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CMX7143 Multi-Mode Wireless Data Modem
Function Image™ FI-2.0 - 4FSK Modem Overview
•
•
Configurable data rates up to 19.2kbps
Packet data definition as defined within the FX/MX919B datasheet
o
Symbol Sync
o
Flexible frame structure, header, intermediate and last blocks can all be:
6bytes, 9bytes or 12bytes
o
Frame Sync
Default FX/MX919B
User programmable
o
Header block
CRC coding/decoding
o
Intermediate blocks
o
Last blocks
CRC coding/decoding
o
FEC Trellis coding/decoding
o
Interleaving/de-interleaving
Frame construction/destruction utilising a data buffer
Header Block
7 6 5 4 3 2 1 0
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Byte 8
Byte 9
Byte 10
Byte 11
CRC2
(4 bytes)
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Intermediate Blocks
7 6 5 4 3 2 1 0
Last Block
7 6 5 4 3 2 1 0
Data Bytes
(10)
Data Bytes
(12)
Data Bytes
(8)
CRC1
(2 bytes)
7
Byte 0
07
Byte 1
0
7
Byte 11
0
'000'
tri-bits
0
1
2
3
4
5
29
30
31
32
FEC TRELLIS CODING / DECODING
( ERROR CORRECTION )
4-level
symbols
0
1
2
64
65
INTERLEAVING / DE-INTERLEAVING
Over-air
signal
(symbols)
SYMBOL
SYNC
FRAME
SYNC
24
'HEADER'
BLOCK
66
66
INTERMEDIATE BLOCKS
66
'LAST'
BLOCK
66
FRAME
PREAMBLE
FRAME
Frame Sync:
-1
+1
-1 +1
-1
+3
-3 +3
-3
-1 +1
-3 +3
+3
-1
+1
-3
-3 +1
+3
-1
-3 +1
+3
sent first
Symbol Sync : at least 24 symbols of '..+3 +3 -3 -3 ...' sequence
© 2007 CML Microcircuits
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