Comtech EF Data SNM-1001 - Manual (Page 32)

Rev. 1 4–1
4
Chapter 4.
THEORY OF OPERATION
This chapter describes the theory of operation for the various PCBs in the modem.
4.1 Modulator
The modem modulator creates a QPSK modulated carrier within the 50 to 180 MHz
range from the digital data stream provided by the interface section.
The following subsections make up the modulator:
•
Scrambler
•
Convolutional encoder
•
I/Q Nyquist filters
•
Modulator
•
Output amplifier
•
RF synthesizer
•
SCT synthesizer
Modulator jumper settings are shown in Table 4-1 .
A block diagram of the modulator is shown in Figure 4-1.