PEB22554 SIEMENS [Siemens Semiconductor Group], PEB22554 Datasheet - Page 254

• Manufacturer Part Number: PEB22554
• Description: ICs for Communications
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

PEB 22554
Functional Description T1 / J1
Remote Alarm (yellow alarm) Generation / Detection
Remote alarm (yellow alarm) is indicated by the periodical pattern ‘1111 1111 0000
0000 …’ in the DL bits. Remote alarm will be declared even in the presence of BER
1/1000. The alarm will be reset when the ‘yellow alarm pattern’ no longer is detected .
Depending on bit RC1.SJR the QuadFALC will generate and detect the Remote Alarm
according to JT G. 704. In the DL-bit position 16 continous „1“ are transmitted if
FMR0.SRAF=0 and FMR4.XRA=1.
CRC6 Generation and Checking
Generation and checking of CRC6 bits transmitted/received in the e1-e6 bit positions is
done according to ITU-T G.706. The CRC6 checking algorithm is enabled via bit
FMR1.CRC. If not enabled, all check bits in the transmit direction are set to ‘1’. In the
synchronous state received CRC6 errors are accumulated in a 16 bit error counter and
are additionally indicated by an interrupt status.
– CRC6 Inversion
If enabled by bit RC0.CRCI, all CRC bits of one outgoing extended multiframe are
automatically inverted in case a CRC error is flagged for the previous received
multiframe. Setting the bit RC0.XCRCI will invert the CRC bits before transmitted to the
distant end. This function is logically ored with RC0.CRCI.
– CRC6 Generation / Checking According to JT G. 706
Setting of RC1.SJR the QuadFALC will generate and check the CRC6 bits according to
JT G. 706. The CRC6 checksum is calculated including the FS/DL bits. In synchronous
state CRC6 errors will increment an error counter.
7.7.4
72-Frame Multiframe (SLC96 )
The 72-multiframe is an alternate use of the FS-bit pattern and is used for carrying data
link information. This is done by stealing some of redundant multiframing bits after the
transmission of the 12-bit framing header (refer to table 25). The position of A and B
signaling channels (robbed bit signaling) is defined by zero-to-one and one-to-zero
transitions of the FS bits and is continued when the FS bits are replaced by the data link
bits.
Remote Alarm (Yellow Alarm) is indicated by setting bit 2 to zero in each time-slot. An
additional use of the D bits for alarm indication is user defined and must be done
externally.
Semiconductor Group
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