Comtech EF Data SDM-650B - Manual (Page 61)

SDM-650B Satellite Modem Configuration
Rev. 5 3–19
3.2.2.3 Specification
Circuit Supported SD, SCT, SCTE, RD, SCR, DSR, RLSD, MOD,
FAULT, DEMOD FAULT, MC.
Amplitude (RD, SCR, SCT, SD, SCTE) 0.55V pk, ± 20% differential, into 100 Ω .
Amplitude (CTS, DSR, RLSD) 10, ± 5V into 5000, ± 2000 Ω .
Impedance (RD, SCR, SCT) 100, ± 20 Ω , differential.
Impedance (SD, SCTE) 100, ± 10 Ω , differential.
Impedance (RTS) 5000, ± 2000 Ω , < 2500 pF.
DC Offset (RD, SCR, SCT) ± 0.6V max., 1000 Ω termination to ground.
Polarity (SD, SCT, SCTE, RD, SCR) True when B positive wrt A.
False when A positive wrt B.
Polarity (RTS, CTS, DSR, RLSD) True when < -3V wrt ground.
False when > +3V wrt ground.
Phasing (SCTE, SCR) False to True transition nominally in center of data
bit.
Symmetry (SCT, SCTE, SCR) 50%, ± 5%.
Frequency Stability (SCT) ± 100 PPM.
Modulator Fault Open collector output.
15V max.
20 mA current sink max.
Fault is open circuit.
Demodulator Fault Open collector output.
15V max.
20 mA current sink max.
Fault is open circuit.