PEF24901HV22XP Lantiq, PEF24901HV22XP Datasheet - Page 77

• Manufacturer Part Number: PEF24901HV22XP
• Manufacturer: Lantiq

Specifications of PEF24901HV22XP

• Control Interface: HDLC
• Lead Free Status / Rohs Status: Compliant

from the hybrid is ignored in this mode. The analog loop mode is controlled via the IOM
2 C/I-channel code ’AR1’.
To request a LT-repeater to close the analog loop no.4, C/I code ’AR4’ must be applied
to the DFE-T V2.2. It will send in turn alternating plus and zero polarity within 8
subsequent frames in the M-channel (+ 0 + 0 + 0 + 0 ...).
4.4.1.2
Loopback no. 2 is controlled by the exchange. It is transparent which means that all bits
that are looped back are also passed on to the S-bus. The DFE-T V2.2 features the
remote control of loop no.2 via its C/I channel. C/I code ’AR2’ requests the NT to close
the loop, ’AR’ or ’DR’ requests the NT to open the loop again.
The DFE-T V2.2 translates the received C/I codes into the following pattern sequence in
the M-channel of the U-interface:
• continuous ’+’ polarity
• continuous ’0’ polarity
During normal transmission without loops, the M-symbol is set to zero.
The loopback comprises both B-channels and the D-channel. It is closed in the NT as
close to the S-transceiver as possible.
4.4.1.3
Besides the standardized remote loopbacks the DFE-T V2.2 features additional local
loopbacks for enhanced test and debugging facilities. The loopbacks that are additionally
available with the internal LOOP register are shown in
DFE-T V2.2 itself.
By the LOOP register it can be configured whether the digital looback is closed only for
the B1 and/or B2 or for all ISDN-BA channels and whether the loopback is closed
towards the IOM
The bit TRANS in the LOOP register allows for selection of transparent or non-
transparent loopback mode. In transparent mode the data is both passed on and looped
back. In non-transparent mode the data is not forwarded but substituted by 1 s (idle
code).
Note: The digital framer/deframer loopback (DLB) is always transparent.
Besides the loopbacks in the system interface a further digital loopback, the Framer/
Deframer loopback is featured. It allows to test all digital functions of the 4B3T U-
transceiver besides the signal processing blocks. However, an activation procedure is
Data Sheet
The NT closes loopback no.2 after 8 consecutive pulses with plus polarity has been
received in the M-channel (+ + + + + + + + ...).
The NT clears loopback no.2 after 8 consecutive zeros has been received in the M-
channel (0 0 0 0 0 0 0 0 ...) or on a deactivation request.
Loopback No.2
Available Loopbacks by Register Map
®
-2 interface or towards the U-Interface.
78
Figure
Operational Description
27.They are closed in the
PEF 24901
2002-09-30
DFE-T
®
-