Automotive FM Diversity Systems, Part II: Analog Systems 2007-01-1732
This paper represents Part II of a three part series on automotive FM diversity systems. Part I (2007-01-1731) focuses on a review of propagation channel modeling and multipath fading. Part II deals with analog diversity systems which have been developed to combat the effects of this fading in an FM broadcast signal. Part III (2007-01-1734) discusses new FM diversity system designs that have been implemented in digital signal processors (DSP's).
Analog automotive diversity systems have been in production for more than 20 years. The main purpose of a diversity system is to reduce the degraded reception performance caused by multipath propagation, mainly, the flat (amplitude) fading of the carrier. This is often accomplished by the use of two or more uncorrelated receiving antennas. This paper investigates the performance of analog implementations of Phase Aligning Systems (PAS) and Switched Antenna diversity systems in flat fading conditions and frequency selective multipath (long-delay) situation.