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Technical Characteristics
Item
Electrical (cont)
Network and Cascade transmitter
Frequency
Pulse amplitude — with surge
protection current.
Unbalance in height of adjacent
negative and positive pulses
Width of output pulse (half
amplitude)
Unbalance in width of positive and
negative pulses
Time between two consecutive
pulses of opposite polarity
Maximum rise or falling time
Overshoot at trailing edge of pulse
Line Build-Out
Timing source
Network and Cascade receiver
Operating range
Input impedance
Jitter tolerance
Longitudinal balance
Transmitter
Pre-equalization
Impedance
Receiver
Impedance
Channel port (cust equip) interface
Standard
Optional
Physical interface
A-2
1,544,000 bps ± 75 bps
2.40 to 3.60 V at 60°F — may vary over a cycle of 60 Hz
200 mV (maximum)
324 nsec ± 45 nsec
20 nsec (maximum)
648 nsec ± 15 nsec (measured at half amplitude point of
leading edges)
100 nsec
10% to 30% of pulse amplitude
0, 7.5, or 15 dB (selectable or automatic) at 772 kHz
Internal clock, external clock, slave (received timing
loopback)
0 to -32 dB of cable loss at 772 kHz
100¾
Conforms to specifications defined in AT&T PUB 62411,
December 1988
35 dB from 50 to 1500 kHz
0 to 655 feet of line length
100¾
100¾
ITU-T V.35-compatible synchronous serial data port
EIA-530 compatible synchronous serial data port
DB25S (25-pin female subminiature-D connector)
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Specification
076R155-000
Issue 7
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