Comtech EF Data SDM-2020, Installation And Operation Manual

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SDM-2020 Satellite Demodulator Data Interfaces
Rev.3 A–59
A.7.3 Interface Specifications
The following sections describe the detailed requirements for the SMPTE-310M data
interface.
A.7.3.1 Specification Summary
Refer to Table A-34 for SMPTE-310M specifications.
Table A-34. SMPTE-310M Specification Summary
Video Interface (Terrestrial)
Signal Type Biphase mark coded synchronous serial data per SMPTE-310M and TM
1449.
Connector Type
75
Ω
BNC.
Interface and Connector
Impedance
Resistive 75
Ω
unbalanced, per SMPTE-310M.
TX and RX Signal Level
800 mV
±
10% per SPMTE-310M.
DC Offset
0.0 V
±
0.5 V.
Rise And Fall Times The rise and fall times, determined between the 20 and 80% amplitude
points shall be within 0.4 ns and 5.0 ns and shall not differ by more than
1.6 ns, per SMPTE-310M.
Overshoot 10% maximum (on both rising and falling edges) per SPMTE-310M.
Receiver Sensitivity The receiver shall operate with up to 3 dB amplitude loss at 1/2 the
interface clock.
Return Loss 30 dB minimum, 100 kHz to the interface clock frequency per
SMPTE-310M.
ATSC Data Rate 8VSB: 19.392 658 46 Mbit/s = (4.5 E6) x (684/286) x (564/313)
Clock Accuracy
Programmed data rate
±
100 ppm.
Clock Jitter, Drift And
Wander The interface clock frequency error (drift limit) shall not exceed
±
2.8 ppm.
The rate of frequency change (drift rate) shall not exceed 0.028 ppm/s.
The jitter in the timing of the interface signal transitions shall not exceed
2 ns p-p, measured over a bandwidth of 1 Hz to 1/100 of the interface
clock frequency.
Cable Length, Typical RG59 180 meters (591 feet)
Belden 8281 250 meters (820 feet)
Auxiliary Function Port
Signals DF (Demodulator Fault, open-collector output).
CD (Demodulator Carrier Detect, TTL output).
RTS (Modulator Control, TTL input)
Connector 9 Pin D, female.