Installation guide

LTU/NTU SZ-DOC-W5-1.pd
f
Operating Manual
V
ersion: 1.5
Revision: 2002-09-10 12
3.2.1.2.2 E-bit Insertion
• If automatic E-Bit generation is enabled, detected CRC4 errors will cause the assertion of
the E-bits.
• If disabled, all E-Bits are set to ‘1’.
3.2.2 AIS Generation
If this option is enabled, an unframed AIS (all ones) will be transmitted on the E1 side,
irrespective of whether the system is configured in transparent or framed mode.
AIS generation will be activated on the following conditions:
• DSL link to the remote station is not established (loss of signal or loss of frame alignment on
DSL side) or
• remote station is sending AIS-R.
If AIS generation is disabled, no signal will be transmitted on the E1 side if either of these two
conditions occurs.
3.2.3 AIS Detection
If AIS detection is enabled, receiving AIS from the E1 side will cause the following actions:
• The Non-Urgent alarm will be set active (AIS-S).
• AIS will be transmitted to the remote station by AIS-R.
3.2.4 E1 Clock Modes
3.2.4.1 Clock Sources
The following block diagram shows the possible clock sources for the LTU and the NTU (Note,
that the external clock option is not available for the NTU!). The clock sources are intended to be
references only and do not drive the DSL transmit section physically.
Data rate adaptation between the 2048kHz clock and the DSL transmit clock is achieved by
stuffing / deleting bits in the DSL frames.
The crystal controlled DSL clock never affects the E1 interface clock.