Black Box LRU4240 - Manual (Page 80)

68 SALES: 0870 90 10 750 Dual Trunk E1 Router User’s Guide
Dual Trunk E1 Router
Figure 8-2 Loop Up/Down Remote Test
Pattern Tests
QRW Pattern Test
Use the Quasi-Random Word (QRW) test to measure Bit Error Rates on the network. The Dual
Trunk E1 Router sends a QRW pattern into the network and monitors the received E1 network
signal for QRW bit errors. QRW is a good approximation of actual user data. It is also known in the
industry as Quasi Random Signal State (QRSS).
This test also looks for bit errors in both E1 circuit directions when the remote system is looped up.
In this case, the system transmits the QRW to the E1 network; the remote system loops it back to
the Dual Trunk E1 Router which monitors the signal for errors.
You can also use the QRW code to isolate a E1 network problem to a specific 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).
Other Pattern Tests
Other pattern tests types are listed and described in Table 8-2 .
NOTE: The full bandwidth loop up code puts the remote Dual Trunk E1
Router in a full bandwidth network loopback.
Table 8-2 Send Test Types Descriptions
Send Test Type Pattern Test Description
1:7 Pattern Stresses the timing recovery circuits of repeaters and other intermediate equipment.
1:1 Sends alternate ones and zeros—used to test for bridge taps.
All Ones Used for signal power measurements.
DSU
Network
Interface
Data
Port
Network
Interface
E1
E1
Data
Port
LOCAL
Dual Trunk E1 Router
REMOTE
Dual Trunk E1 Router
CSU DSU CSU
WAN
LOOP UP REMOTE
DSU
Network
Interface
Data
Port
Network
Interface
E1
E1
Data
Port
LOCAL
Dual Trunk E1 Router
REMOTE
Dual Trunk E1 Router
CSU DSU CSU
WAN
LOOP DOWN REMOTE