Development of a Spectrally Efficient, High Speed Modem for Microwave Terrestrial and Satellite Communications

The widespread demand for use of the limited radio spectrum leads to the design of high--speed modems which are spectrally efficient. This paper discusses the current work being undertaken on a DSP based modem supporting data rates ranging from 2 Mbit/sec up to 20 Mbit/sec. 1 INTRODUCTION This paper focuses on the joint development between the University of South Australia and JNS Electronics Pty. Ltd. (Melbourne) of a flexible DSP based modem for high data rate transmission. The need for high data rate transmission poses serious hardware design challenges which will be discussed in various sections of this paper. Due to tight spurious emission specifications existing in Australia for allocated channel bandwidth, the major objective of the modem design is to be as spectrally efficient as possible. This paper outlines various methods used to achieve high spectral efficiency; minimising spurious emissions outside allocated frequency bands of operation. Another objective for this modem is..