Satellite DAB

Abstract

Service requirements for digital audio broadcasting (DAB) from satellites are presented, and plans for implementing such systems in various countries are surveyed. Technical and economic constraints, including satellite transmitter power, frequencies of operation, transmission bandwidth, service interference and user receiver design are discussed particularly for DAB systems employing mobile receiving terminals where transmission outage from blockage and multipath fading must be addressed. Transmission performance improvement techniques such as spatial diversity, modulation, coding and interleaving are described. An illustration of a specific satellite DAB system design is presented to show the technical and economic feasibility of such new services.

Technical advances in digital audio radio broadcasting

“…The satellite takes this signal and shifts the up-link frequency to the proper downlink frequency, applies power amplification, and directs the signal to its designed footprint/service area. The signals are received by both stationary and mobile receivers within this area and are processed to retrieve the audio baseband signals (see [110]). To make uninterrupted broadcast reception possible, it is necessary to maintain a line of sight (LOS) with the satellite.…”

“…Since its main beam has to see the satellite as the mobile platform turns and moves, the most economic solution is the use of a low-gain antenna with toroidal beam shapes. This shape allows constant gain in the azimuthal plane and directive gain in the elevation plane [110].…”

Passive geosynchronous SAR system reusing backscattered digital audio broadcasting signals

“…As in the DAB system proposed in [2], we hypothesize that the nominal transmitter EIRP is 57dB w on the B s = 4MHz system bandwidth (that corresponds to a power on the ground of about P g = −171dB w /m 2 /Hz ), the transmitter beam center is supposed to be at latitude 0 0 (different latitudes can also be considered; then a squinted bistatic system should be dealt with, not to be discussed here). The central frequency is 1.5GHz and σ 0 = −18 dB.…”

“…As hundreds of digital communications satellite channels (i.e. television, Digital Audio Broadcasting (DAB) and personal communications) will be available in the near future [1] [2], it is interesting to evaluate the feasibility of a bistatic (parasitic) Synthetic Aperture Radar (SAR) system [3] based upon a geostationary transmitter and a geosynchronous receiver [4]. With the envisaged levels of Effective Irradiated Power (EIRP), it is possible to create useful images of the terrain at a continental scale.…”