Specifications

SDM-650B Satellite Modem Asynchronous Overhead Channel Unit
Rev. 5 F–9
F.3 ASYNC Interface Specifications
Main Channel
Physical Interface MIL-STD-188-144
Factory Option RS-422/-449
V.35
G.703
Data Rates 9.6K, 19.2K, 32 k/bits to 8.448 Mbit/s, in 32 k/bits steps
G.703 Data Rates 1.544 Mbit/s
Jumper Selectable 2.048 Mbit/s
6.312 Mbit/s
8.448 Mbit/s
G.703 Line Code AMI, B8ZS, B6ZS, HDB3
Transmit Clock Reference Internal modem reference or external transmit clock (SCT or
TT)
Jitter Attenuation Per G.703
Pulse Mask Per G.703
Overhead Channel
Overhead Rate 16/15 of main channel
ASYNC Channel Rate (max.) < 1.875% of main channel
ASYNC Channel Interface RS-232-C
2-wire RS-485 half-duplex
4-wire RS-485 full-duplex
Connector 25-pin D on breakout panel
Baud Rates, Asynchronous 110, 150, 300, 600, 1200, 2400, 4800, 9600, 19200,
38400 bit/s
Asynchronous Format 5, 6, 7, or 8 data bits
Even, Odd, or no parity
1 or 2 stop bits (1 or 1.5 for 5 bit)
Pleisiochronous Buffer Specifications
Buffer Size 384 to 262144 bits, in 16-bit steps
Buffer Fill Status Monitored accurate to ± 1%
Buffer Centering Automatic or Manual
Buffer Clock Reference Transmit
Internal (10
-5
Stability)
External
Receive (Buffer Bypass)
External Clock Amplitude Differential, 0.5 to 5 Vp-p
Common Mode, 0 to 5 VDC
External Clock Frequency 256 to 2048 kHz, in 64 kHz steps
External Clock Impedance 100Ω
External Clock Input Type Sine or square wave
50%, ± 10%