PairGain PG-Flex, Руководство пользователя

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Subscriber Drop Testing
103
Subscriber Drop Testing
PG-Flex provides metallic access to the subscriber circuit in support of subscriber drop testing.
Using standard metallic access techniques and equipment, you can access a specific subscriber drop
and have a metallic test path back to the Central Office test equipment.
PG-Flex allows subscriber line test functions on a first-come, first-served basis. Only one line
access function can be established on a single system at a time. When testing in conjunction with
an FPI-729, only one line test per COT Shelf is allowed. In this particular instance, a PGTC test
established on another PG-Flex system within the shelf terminates another line access function in
progress.
To ensure that the test system can identify a carrier channel unit, all channel units incorporate the
appropriate three-terminal dc signature resistances (Table 32) and conform to Bellcore’s
TR-NWT-000057.
Bridging and Breaking
The basic subscriber line access methods are bridging and breaking. The access functions have
been designed primarily with POTS circuits in mind although it works with other 2-wire services,
such as ISDN.
Bridging provides a low impedance connection in parallel across the circuit. Breaking separates the
subscriber connection at the point of interest; providing exclusive access to the line for the attached
test equipment. The metallic access points are reached via the test jack(s) on the FAU-728 alarm
card or the FPI-729 PGTC interface unit.
There are two different ‘Looks’ when providing break-out access to the subscriber line—Looking-
In and Looking-Out. The terms ‘In’ and ‘Out’ are relative to the direction of the Central Office
switch. ‘In’ is the direction toward the switch and ‘Out’ is in the direction of the subscriber.
Only one subscriber circuit in a PG-Flex shelf can be accessed at a time when an FPI-729 List 1
or an FAU-728 List 2 is installed.
If an FAU-728 List 1 is installed, one subscriber circuit in each PG-Flex system can be accessed
simultaneously.
Table 32. COT Channel Unit Signatures
Termination FLC-701, List 2
FLC-703, List 3 All Other COT POTS
Channel Units
Tip-Ring (open) 475 k
Ω
, 1%
Tip-Ground 162 k
Ω
, 1% 332 k
Ω
, 1%
Ring-Ground 162 k
Ω
, 1% (open)