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Alright, I'm sorry if this is a dumb question. I'm interested in learning more about trunked systems, but my current knowledge is woeful, and I don't have a trunked system to play on. (And really, I don't even have much in the way of trunked systems to monitor.)
What I'm wondering about today is PTT-ID in trunked systems. I understand that the radios have their own IDs on the network, but I've never heard of them being used as a PTT-ID. Are they, or do people still resort to something like MDC-1200 for ID? And if they're using the actual trunking data as a PTT-ID, are there any radios that can decode it in the field?
Thanks for always answering my dumb questions.
Edit: I didn't specify in the main post... I'm wondering about trunking in general, not any particular type. Being a Motorola-related forum, I'm of course predominantly interested in SmartZone / Smartnet systems, but I'm all ears about EDACS/LTR too.
PTT-ID is exactly that, the six digit id of the radio. Many radios decode the id(especially digital) and the number can be aliased to a real name such as EMS 5 or similar. Problem is keeping the aliases up to date.
The id is teansmitted every time the radio is keyed and is used by the system as well as the end user if needed.
To recap a bit PTTID exists on non-trunked systems using various in-band sgnalling schemes (MDC1200, Astro/P25, Selcall, 5-Tone etc). A decoder in the receiving terminal looks at the signalling and presents the ID or an alias to the ID.
On a trunked system, there are two opportunities for PTT-ID : On the control channel or on the traffic channel. On the control channel (Astro/P25, MPT1327, LTR etc) there is some signalling which indicates the calling ID and the called ID or called talk group. These IDs are known by the trunked system in some way. The receiving terminal has to be able to decode them in order to decide whether to go to the designated traffic channel for the call. (ie is it addressed to me or a group that I belong to). Scanners usually decode this info aswell.
On the traffic channel, the calling terminal is required to pass its ID (P25) or may pass an ID using a convention (anything else). It usually doesn't make much sense on the FM traffic channels to have additional signalling overhead so I expect that only the control channel ID data is decoded.
The following link may or may not have what you are looking for, but nevertheless should provide some very good reading if you are interested in how Motorola trunking systems work.
I wrote this up a long time ago. may be appropiate here.
The 6 Digit ID
An explanation for the use of the six digits ID as used on the 800 MHz Radio system.
The six digits ID is the main controlling factor on ALL Trunked radios. The six digit ID must be programmed in three separate areas of the Trunked Radio System for proper operation on the individual radio and for various features to function:
The Central Site Controller (CSC) (at the tower site)
The individual Radio
The Console Electronics Bank (CEB) (at Police Dispatch Center)
The Individual six digit ID MUST be the same at each location for the radio to function properly, proper Alias display, and have the proper features enabled.
There are several restrictions that are placed on the six digits ID usage, and several internal conventions that we follow.
All ID’s are six digit Decimal numeric units, or four digit hexadecimal unit equivalents.
(Note) For the remainder of these instructions, we will use the six digit decimal unit.
The First digit indicates either an individual ID or a Talk Group ID, For example
8 = Talk group 800003 = 1A-PDISP
7 = Individual 701100 = TS-P-315
(Note) From here we will focus on the Individual six digit ID.
The Second digit is always “0”, It should be noted that the first two digits “70” are not used when converting a decimal ID to a hexadecimal format.
6 Digit Drop 70 Hex
701100 = 1100 = 044C You can use the Windows Calculator to convert ID’s.
The third digit indicates the type of equipment or function.
“0” = Console ID 700003 = CON-OP-1 Console Operator 1
“1” = Portable ID 701001 = TS-P-315 Traffic Portable 315
“2” = Mobile ID 702312 = TS-M-304 Traffic Mobile 304
“3” = Base ID 703003 = FD-STA-2 Fire Station 2 Base
“4” = Transit Bus ID 704002 = WT-M-002 Transit Bus 2
“5” = Siren ID 705002 = SIREN-2 Siren at Location 2
The fourth, fifth, and last digits identify the individual radio, and must be unique for each type of equipment. Only one individual ID can be used per unit, and no ID can be duplicated.
701100 = TS-P-315 assigned to Traffic Services Portable unit 315
(Note) At no time can any ID be duplicated.
