Codan Radio P25 Training Guide - Manual (Page 67)

P25 RADIO SYSTEMS | TRAINING GUIDE
Chapter 4: Anatomy of the Common Air Interface Page 59
DATA HEADER AND DATA BLOCK FORMATS
Figure 4-13 shows the Header and Data Blocks for unconfi rmed and confi rmed data.
Figure 4-13: Unconfi rmed and Confi rmed Header and Data Blocks
A/N
%0 Unconfi rmed Data Packet
%1 Confi rmed Data Packet
I/O
%0 Inbound Message
%1 Outbound Message
0 A/N
Bit 7 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 Bit 1
Octet 0
Octet 6
Octet 5
Octet 4
Octet 3
Octet 2
Octet 1
Octet 9
Octet 8
Octet 7
Octet 11
Octet 10
Blocks to follow
MFID
Logical Link ID
SAP Identifier
1 0 I/O 1 1 0
1 1
1
0 0 Pad Octet Count
Reserved
Header CRC
Data Header Offset
0
0 0
Unconfirmed Data Header
Bit 7 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 Bit 1
Octet 0
Octet 6
Octet 5
Octet 4
Octet 3
Octet 2
Octet 1
Octet 9
Octet 8
Octet 7
Octet 11
Octet 10
User Data
User Data
or Packet CRC (Last Data Block Only)
Unconfirmed Data Block
0 A/N
Bit 7 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 Bit 1
Octet 0
Octet 6
Octet 5
Octet 4
Octet 3
Octet 2
Octet 1
Octet 9
Octet 8
Octet 7
Octet 11
Octet 10
Blocks to follow
Confirmed Data Header
MFID
Logical Link ID
SAP Identifier
1 0 I/O 1 0 1
1 1
FMF
Header CRC
0 0 Pad Octet Count 0
Data Header Offset 0 0
N(S) Syn FSNF
Bit 7 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 0 Bit 1
Octet 0
Octet 6
Octet 5
Octet 4
Octet 3
Octet 2
Octet 1
Octet 9
Octet 8
Octet 7
Octet 11
Octet 10
User Data
CRC-9
Data Block Serial Number
User Data
or Packet CRC (Last Data Block Only)
Confirmed Data Block
Rate 1/2 Trellis Encoder Rate 3/4 Trellis Encoder