Specifications

Watson TDM

Operating Manual

Watson-TDM-Manual-W.doc

Version 2.0-01

3-12

Revision: 2008-02-07

Digital Link with CRC Processing in the NT1 (Option 2)

This is the usual PRA operating mode as described in ETS 300 233 and ITU-T

Rec. G.962 Annex B. The PRA interface is intended to be used in this mode.

Local CRC error information

Remote CRC error information

CRC Monitor

CRC Generator

Optional

Mandatory

Digital Link

NT2

T V3'

NT1

Figure 3-11: Digital Link with CRC Processing in the NT1

CRC4 is generated towards the NT2/TE and towards the ET and monitored at

both sides of the NT1. When a block with a CRC4 error is received from the

NT2/TE, CRC4 error information is transmitted towards the NT2/TE (via E-bits)

and optionally towards the ET (via Sa6-bits). When a block with a CRC4 error is

received from the ET, error information is transmitted towards the ET (via E-bits).

CRC4 errors detected at the T reference point of the NT2/TE are reported to the

NT1 (via E-bits) and optionally towards the ET (via Sa6-bits). CRC4 errors de-

tected at the V3 reference point of the ET are reported to the NT1 (via E-bits).

Loopback 1 and 2 control facilities and monitoring of defect conditions are im-

plemented according to ETS 300 233.

Depending on the distribution of NT1 and LT functionality, two set-ups are possi-

ble for option 2:

• The master is E1 configured transparent, AIS-generation on and AIS-

detection off; the slave is PRA NT1 & LT, CRC4 processing on.

• The master is PRA LT with CRC4 monitoring on; the slave is PRA NT1 with

CRC4 processing on.