User Manual

Airlink Pro T1/E1 Rack Mount Installer’s Guide
Operations and Maintenance
Rev. B - 1/97
4-11
❚ Receive Signal Quality (RSQ)
The AirLink Pro T1/E1 Rack Mount uses a Cyclic Redundancy Check (CRC)
error-checking system that constantly monitors the link error performance. The
CRC calculation is only performed on the T1/E1 payload. The CRC sequence is a
16-bit sequence that is appended to the end of the burst. The receiver on the
other end uses the same CRC-16 algorithm to perform the check on the received
burst and then compares the result. If the two checks do not match, the system
declares a CRC-16 error and increments the CRC-16 counter. Whether errored or
not, the CRC-16 sequence is removed and the payload is passed through to the
DSX-1 interface.
Viewing Performance Information
To view the performance information for the local unit, type the following
command at the AirLink Pro T1/E1 Rack Mount prompt:
AIRLINK PRO T1/E1> query performance
The system displays a list of performance information similar to the following:
AIRLINK PRO T1/E1> query performance
Site Name: Sunnyvale 2
QRSS BER: Unavailable
1 HR ES: 1
1 HR UAS: 0
24 HR ES: 1
24 HR UAS: 0
RSQ: 10
The following sections contain significance information about these categories.
QRSS BER
When the QRSS test is active, the Quasi-Random Signal Sequence Bit Error
Rate (QRSS BER) is the count of QRSS bit errors detected. The error counter
normally used to count CRC-16 errors is used instead to count QRSS bit errors.
When the QRSS test is active, the count of ES and UAS errors is suspended and
the existing values held, unaffected by the QRSS test. These counts are
reactivated when the QRSS test is terminated.
The results of the QRSS BER calculation are displayed in one of the following
forms:
unavailable When QRSS test is not selected, the word unavailable is
displayed.