8.1 Introduction

Single-sideband radio communication equipment has traditionally been designed using analog signal processing techniques and circuitry. In the past, the inherent advantages offered by a digital implementation were offset by the higher cost and greater power dissipation of the digital hardware. The limited dynamic range of available analog-to-digital (A/D) converters and sample-and-hold (S/H) devices also prevented the digital implementation from realizing its full potential. The advent of high-speed, low-cost digital signal processing (DSP) devices has changed all that.

Over the past 10 years, microprocessor technology has produced several generations of highly integrated DSP chips primarily targeted at the telecommunications industry, but aptly suited for SSB radio communication applications. During this same period, A/D converter manufacturers have made the transition from technology that was directed mostly at the data acquisition market to the DSP market. The current generation of highly linear, sampling A/D converters, combined with techniques such as bandpass sampling, are now making digital radio equipment design the architecture of choice.

This chapter will discuss SSB digital receiver and exciter concepts, algorithms, and architectures that primarily utilize IF bandpass sampling techniques. Additional discussions will center on critical digital receiver/exciter design considerations and on DSP device characteristics that set or limit the performance of a particular design.

There are several key concepts that are used in digital SSB radio design. Since they are essential to understanding the radio implementations to follow, we shall briefly review them. It is not the purpose here to provide a general treatment...