AD9853 Analog Devices, AD9853 Datasheet - Page 12

• Manufacturer Part Number: AD9853
• Description: Programmable Digital OPSK/16-QAM Modulator
• Manufacturer: Analog Devices

AD9853
WORD STRUCTURE
INTERNAL CODE-
AT R-S OUTPUT
A
T
OUT
X
NOTES ON BURST TRANSMISSION OPERATION:
1. PACKET LENGTH = NUMBER OF INFORMATION BYTES, K
2. IN FEC MODE T
3. IF NECESSARY, ZERO FILL THE LAST CODEWORD TO REACH ASSIGNED K DATA BYTES PER CODEWORD
4. THE INPUT DATA IS SAMPLED AT THE BIT RATE FREQUENCY (f
5. PREAMBLE DELAY =
6. DATA RATE MUST BE EXACT SUB-MULTIPLE OF REFERENCE CLOCK.
ENABLE TO
T
T
T
BIT CLOCK
ENCODER
INTERNAL
X
X
X
RISING EDGE OF T
LATENCY
ENABLE
DATA IN
ENABLE
DATA IN
ENABLE
DATA IN
INPUT
COMPLETE FRAME AS PRESENTED TO MODULATOR ENCODER:
X
ENABLE MUST BE KEPT HIGH FOR N
FRAME STRUCTURE FOR MULTIPLE CODE WORDS OR CONTINOUS TRANSMISSION:
INPUT DATA PROCESSING:
D1 D2 D3 D4 D5 D6 D7 DN
D1 D2 D3 D4 D5 D6 D7 DN
X
FRAME STRUCTURE: MIN T
ENABLE
NOTE: DATA RATE MUST BE PRECISELY
D1
(BIT RATE FREQUENCY)
(# OF PREAMBLE BITS)
DATA PACKET = K BYTES
DATA PACKET = K BYTES
PREAMBLE
SYNCHRONIZED WITH RISING EDGE
OF T
PREAMBLE LENGTH = 96 BITS MAXIMUM
DURING THIS INTERVAL THE DATA IS R-S ENCODED, RANDOMIZED, AND
DELAYED TO SYNCHRONIZE WITH THE END OF THE PREAMBLE DATA.
D2
X
ENABLE
Figure 26. Data Framing and Processing
ONE CODEWORD
D3
MINIMUM SPACING BETWEEN BURSTS WITH NO CHANGE IN PROFILE)
X
ENABLE LOW TIME = PREAMBLE + 8 SYMBOLS. (EQUATES TO 8 SYMBOLS
D4
(K+2T) BYTES WHERE N IS THE NUMBER OF CODEWORDS
DON'T CARE
DON'T CARE
FEC PARITY
FEC PARITY
D5
(2T BYTES)
(2T BYTES)
PREAMBLE INSERTION
B
–12–
) WITH THE FIRST SAMPLE TAKEN AT
D1 D2
D59
D1 D2 D3 D4 D5 D6 D7 DN
DATA PACKET = K BYTES
DATA PACKET = K BYTES
D3 D4 D5 D6 D7 DN
D60
CODEWORD(S)
D61
ONE CODEWORD
2
D62
1
(f
B
)
DON'T CARE
D63
FEC PARITY
SECONDS AFTER THE
(2T BYTES)
DON'T CARE
FEC PARITY
(2T BYTES)
D64
DATA
PACKET
AND
FEC PARITY
D65
D1
DN
D2
REV. C