Specifications

LOCAL FIBER MUX-6

4.4 System Tests

Two system tests are available in the Local Fiber Mux-6: local loopback and

remote loopback.

Local Loopback

When performing local loopback, the data from the local transmitter is

looped back to the local receiver at the digital level, thus checking all local

digital circuitry for proper operation. This test is activated by pressing the

LLB push-button located on the front panel. If the local unit is operating

properly, the yellow TEST indicator should light, and all other indicators

should be OFF. If the local and remote units are properly connected via the

main channel, the local transmitter analog interface and both the remote

analog and digital receiver sections are checked. The yellow TEST indicator

on the remote unit should also be lit if the units are properly connected.

Remote Loopback

Remote loopback loops back data from the remote receiver to the remote

transmitter, thus checking:

• All local digital circuitry

• Both local and remote analog interfaces

• Main channel link

• Remote digital receiver section.

This test is performed by pressing the RLB push-button on the front panel.

If both local and remote units operate properly, the yellow TEST indicators

should be lit at both units, and all other indicators should be OFF.

NOTE

When either local or remote loopback test is performed, the following

signals at the remote unit sub-channels are set to OFF (negative voltage)

condition:

• Received Data (Circuit 104)

• Clear to Send (Circuit 106)

• Receive Line Signal Detector (Circuit 109)