Avaya Definity SI Maintenance Manual page 886

Maintenance Object Repair Procedures
Loop Around and Conference Test (#47)
Each Analog Port consists of:
an NPE for port connectivity and gain, and conferencing functionality
a code that converts the digital signals of the TDM Bus to analog signals
a battery feed chip that provides power to the telephone set for signaling,
dial pulsing, transmission, and balance.
This test is designed to check the on-board transmission capabilities of the NPE,
the code, and the battery feed chip of the Analog Port. A Tone Detector and a
Tone Generator talk and listen on the same pair of time slots as the Analog Port.
The Analog Port is then instructed to go into loop around mode (see Figure 10-2).
The test passes if the signal measured by the Tone Detector is within acceptable
limits.
The Conference Circuit Test verifies that the NPE channel for the port being
tested can correctly perform the conferencing function. As part of Test #47, the
operation of the port conference circuits in the NPE for three and four parties is
also tested. In addition, a test is run to measure noise. The NPE is instructed to
listen to several different tones and conference the tones together. The resulting
signal is then measured by a Tone Detector port. If the level of the tone is within a
certain range, the test passes.
The noise test is performed by filtering out the tone, and then measuring inherent
port noise.
NOTE:
This Loop Around Test is sensitive to the length of the loop, the equipment in
the loop, or the equipment terminating the loop, such as off-premises
stations. If this test is causing a false alarm, then disable the test by
changing the Tests field to n using the change station command for this
station.
10-100 Issue 4 May 2002 555-233-123