CMX969P4 查看數據表（PDF） - MX-COM Inc

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CMX969P4

MOTIENT/ARDIS RD-LAP MDC4800 Modem

MX-COM Inc  

MOTIENTSM/ARDISSM RD-LAPTM MDC4800 Modem

11

CMX969 Advance Information

4.4.2 RD-LAP Mode

The CMX969 Frame Structure in RD-LAP mode is illustrated in Figure 6, and consists of a Frame Preamble

(comprising a 24-symbol Frame Synchronization pattern and Station ID block) followed by one or more

'Header’ blocks, one or more 'Intermediate’ blocks and a 'Last’ block. Channel Status (S) symbols are

included at regular intervals. The first Frame of any transmission is preceded by a Symbol Synchronization

pattern.

Byte 0

Byte 1

Byte 2

Byte 3

Station ID

msb

lsb

765 43 21 0

System ID

Domain ID

Base ID

CRC0

Header Block

Byte 0

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

Byte 7

Byte 8

Byte 9

Byte 10

Byte 11

765 43 21 0

Address

&

Control

(10 bytes)

CRC1

(2 bytes)

Intermediate Blocks

7 65 43 21 0

Last Block

7 654 321 0

Data Bytes

(12)

Data bytes

(0 - 8)

Pad bytes

(0 - 8)

CRC2

(4 bytes)

7

07

07

07 2 0

Byte 0

Byte 1

Byte 2

Byte 3

'000'

0 12

8 9 10

tri-bits

7

07

0

Byte 0

Byte 1

0 12 34 5

7

0

Byte 11

'000'

29 30 31 32

FEC TRELLIS CODING / DECODING

( ERROR CORRECTION )

01

20 21

4-level

symbols

FEC TRELLIS CODING / DECODING

( ERROR CORRECTION )

0 12

64 65

INTERLEAVING / DE-INTERLEAVING

Block:

22 symbols

S

22 symbols

S

22 symbols

S

Over-air

signal

(symbols)

SYMBOL

SYNC

FRAME

SYNC

S

STATION

ID

S

'HEADER'

BLOCK

24

24 1 22

1

69

FRAME

PREAMBLE

INTERMEDIATE BLOCKS

69

69

PACKET (1 TO 44 BLOCKS)

FRAME

'LAST'

BLOCK

69

FRAME

SYNC

NEXT FRAME

(OPTIONAL)

'S' : Channel Status Symbol : +3 = Busy +1 = Unknown -1 = Unknown -3 = Idle

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

Symbol Sync:

+3 +3 -3 -3 +3 +3 -3 -3 +3 +3 -3 -3 +3 +3 -3 -3 +3 +3 -3 -3 -3 -3 +3 +3

sent first

last

Figure 6: RD-LAP Over Air Signal Format

¤2001 MX-COM, Inc.

www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054

Doc. # 20480211.002

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

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