Automotive antenna diversity system for satellite radio with high phase accuracy in low SNR-scenarios

Abstract

For a fast scan-phase satellite radio antenna diversity system a noise correction method is presented for a significant improvement of audio availability at low signal-to-noise ratio (SNR) conditions. An error analysis of the level and phase detection within the diversity system in the presence of noise leads to a correction method based on a priori knowledge of the system's noise floor. This method is described and applied in a hardware example of a satellite digital audio radio services antenna diversity circuit for fast fading conditions. Test drives, which have been performed in real fading scenarios, are described and results are analyzed statistically. Simulations of the scan-phase antenna diversity system show higher signal amplitudes and availabilities. Measurement results of dislocated antennas as well as of a diversity antenna set on a single mounting position are presented. A comparison of a diversity system with noise correction, the same system without noise correction, and a single antenna system with each other is performed. Using this new method in fast multipath fading driving scenarios underneath dense foliage with a low SNR of the antenna signals, a reduction in audio mute time by one order of magnitude compared with single antenna systems is achieved with the diversity system.

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“…However, these approaches do not guarantee protection from fading when signals annihilate. Alternatively, diversity combining is possible with phase compensation, which is the technique of shifting signal phases such that shifted signals align and sum constructively 26,27 . Phase shifting reduces fading and increases the signal-to-noise of the received signal, and it provides cues for localizing a transmitter 28,29 .…”