A little bit on the MPT1327 System ID
I got asked about MPT1327 the other day and thought I should share the same information with the Motorola community.
One channel
in a MPT1327 trunked system is allocated to operate as a Control Channel. The Control
Channel continuously transmits information about calls and the system itself. Radios
which are not in a call will monitor the Control Channel – these radios will
also remain muted
Calls are
set up using the Control Channel and when a radio is called, it will move from
the Control Channel to one of the Traffic Channels allocated by the system.
The information
sent out on the Control Channel is known as the Control Channel System Codeword. This Codeword is made
up of 128 bits and is sent continuously on the control channel at 1200bps using
FFSK. 64 bits of this Codeword contain address information (which calls are
active) and the other 64 bits contain system information (known as the System
Codeword). Within the latter 64 bits, is the System Identity.
The System
Identity is contained within the System Codeword and occupies 15 bits. The System
Identity contains the following information:
System
Type: Regional or National.
- Operator Identity: 2 or 7 bits. The customer or telecommunications regulator will allocate this number and it depends on whether the system is a regional or national network.
- Network Dependent Data: There are three parameters included within NDD, these include Area Zone and SIL. These allow the customer to segregate the system into areas which users can or cannot operate in. The number of bits allocated to this is dependant on whether the system is regional or national.
- Label: Each site can have a label that can be used to prevent radios from registering on that site.
The below
diagrams shows two examples of a MPT1327 System ID. The first one is a regional
network hence bit 1 is set to zero. In both cases the Operator ID is 1 (decimal).
Also, in both cases the NDD is set to nothing so the system ID does not provide a means for restricting users from specific sites. The Label subfield is set to 001 which equates to Category
A in the CPS and system management software.
1
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2
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3
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4
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5
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6
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7
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8
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9
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10
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11
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12
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13
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14
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15
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Type
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Operator ID
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NDD
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Label
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0
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0
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0
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0
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0
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0
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0
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1
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0
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0
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0
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0
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0
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0
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1
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In the
above example, the system ID is represented as 0081 in Hexadecimal.
1
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2
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3
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4
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5
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6
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7
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8
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9
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10
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11
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12
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13
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14
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15
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Type
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Op. ID
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NDD
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Label
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1
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0
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1
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0
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0
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0
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0
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0
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0
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0
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0
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0
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0
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0
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1
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In the
above example, the system ID is represented as 5001 in Hexadecimal.
The System
ID, to which the radio is registered or has scanned, can also be seen by pressing 120#6 on a portable radio keypad.
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