PairGain PG-Flex, Руководство пользователя

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PG-Flex System Overview
10
RT Channel Units
Channel units provide the interface between subscriber services (POTS, ISDN) and the PG-Flex
system’s internal pulse code modulation (PCM) bus. The RT channel units must be installed in the
same relative slot positions as the channel units on the CO-end of a PG-Flex system.
The RT channel units provide the following features:
• 64 kbps A-Law PCM encoding
• applies ringing voltage
• generates forward disconnect
• generates metering tones (12 kHz, 16 kHz)
• detects an off-hook or ring-tip condition
• connects a subscriber loop to a metallic test pair
• protects against secondary surges
A status LED is associated with each line to indicate whether the line is off-hook, idle, ringing, or
being tested. A common fault LED indicates a general fault has been detected on the unit
(Figure 7). Metallic test access connections to a specific line circuit are made through the Craft port
or by the CO switch applying the appropriate voltages on the subscriber line.
Figure 7. RT Channel Unit Block Diagram