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Digital Test
The Digital Test uses the digital circuitry of the data origin node VLBRV Channel to generate a
digital "quiet channel pattern." If the data origin node is the same as the loopback point (a local
loopback) the digital pattern is looped back at the interface between the Transmit/Receive Logic
Plus module and the VLBRV Channel Module. If the loopback point specified is at the opposite
node from the data origin (a remote loopback) the digital pattern is looped back within the digital
circuitry of the remote VLBRV Channel Module. The data origin VLBRV Channel Module eval-
uates the returned digital signal, and develops an error count which is displayed in the channel
status scan. This test is used after a VF Idle Test, to determine if a noise problem is originating in
the digital or VF section of the VLBRV Channel Module. Figure 4 illustrates the loopback paths
of a Digital Test.
User Data Test
The User Data test requires that external test equipment be connected to the data origin node VL-
BRV Channel to generate test signals and evaluate them. Loopbacks may be selected at the data
origin node channel digital interface, or the opposite-end channel digital interface. Figure 5 shows
the loopback paths of a User Data Test with a Node M data origin.
The following instructions apply to VLBRV channel data path tests (separate instructions are giv-
en below for Rcv dB levels):
1.
If you are using external test equipment, connect the test equipment to the originating chan-
nel interface.
2.
Select Channel diagnostics from the Diagnostics Functions Menu. Specify the channel by
name or number. Selecting channel diag-nostics suppresses all Out-Of-Sync alarms on the
VLBRV Channel Module.
3.
Using the cursor position and Return key, select the Data Path Tests.
4.
When the Data Path Test display appears, use the up and down cursor position keys to po-
sition the cursor at the desired test.
5.
Use the left and right cursor position keys to move the cursor to the DATA ORIGIN or
LOOPBACK POINT fields. Use the up and down cursor position keys to alternate between
Node M and Node S for data origin or loopback point.
6.
When the desired data origin and loopback point have been selected, press Return to initiate
the test. If you are using external test equipment to generate test signals, begin the signal
generation. The channel Diagnostics Menu returns to the screen, and the channel status
scan reports the test. If the selected test has displayed test results, the results are displayed
in the status scan.
7.
To terminate the test, select Data Path Tests from the Diagnostic Menu. When the Data Path
Test display appears, select STOP TEST and press Return. The status scan will indicate the
test has completed.
7
036R660-E1
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