Nortel DMS-100 Series Maintenance Manual page 231

Star Remote System manual maintenance 7-27
Both of them are connected to the Star Hub.
The CALRS test desk or 4TEL device connects to the metallic test access
(MTA) in the host office. The MTA connects through the MDF to tip, ring, and
sleeve connections on the external tester (digital remote test unit [DRTU]) at
the remote site.
To perform testing, the central equipment informs the Host about which loop
is going to be tested. The Host selects the corresponding HUB, Line card and
UMP and sends the commands needed to create a connection between the Test
Unit testing bus and the Loop Under Test.
To begin a test on an odd-numbered line drawer, a relay activates to disconnect
the UMP that connects to the even-numbered line drawers and enables the
external test device to connect to the correct UMP. The UMP connects to a
metallic bus back to the MTM in the host over external tip, external ring, and
sleeve connections to the MDF.
The Host or the central equipment dials the corresponding Test Unit. Then the
central equipment sends the command to perform the measurement. The Test
Unit returns the measurement results to the central equipment and all the above
mentioned connections are disconnected.
The following diagrams show this testing configuration.
DMS-100 Family NA100 Star Remote System XPM15 and up