5.3.2. Remote Digital Loopback (RDL)
The Remote Digital Loopback test checks the performance of both the local and remote Model 1186s, and the communication link between them. In this test, any characters sent from the originating device to the remote unit will be returned (see Figure 12). Any data sent from the remote DTE wil be ignored.
G.703/G.704
Network
Figure 12. Remote Loopback Diagram
To perform a RDL test, follow these steps:
1.Activate RDL by moving front panel toggle switch DOWN to "Remote". The TM LED on both local and remote units will light up.
2.Perform a BER (Bit Error Rate) test on the system, using BER tester on the local end. BER test can also be performed using
3.If the BER test equipment indicates a fault and the Local Analog Loopback test was successful for both Model 1186s, there may be a problem with the line between the units.
4.Upon completion of the RDL test, return the front panel switch to the NORMAL position. The TM LED should turn off on both local and remote units.
5.3.3. V.52 Test Pattern Generator
To use the V.52 BER test in conjunction with the Local or Remote Loopbacks, follow these instructions:
1.Locate the "511/511E" toggle switch on the front panel of the Model 1186 and move it UP. This activates the V.52 BER test mode and transmits a "511" test pattern into the loop. If any errors are present, the local modem's red "ER" LED will blink intermittently.
2.If the above test indicates no errors, move the V.52 toggle switch DOWN, activating the "511/E" test with errors present. If the test is working properly, the local modem's red "ER" LED will blink once every two seconds. A successful "511/E" test will confirm that the link is in place, and that the
Note: When the unit is set for Network Clock Mode, the unit will derivew its timing from the G.703/G.704 Interface. Failure to connect to G.703/G.704 may result in bit errors during the 511 or 511/E test.
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