Specifications

SDM-309B Satellite Modem External Channel Unit
MN/U-SDM309B Rev. # C-C–21
2.2.2 Connector Pinouts
The V.35 interface is provided on the industry standard 34 pin block connector
accessible from the rear panel of the modem. Screw locks are provided for mechanical
security of the mating connector.
Signal Function Name Pin Number
SIGNAL GROUND SG A,B
SEND DATA SD-A
SD-B
P
S
SERIAL CLOCK TRANSMIT SCT-A
SCT-B
Y
(AA)
RECEIVE DATA RD-A
RD-B
R
T
REQUEST TO SEND RTS C
SERIAL CLOCK RECEIVE SCR-A
SCR-B
V
X
CLEAR TO SEND CTS D
DATA SET READY DSR E
RECEIVE LINE SIGNAL DETECT RLSD F
SERIAL CLOCK TRANSMIT EXT. SCTE-A
SCTE-B
U
W
MODULATOR FAULT --- (MM) m
DEMODULATOR FAULT --- (NN) n
MASTER CLOCK
(INPUT)
MC-A
MC-B
(CC) c
(DD) d
2.2.3 Specification
Circuit Supported SD, SCT, SCTE, RD, SCR, DSR, RLSD,
MOD, FAULT, DEMOD FAULT, MC
Amplitude (RD,SCR,SCT,SD,SCTE)
.55 V pk ± 20% differential, into 100 !
Amplitude (CTS,DSR,RLSD)
10 ± 5 V into 5000 ± 2000 !
Impedance (RD,SCR,SCT)
100 ± 20 !, differential
Impedance (SD,SCTE)
100 ± 10 !, differential
Impedance (RTS)
5000 ± 2000 !, <2500 pf
DC Offset (RD,SCR,SCT) ± .6 V max, 1000 ohm 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
15 V max
20 mA current sink max
Fault is open circuit
Demodulator Fault Open collector output
15 V max
20 mA current sink max
Fault is open circuit