Receiver IC-set for digital satellite system

Abstract

A new digital satellite radio broadcast service has been introduced using the L-band frequencies that are allocated for digital audio broadcasting by the WARC-92 conference. The coverage area includes Africa, and most parts of Asia and South America. This direct to home (DTH) service uses digital QPSK-modulation combined with convolutional and Reed Solomon forward error correction (FEC). The sophisticated MPEG 2.5 layer 3 audio data reduction scheme ensures a high audio signal quality, even at low bit rates. A new chip set has been developed for the demodulation and decoding of the signals transmitted from the geostationary satellites. The chip set has been designed to act as the core element of future radios that will be capable to receive that signal. All required digital and analog parts from the IF-A/D converter to headphone/loudspeaker amplifiers are provided on chip. In spite of tight cost constraints, the design was uncompromising with respect to signal reception and audio signal quality. The high error protection capabilities of the system theoretically predicts possible reception under carrier to noise (C/N) conditions where the classical carrier and timing recovery algorithms fail. For this reason a new fast and robust synchronization algorithm has been developed that ensures reliable radio reception even at a poor C/N ratio of the input signal. Starting with a short overview of the technical parameters of the digital satellite radio system and the basic features of future receivers this paper presents the building blocks and some underlying algorithms of the newly developed chip set.