The application of space diversity for digital audio broadcasting

Numerous investigations on the minimum required fieldstrength for digital audio broadcasting (DAB) reception have been made. The maximum symbol error rate (SER) of the unprotected channel which guarantees good signal quality at the receiver output has been determined, too. Consequently, many coverage parameters are already fixed. To improve and enlarge the coverage areas new ideas are required, e.g. the introduction of space diversity systems at the receiver. In this paper diversity systems with different combiner techniques are investigated. Especially for the 1.5 GHz range with 20 cm wavelength, the dimensions of a common car exceeds several wavelengths. For that reason space diversity appears to improve the signal quality significantly. The obtained results at 230 MHz and 1.5 GHz show that the minimum required fieldstrength decreases drastically due to the diversity technique used. A new "SER-combiner" is presented which allows much higher values of SERs on the unprotected propagation channel for good signal quality compared to a receiver without diversity. Hence, space diversity techniques become an important topic for mobile DAB reception.