User guide

5-10 Solo E1 DSU User Guide—June 1998
5
Pattern Tests
Table 5-2 contains a list of these pattern tests.
The QRW Test
QRW (Quasi Random Word) is a pseudo random signal which catches
problems not exposed by other test patterns. The DSU/CSU transmits a
QRW pattern to the E1 network, the remote system loops it back to the
DSU/CSU which monitors the signal for QRW bit errors.
You can also use the QRW code to isolate a E1 network problem to a
speciÞc transmission direction. In this case, both E1 transmission directions
are monitored when the local and the remote system transmit QRW (the
remote is not put into loopback).
This test is available on any fraction of the E1.
To simulate live trafÞc, QRW testing is strongly recommended.
The Send 1:7 Test
This pattern stresses the timing recovery circuits of repeaters and other
intermediate equipment.
The Send 3:24 Test
This pattern tests for 1s density (consecutive zeros) tolerance on AMI lines.
The Send 1:1 Test
This pattern sends alternate 1s and 0s to test for bridge taps.
The Send All Ones Test
This pattern is used for signal power measurements. All 1s simulates the
highest spectral components and the highest energy out of the DSU/CSU
and out of the line repeaters on the E1 line.
The Send All Zeros Test
This pattern checks the correct operation of the HDB3 (E1) line coding.