Overview

An SSB transmitter system may contain several functional elements, as shown in Figure 5.1. These include a data terminal, remote control unit, exciter, power amplifier, antenna coupler, and antenna. More elaborate systems may also include switching units, RF output bandpass filters, or control processors. The essential elements, though, are the exciter, power amplifier, and antenna. They may be separate or combined into a single unit, as in a packset, for example.

Figure 5.1: Typical SSB transmitter system.

The exciter is a key component of this system and performs several important functions. It translates one or more baseband input signals to the desired output frequency and drives the power amplifier at the proper level. It provides different emission modes such as CW or FSK. Usually it coordinates gain setting and tune cycle operations of the transmitter. It also controls such parameters as bandwidth, distortion, frequency stability, and spurious emissions.

This chapter discusses the performance requirements of an exciter, how its component parts are assembled in an architecture that meets the requirements, and how it performs the necessary functions.

A transceiver may be defined as an exciter and receiver combined in one functional unit. In applications where size is at a premium, such as in airborne or other mobile equipment, a transceiver configuration provides the most efficient use of available space. Transceiver design will also be discussed.

5.1 SSB Exciter Output Signal Requirements

Ideally the RF output from an SSB exciter...