Measured results of quasi-zenith satellite visibility and its time delayed diversity (TDD) system characteristics

The paper deals with the time delayed diversity (TDD) system characteristics for a quasi-zenith satellite system measured using GPS (Global Positioning System) satellites. To design a digital mobile broadcast satellite system with the TDD system, it must estimate the characteristics of attenuation by urban buildings, electrical light poles, trees, etc. Signal data from southern orbital arc GPS satellites with elevation angles from 40/spl deg/ to 80/spl deg/ are used for propagation characteristics measurements, rather than from actual geostationary satellite orbit (GSO) satellites. To overcome urban signal attenuation, the TDD system is applied for GSO satellites and quasi-zenith satellite systems and TDD characteristics are examined by processing measured GPS data.