psf21911 ETC-unknow, psf21911 Datasheet - Page 46

• Manufacturer Part Number: psf21911
• Description: Isdn Echocancellation Circuit Terminal Applications Iec-q
• Manufacturer: ETC-unknow

PSB 21911
PSF 21911
U-Transceiver
2.5.1.2
Block Error Counters
The U-transceiver provides internal counters for far-end and near-end block errors. This
allows a comfortable surveillance of the transmission quality at the U-interface. In
addition, MON-1 messages indicate the occurrence of near-end errors, far-end errors,
and the simultaneous occurrence of both errors.
A block error is detected each time when the calculated checksum of the received data
does not correspond to the control checksum transmitted in the following superframe.
One block error thus indicates that one U-superframe has not been transmitted correctly.
No conclusion with respect to the number of bit errors is therefore possible.
The following two sections describe the operation of near and far-end block error
counters as well as the commands available to test them.
Near-End and Far-End Block Error Counter
A near-end block error (NEBE) indicates that the error has been detected in the receive
direction (i.e. NEBE in the NT after an LT --> NT error). This will be indicated with a MON-
1-message NEBE. Each detected NEBE-error increments the 8-bit NEBE-counter.
When reaching the maximum count, counting is stopped and the counter value reads
(FF
).
H
The current value of the NEBE counter is read with the MON-8 command RBEN. The
response comprises two bytes: the first byte always indicates that a MON-8 message is
replied to (80
), the second represents the counter value (00
) … (FF
). Each read
H
H
H
operation resets the counter to (00
).
H
A far-end block error identifies errors in transmission direction (i.e. FEBE in the NT = NT
=> LT-error). FEBE errors are processed in the same manner as NEBE errors. A far-end
block error will be indicated with a MON-1 message FEBE. The FEBE counter is read
and reset with the MON-8 command RBEF.
In case both, far-end and near-end block errors occur simultaneously, the MON-1
message FNBE will be issued.
Both counters are also reset in all U-transceiver states except ’Synchronized’, ’Wait for
Act’, ’Transparent’ and ’Error S/T’.
Semiconductor Group
46
11.97