MT312C ZARLINK [Zarlink Semiconductor Inc], MT312C Datasheet - Page 36

• Manufacturer Part Number: MT312C
• Description: Satellite Channel Decoder
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

MT312
6 QPSK demodulator
6.1 QPSK Demodulator Read/Write Registers
6.1.1 Symbol Rate. Registers 23 - 24 (R/W)
B15:
B14:
B14:
If SYM RATE[15:14] = 0 this is the non-search mode, i.e. the known Symbol rate mode.
If any of the two DSS bits are set in the CONFIG register, then the SYM RATE register contents are ignored
and the symbol rate is taken as 20 MBaud. Hence it is not necessary to program the SYM RATE register for
DSS applications.
The total symbol rate range is divided into 12 sub-ranges. A bit in the above register pair is assigned to each
sub-range, as defined in the tables below. The symbol rate sub-range or sub-ranges to be searched are defined
by setting the appropriate bits high. Small overlaps are automatically provided between successive sub-ranges.
Note that the lowest sub-ranges have been provided for 90 MHz operation and the device has not been
optimised for operation below 1 MBaud.
36
SYM RATE H
SYM RATE L
NAME
SEARCH
Reserved.
S FMT
B13-0:
If SYM RATE[15:14] = 1x this is the Search Mode where x = don't care.
B11-0:
QPSK Demodulator
ADR
23
24
Must be set low
Sweep MT312 Format.
Required Symbol rate in Mbaud x 256. Unsigned 14 bit number. e.g. for a symbol
rate of 27.5 MBd
SYM RATE = 27.5 * 256 = 7040 = 1B80 (hex)
Sub-ranges to be searched (scaled by clock rate).
SEARCH
B7
Reserved
B6
SYM RAT[7:0] in Mbaud (low byte)
B5
SYM RATE[13:8] in MBaud (high byte)
B4
B3
B2
B1
B0
R/W
R/W
Def
hex
80
80