4
61433105L1-5F
Section 61433105L1, Issue 6
Span Power
Span powering is accomplished using -130 VDC
measured from Tip to Ring. Voltage measured from
Tip to GND should be -130 VDC or less depending on
voltmeter impedance. Voltage from Ring to GND
should indicate approximately 0 V.
Synchronization and LED Indication
The DDS-DP and DDS-R typically require 30 to 90
seconds to achieve synchronization. Once
synchronized, the SYNC LOSS indicator LED will
turn OFF. If synchronization cannot be achieved,
check the T/R pair for open or short circuit conditions
or load coils. See
Table 3
for LED indications.
Figure 5. DDS-DP Bidirectional Loopback
Test
Unit
DDS-R
Series 5
DDS-DP
Data
Pass-Through
Bidirectional
loopback
Figure 4. OCU Loopback at the DDS-DP
Series 5
DDS-DP
OCU
Bidirectional
loopback
Customer
Intra-office
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4. TESTING
Testing for the DDS-DP is accomplished using the
same test procedures for 4-wire OCU and OCU DP
units.
NOTE
If 64 kbps is selected, the unit will only respond to
latching loopback sequences. Alternating
sequences are not valid at this rate.
DDS DP Bidirectional Loopback Support
The DDS DP will execute a bidirectional loopback
when performing an OCU loopback at the DDS-DP as
shown in
Figure 4
. During a bidirectional loopback
the DDS-R enables test data to pass through the
4-wire interface to the customer premises. This
allows a standard portable test set at the customer
premises to verify the integrity of both the 4-wire and
2-wire loops by transmitting a test pattern to the DDS
DP and examining the returning data for
synchronization and errors. A bidirectional loopback
and pass through is shown in
Figure 5
. During a
bidirectional loopback initiated at the DDS DP the
DDS-R LBK LED will flash. Refer to remote unit
documentation for LED descriptions.
