Basic System Configuration Guide System Management
Edition: 01 3HE 11010 AAAC TQZZA 221
Each clear channel DS3/E3 port on a 4-port DS3/E3 Adapter card can be
independently configured to be loop-timed, node-timed, or differential-timed. When
a DS3 port is channelized, each DS1 or E1 channel can be independently configured
to be loop-timed, node-timed, or differential-timed (differential timing on DS1/E1
channels is supported only on the first three ports of the card). When not configured
for differential timing, a DS3/E3 port can be configured to be a timing source for the
node.
6.4.1 External Timing Mode
The external input and output timing ports are located on the CSM on the
7705 SAR-8 and directly on the 7705 SAR-H and 7705 SAR-M (all variants). The
7705 SAR-A, 7705 SAR-Ax, and 7705 SAR-X have an external timing input port
only, located on their faceplates. The external input timing port allows the SSU to be
synchronized to an external timing reference. The external output timing port
provides a synchronization output signal from the 7705 SAR to an external device.
These external timing references typically would come from a GNSS, Building
Integrated Timing System (BITS), or the external output timing ports from other
telecom equipment.
The timing ports can be configured for the following:
• 2.048 MHz G.703 section 13 signal
• 5 MHz sine wave (not available on 7705 SAR-8 CSMv2)
• 10 MHz sine wave
On the 7705 SAR-18, the BITS ports 1 and 2 can be configured for the following:
• 2.048 MHz G.703 section 13 signal
• T1 (ESF or SF)
• E1 (PCM30CRC or PCM31CRC)
When redundant CSMs are used on the 7705 SAR-8, the external synchronization
inputs in each CSM must come from the same synchronization source; that is, you
cannot select each input of the two CSMs as two of the three timing references. A Y-
cable can be used to connect to a single reference connector. The synchronization
output on each CSM is clocked by its own SSU clock.
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