Detection of the Multipath Effect in the ING2 GPS Station with a New Developed Software

The multipath effect is one of the major error sources affecting the Global Positioning System (GPS) observables both in static and kinematic precise positioning and navigation. This effect occurs when satellite’s signal is reflected from the ground or other objects in the vicinity of the antenna and it is received as secondary path which is superimposed on the direct-path signal. The effect of the multipath on the GPS observables can cause longer propagation time and significant distortion of the signal waveform amplitude and phase. By using a Differential GPS (DGPS) it is possible to reduce the clock, ephemeris, ionospheric and tropospheric errors to centimeter level. Afterwards the multipath effect can be considered the main error source in GPS measurements in a meters level. A GPS data analysis software (S/W) has been developed at the Radio Science Laboratory of the II Faculty of Engineering of the University of Bologna, with the purpose of the zenith wet path delay estimation due to the Earth troposphere based on the double difference techniques. Since the Earth troposphere delay estimation has been detected and some positive tests has been undertaken, the S/W has been used for the detection of the multipath effect in the stations involved in the analysis. A preliminary test has been undertaken with the GPS station installed in the Radio Science Laboratory of the University of Bologna, named ING2.