Data header and data block formats – Codan Radio P25 Training Guide User 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
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