3 specification – Comtech EF Data SDM-650B User Manual
Page 55
SDM-650B Satellite Modem
Configuration
Rev. 5
3–13
3.2.1.3 Specification
Circuit Supported
SD, ST, TT, RD, RT, DM, RR, MOD, FAULT,
DEMOD FAULT, MC.
Amplitude (RD, RT, ST, DM, RR)
4,
±
2V differential into 100
Ω
.
DC Offset (RD, RT, ST, DM, RR)
0,
±
0.4V.
Impedance (RD, RT, ST, DM, RR)
Less than 100
Ω
, differential.
Impedance (SD, TT, MC)
100,
±
20
Ω
, differential.
Polarity
True when B positive wrt A.
False when A positive wrt B.
Phasing (RD, RT)
False to True transition of RT nominally in
center of RD data bit.
Symmetry (ST, TT, RT)
50%,
±
5%.
Frequency Stability (ST)
±
100 PPM.
Modulator Fault
Open collector output.
15V max.
20 mA max. current sink.
Fault is open circuit.
Demodulator Fault
Open collector output.
15V max.
20 mA max. current sink.
Fault is open circuit.