At the Central Site Controller (CSC) tower Site; the six digits ID controls the following functions:
·Allows radio access to the system. If the ID is disabled in the CSC the radio cannot transmit.
·Indicates whether the radio is a fixed or mobile unit.
·Sets the priority level of the radio. For the City of Waco’s system, Priority levels are set in the Talk groups.
Priority 1 = Emergency Button
Priority 2 = All PD, County, and Fire Channels Including Siren and EAS channels
Priority 8 = All other City of Waco Channels
·Sets the ability for System wide access. No radio on the City of Waco’s system has this privilege.
·Sets the ability to make a MultiGroup Call (All Call)
·Sets the ability to make a Private Call, This feature has been disabled.
·Sets the ability to use Dynamic Regrouping, This feature is available but not implemented.
·Sets the ability to make a Paging call.
·Sets the ability to make a Secure call.
(Note) Some of these features may require additional programming or hardware in the individual’s radio.
In the Individual Radio the ID performs the following functions:
·Identifies the radio to the system as an individual unit.
·Each time one of the following functions is performed, the individual radio transmits its ID. Turn-On, Turn-Off, PTT, Channel Change, Emergency Button Press, Special Call placed.
·All ID’s are Logged and the function indicated at the CSC, Site Lens computer, System Watch Computer, and Dispatcher console.
At the Dispatch Console the ID performs the following function:
·Displays an “Alias” on the console to allow easy identification of the individual radio.
·The Alias is used to Identify Individuals for Emergency transmissions.
Aliasing is the process of linking the six digits ID to an alphanumeric text file, for display on the Dispatch consoles, and Site Lens computer. This alphanumeric text will identify the individual radio to the best extent possible. Additional Information for individual radios is maintained in a master radio inventory.
The rules for Aliases:
1. No duplicate Aliases are allowed
2. No more than eight characters per Alias. (Current displays only have 8 segments) See Note below.
3. All Capital letters. (Easier to distinguish on display)
4. Dashes used to separate identifiers. (If character count allows)
5. Alias will be assigned to a unit or badge number when ever possible. (Without duplication).
The first character set of the Alias identifies the department.
TS = Traffic Services
PS = Police Services
SO = Sheriff Office
US = Utility Service
The Center character of the Alias identifies the type of equipment.
TS-P = Traffic Services Portable
PS-M = Police Services Mobile
US-C = UtilitiesBase Radio
The last character set of the Alias identifies the individual radio or unit.
TS-P-315 = Traffic Services Portable unit 315.
PS-M-003 = Police Services Mobile radio installed in vehicle 003
FD-STA-2 = Fire Station 2 Base Radio.
(Note) With the upgrade to the WPD and Fire Dispatch consoles, the Alias will be extended to 16 characters for display on the computer monitor.
Alias Database maintenance.
(Note) Radio Alias’s are linked to the radio’s six digit ID’s through the Alias Data Base Manager in the CEB at the Police department.
It should be pointed out that the ID assignment scheme in that writeup is specific to that agency, especially the part about the second digit of a radio ID always being zero. For example, while 755011 isn't in use on that system because of their ID assignment policy, it's perfectly valid on other systems.
Anyway, it was a really good writeup Larry. Thanks.
You are correct, As I said, this is a very old write-up, We have moved up a little, and now support "3600 digital", the ID's that are accoicated with the digital format are...
733100 , This used to be 701100 TRAF-P-316 (My Radio).
733001 - 733999 Are Digital capable Portables.
734001 - 734999 Are Digital capable Mobiles.
Have not had the need to add digital Base radios yet, but they will follow the same format.
As a note to the thread, If you support "Mixed-Mode" 3600, your ID's are basically split in half. This is done in the CSC so it will know which rescources are digital capable.
To see unit ID on an ASTRO radio, it must have the Display ID option. In addition, you are almost always guarenteed to see the ID on an ASTRO system, but you need more recent firmware to see ID's on an analog system.
Some people with recent firmware still cannot see ID's on an analog system, while others can. Haven't figured that one out yet. It seems that boards that came from non-800 radios seem to work, when placed in 800MHz radios.
Lowband radio. The original and non-complicated wide area interoperable communications system
