Instruction manual

FUNCTIONAL DESCRIPTION
NPE 0
NPE 1
ON-BOARD
MICROPROCESSOR
Figure 3-11.
DID Trunk (TN753) Unique Circuitry
Ground Start Trunk (ZTN76j
TO
CENTRAL
OFFICE
The Ground Start Trunk CP (Figure 3-12) interfaces eight central office trunks and the TDM
bus. The Ground Start Trunk has the following unique circuitry:
● Ground Detector Circuit
The ground detector circuit determines if ground has been applied to the tip lead for
incoming seizure. It also senses tip ground on outgoing seizure indicating dial tone is
present. One ground sensor is used for each port circuit. Input for the ground
sensor comes from the port circuit as an analog current to the -48 volt dc supply.
The output of the ground sensor is a port control point to the port I/O circuit.
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