OVERVIEW

In the previous chapters digital modulation techniques which have been used in digital microwave systems are described. Typical performance characteristics of planned and operational M-ary PSK, QAM, and quadrature partial response (QPRS) digital microwave systems are examined. In this chapter, some digital and hybrid microwave systems which do not use these modulation techniques are presented. Among the techniques used are amplitude phase keying (APK), pulse-amplitude modulation-FM (PAM-FM), mininum shift keying (MSK), and PAM vestigial sideband (PAM-VSB). In addition to these dedicated digital radio systems, a number of analog FDM-FM microwave systems have been converted and carry a mixture of analog FDM and digital TDM traffic. These hybrid FM systems, such as the data under voice (DUV), data in voice (DIV), data above voice (DAV), and data above video (DAVID) systems are also described in this chapter.

In Section 8.4 we describe a novel subscriber radio system configuration that uses digital modulation techniques. This system is conceptually similar to single-channel-per-carrier (SCPC) satellite systems and is expected to find applications predominantly in sparsely populated rural areas.

Now, having read this introduction, we hope that it has become clear to you why the word potpourri was chosen for the title of this chapter. A number of microwave systems utilizing a variety of modulation techniques, a wide range of bit rates (64 kb/s to 400 Mb/s), and different system configurations are presented. Due to space limitations, only a short description of these systems is given here. For an in-depth study of...