Specification; Asynchronous Overhead Interface; Functional Description - Comtech EF Data SDM-650B Installation And Operation Manual

SDM-650B Satellite Modem

3.2.4.9 Specification

Pairs
Circuits Supported
Data Rate
Pulse Width (RD)
Line Code
RD Amplitude
SD Amplitude
Jitter Attenuation (SD)
Modulator Fault
Demodulator Fault

3.2.5 Asynchronous Overhead Interface

3.2.5.1 Functional Description

The asynchronous overhead interface module consists of three subassemblies:
•
•
•
The connector board provides the physical interface using a 50-pin D connector.
The terrestrial interface contains all circuitry required for G.703, RS-422, MIL-STD-188,
and V.35 type interfaces for synchronous data, and RS-232-C and RS-485 type interfaces
for asynchronous data.
The data processor contains all circuitry required for multiplexing the synchronous and
asynchronous data streams, as well as data rate synthesizers and the optional
plesiochronous buffer.
Refer to Figure 3-12 for a block diagram of the asynchronous overhead interface.
Rev. 5
Connector board is AS/1328.
Data processor board is AS/1289.
Terrestrial interface is AS/1311.
Dash # Interface
1311-1 RS-422 1311-4
1311-2 V.35 1311-5
1311-3 G.703 1311-6
Symmetrical pair, coaxial pair optional.
SD, RD, MOD FAULT, DEMOD FAULT.
2.048 Mbit/s, ± 50 PPM.
244, ± 25 ns.
AMI or HDB3 (selectable).
3.00, ± 0.3V pk into a 120Ω termination.
3, ± 1.5V pk into a 100Ω termination.
Exceeds CCITT G.823, specification for 2048 kbit/s.
Open collector output.
15V max.
20 mA current sink.
Fault is open circuit.
Open collector output.
15V max.
20 mA current sink.
Fault is open circuit.
With AUPC
Configuration
3–31