MAS9191AJ MAS [Micro Analog systems], MAS9191AJ Datasheet - Page 12

• Manufacturer Part Number: MAS9191AJ
• Description: Single Chip AMPS/ETACS/NAMPS Audio/Data Processor
• Manufacturer: MAS [Micro Analog systems]

FUNCTIONS
◆
The data reception block is in the power down state
after a reset. The power down mode of the block is
controlled by the RXSIP bit in register 07
Manchester encoded data is received through the RX
pin. The data is amplified with GC1 and filtered with
filter F1. The comparator C1 is used to convert data to
a digital signal. The digital PLL circuit recovers the bit
clock from the Manchester encoded data. The bit
clock is 8kHz in the ETACS mode and 10kHz in the
AMPS mode. The mode is set with the SYS0 bit of
register 12
Manchester decoder and the data is then transmitted
to the frame decoding block. The frame decoding
Forward control channel data format. The numbers under the frames show the number of bits in each section.
bit sync
The busy/idle bits are extracted from the data.
Busy/idle bits are used to indicate the current status
of the reverse control channel (RECC). The RECC is
busy if the busy/idle bit is low and idle if the busy/idle
Forward voice channel data format.
On the forward voice channel after bit synchronization
and word synchronization are received and the AUMUT
bit in register 13
will be muted until the 920 bits are received. The
repeated words are transferred to the voting block. The
voting is done bit by bit, 3-out-of-5. If three consecutive
words are identical, the receiver is powered down and
no remaining words are read. After the voting block the
data is transmitted to the BCH block. This block
performs decoding of the received BCH coded data.
The following polynomial is used:
Busy/
Bit Sync
Idle
1
Data Reception
101
G(x) = x
= 1010101010
Busy/
Busy/
Data
Idle
Idle
HEX
10
1
1
Bit Sync
Word
Sync
. The recovered bit clock is used in the
11
37
HEX
12
Busy/
Sync
Data
Idle
+ x
Bit
10
10
1
is set to high, the RX audio block
10
word sync = 11100010010
1.Word
1. Repeat of word B
repeat
+ x
Word
Sync
40
11
Busy/
Busy/
Data
8
Idle
Idle
10
+ x
1
1
5
5. Repeat of word B
+ x
Bit Sync
9.Word
Busy/
repeat
Word
Sync
Data
4
Idle
11
10
+ x
37
40
1
3
+ x
Busy/
Busy/
HEX.
Data
0
Idle
Idle
10
Bit Sync
1
1
Word
Sync
11
37
The
Busy/
Data
Data
Idle
10
10
1
2.Word
repeat
Word
Sync
bit is high. The state determination is made with
2-out-of-3 voting. The TX block uses the busy/idle
indication for arbitration. The STR bit of register
12
40
11
block finds dotting sequences, busy/idle bits and word
syncs from the data. To avoid data being generated
by random noise, the frame decoding block enters the
data reception mode only after it has received two
consecutive word syncs (11100010010) separated by
463 bits in the forward control channel and 77 bits in
the forward voice channel. In this case the voting and
BCH block are activated. When the frame decoding
block loses five consecutive synchronization patterns
it rejects the data reception mode and sets the voting
and BCH blocks in power down state. The voice and
control channel modes are selected with the CTCV bit
of register 12
If only one error occurs in data the BCH block can
correct it. If more than one error occurs the BCH block
cannot correct them and the BCHER bit of register
11
to the RX buffer. When the buffer is full the RXWRD bit
of register 10
line XINT to go active. When register 10
interrupt is cleared. The data buffer can be read by
reading register 15
coming and the previous word has not been read from
the buffer, the word is missed. The new and the old
words are compared.
Busy/
Busy/
Data
HEX
Idle
Idle
10
HEX
1
1
selects the words from stream A or stream B.
is set to high. The BCH block transfers the data
1. Repeat of word A
10.Word
Bit Sync
repeat
Busy/
Data
Data
Idle
37
40
10
10
1
HEX
HEX
.
is set to high and this causes interrupt
Busy/
Busy/
Data
HEX
Bit Sync
Idle
Idle
10
2. Repeat of word A
1
1
Word
Sync
11
37
four times. If the next word is
Busy/
Sync
Data
Idle
Bit
10
10
1
3.Word
repeat
Word
Sync
40
11
DA9191A.000
July 31, 1997
Busy/
Busy/
Data
Idle
Idle
10
1
1
HEX
11.Word
repeat
is read the
40
Data
10
12