is not part of what the system key controls access to.


But I note that P25 systems have a 3 digit hex ID. Like 12A. Or at least that's what I'm seeing in the ones I've looked at in the database.

That makes me wonder, if I had a key 012A, would that work on a system identified as 12A?

I don't expect you to know that for sure. I'm just speculating.

I am aware that systems don't use keys. Keys are only programming side access control to prevent unauthorized programming of radios onto the system.
I would assume that both the WACN ID and system ID are programmed into P25 radios and that the radio looks for a match on both, although there are roaming capabilities which means that there is more to it than that. For example, radios here will roam between system BEE00-3C2 and BEE00-64C, and probably some others. Not sure how much of that is due to radio programming or the fact that the systems point at each other through the neighbour lists that they broadcast.
 
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