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5−
11
5.4214 Monitor
Jack
A front panel jack allows the recovered signal to be monitored by any T1/E1
test set with a monitor input (-20 dB referenced to the input).
5.4215 One-wire
Interface
The one-wire interface allows communication of data between the T1/E1 input
card and the 54550 Information Management Card.
5.4216 Power
An on-card power converter provides the necessary circuit voltages from the
diode-combined A and B -48 volt battery supplies. The on-card fuse, if it
blows, lights the red FAIL LED and provides battery to the Fuse Alarm bus
connecting to pin 10 on the backplane terminal strip TB1.
5.5 Model 54522 Stratum 3E/LNC Track and Hold Clock Card
5.5010 There are two 54522 track and hold cards, one active and one standby, in a
redundant Stratum 3E/LNC (Local Node Clock) system. The 54522-5 supports
the AB input architecture. The AA input architecture is not supported.
NOTE:
Both track and hold cards in a system must support the same input architecture, either
AA or AB. See Appendix A.
5.51 Functions
5.5110 The Model 54522 clock card performs the following functions:
a. Accepts one of two 1.544 MHz clock signals and provides a smoothed and
jitter free signal to the output cards from a synthesizer tracking the input
reference.
b. Monitors reference input for framing (T1/E1) and cyclic redundancy check
sum (CRC) errors. An out-of-specification input signal forces the card to
hold to the last known reference, with a drift of less than 5 x 10
-9
in 24
hours. The last known reference value is stored in EEPROM for use as an
initial value on the next power-up cycle. The signal to the output cards is
continuous (no phase hits) during any switch from track to hold.
Frequency and phase corrections occur over periods of about 3000
seconds. A fast ACQUIRE state reduces this to 100 seconds for power-up
and 300 seconds when returning from the HOLD state.
c. Accepts an external 5 or 10 MHz signal from a high stability timing source
such as a GPS receiver, cesium clock, or similar mechanism. The
external signal is selected as a tracking reference through user commands
to the 54550 Information Management Card.
d. Supplies monitoring and alarm information to the 54550 Information
