txc-03456 TranSwitch Corporation, txc-03456 Datasheet - Page 44

• Manufacturer Part Number: txc-03456
• Description: Device Level Mapper
• Manufacturer: TranSwitch Corporation

The ITU-T defined 16-byte message consists of an alignment signal of (10000000 00000000) in the most sig-
nificant bit (bit 1) of the message. The remaining 7 bits in each frame consists of a data message, as illustrated
below.
The J1 16-byte message comparison works according to the following steps:
1. Assume that the L4M J1 detector is out of lock, and there is no mismatch alarm.
2. A 16-byte reference message is written into the memory map by the microprocessor.
3. The incoming message is received, and the J1 comparison circuit searches for the multiframe pattern
4. Multiframe is found.
5. The incoming (received) 16-byte message is then checked for three consecutive 16-byte message repeats.
6. If an error occurs before step 5 is completed, the sequence repeats, starting at step 3.
7. If the incoming 16-byte message repeats three times in row (after the multiframe is detected) without an
8. This stable message is compared against the microprocessor-written message, byte for byte for 16-bytes
9. If the microprocessor-writes a new byte, a J1 Trace Identifier Mismatch (J1TIM) alarm will also occur
10. If the receive message changes for three consecutive 16-byte messages, an out of lock alarm occurs.
11. The sequence repeats.
When the J1 is not in lock (J1 lock equal to 0), a J1 loss of lock alignment alarm (J1LOL) is declared. This pro-
cess is inhibited and reset during an incoming AIS condition.
(1000...0 pattern).
error, the internal memory map segment is updated. This is an in-lock condition, and the J1 Loss of Lock
alarm is reset.
(the length of the multiframe message). If they compare, a match is declared. No mismatch alarm. If they
do not compare a mismatch alarm is declared. A J1 mismatch alarm results in RDI and AIS being sent
continuously, when enabled. There is no out-of-lock alarm because the received message is stable.
because the receive message is stable but there is mismatch between the two locations. A mismatch
alarm is declared, and RDI and AIS are sent continuously, when enabled. There is no out-of-lock alarm
because the received message is stable.
However, the mismatch alarm resets.
Bit
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ITU-T 16-Byte J1 Message Format
2
3
DATA SHEET
- 44 -
16-Byte J1 Message
4
5
6
7
8
Ed. 1A, January 2000
TXC-03456
TXC-03456-MB
L4M