MT312 Zarlink Semiconductor, MT312 Datasheet - Page 46

• Manufacturer Part Number: MT312
• Description: Satellite Channel Decoder
• Manufacturer: Zarlink Semiconductor

The majority of these interrupts are for diagnostic purposes and generally not useful in normal operation, unless
otherwise indicated.
bit-7:
bit-6:
bit-5:
bit-4:
bit-3:
bit-2:
bit-1:
bit-0:
Reading an Interrupt register resets that register.
Frequency and symbol rate search is carried out as follows. If the symbol rate is known then MT312 will search the
specified frequency range for this symbol rate. Once the end of this range has been reached, "QPSK end of
frequency range search" interrupt will be issued and MT312 will resume the search beginning from frequency zero.
A "QPSK end of symbol rate range(s) search" interrupt will not be issued.
If the symbol rate is not known, then MT312 can be made to search several sub-ranges of symbol rates, by setting
up to 12-bits of the pair of SYM_RATE registers, as described in “Symbol rate registers 23 - 24 (R/W)” on page 39.
For illustration purposes, assume that the symbol rate sub-ranges SYS_CLK/2 to SYS_CLK/3 and SYS_CLK/4 to
SYS_CLK/6 are to be searched. Then MT312 will begin the search from the upper sub-range SYS_CLK/2 to
SYS_CLK/3. MT312 will search for a channel with a symbol rate in this range over the specified frequency range,
for example ± 10 MHz. If no channel is found then MT312 will issue a "QPSK end of frequency range search"
interrupt and will go on to search the sub-range SYS_CLK/4 to SYS_CLK/6 over the specified frequency range. If
no channel is found, then MT312 will issue a "QPSK end of frequency range search" interrupt as well as a "QPSK
end of symbol rate range(s) search" interrupt. Then MT312 will return to search the specified frequency range for a
symbol rate in the range SYS_CLK/2 to SYS_CLK/3. This process continues indefinitely, unless it is interrupted by
host processor software.
QPSK_INT_L
NAME
High = QPSK state change
High = QPSK frequency end of search range - important indicator.
High = QPSK_BAUD end of range - important indicator.
High = QPSK_AFC success
High = QPSK_AFC fail
High = QPSK next frequency search
High = QPSK same frequency search
High = QPSK LTV limit
ADR
02
bit-7
bit-6
QPSK_INT[7:0] Interrupt QPSK (low byte)
bit-5
Zarlink Semiconductor Inc.
bit-4
MT312
46
bit-3
bit-2
bit-1
bit-0
R
hex
Def
00
Design Manual