Comtech EF Data SDM-9000 - Manual (Page 25)

SDM-9000 Satellite Modem Introduction
Rev. 4 1–3
The modem provides high performance with:
•
Narrow occupied bandwidth
•
Automatic signal acquisition
•
High flexibility
•
Extensive online monitoring circuits
The modem interfaces between Single Channel Per Carrier (SCPC) fixed-rate terminal
equipment that operates within the following specifications:
•
Data rate of 6.0 to 51.84 Mbit/s
•
Symbol rate of 1.7 to 37.5 Ms/s
•
Configured to add overhead and framing to the data
The 51.84 Mbit/s data rate is defined by STS-1 (Sonnet specifications).
1.1.1 Nyquist Filter Printed Circuit Boards
The modem features include a Nyquist filter Printed Circuit Board (PCB) for enabling
the user to change data rates at the modulator or demodulator. The modem supports up to
four channels at the following data rate and modulation type combinations:
Data Rates 6.0 to 51.84 Mbit/s Comments
Modulation Types QPSK 1/2 Rate
QPSK 3/4 Rate
QPSK 7/8 Rate
8PSK 2/3 Rate
8PSK 5/6 Rate
16QAM 3/4 Rate
16QAM 7/8 Rate
Optional
Optional
Optional
Optional
Data rate information is automatically recovered from the filter module upon system
power-up or initialization. The installed interface, modulator, and demodulator must be
compatible with the installed filters for proper modem operation. The filters can be
installed in the factory or field.
Refer to Chapter 3 for information about modem configuration.