The BERT-20E1 also provides a 75
Ω
EXT CLOCK IN port which accepts
a 2 MHz clock source complying with ITU-T G.703 Section 10
(Reference 1). Normally, the access point for in-service testing is
available on the digital distribution frame (DDF). A less common
alternative is a monitor point on the front panel of a network element
(NE).
Connecting to a Protected Monitor Port
When conducting out-of-service testing, choose TERM (terminated)
mode as your receive interface.
There are two types of electrical access ports for in-service testing:
■
Protected monitor ports.
■
Unprotected monitor ports.
For protected monitor ports, the access point usually has built-in, fixed
attenuation. Typically, this gives a test signal 30/26/20dB down on the
traffic signal. Select MON (monitor) as your receive interface termination.
Next choose the appropriate MONITOR GAIN from the BERT-20E1’s
AUX menu.
Connecting to a Unprotected Monitor Port
For unprotected monitor ports, choose BRDG (bridged) as your receiver
interface termination. Alternatively, connect a high-impedance
(protective) probe which substitutes for the fixed attenuation of a
protected monitor port and then choose MON (monitor) as the receiver
interface termination. Select MONITOR GAIN from the AUX menu
functions.
CAUTION:
When in MON (monitor) mode, do not connect directly to an
unprotected monitor point. This could damage the BERT-20E1 and could
even cause degradation of performance or complete loss of traffic on a
live channel.
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