GPS Reflected Signal Analysis using Software Receiver

A reflected GPS signal is normally considered as noise (multipath). However, we believe that a reflected signal contains information about the reflecting object. Though, this information may not be useful for accurate position computation, it may help us to identify the reflecting object itself, which is a type of remote sensing. Besides, by measuring the time delay of the reflected signal, it is possible to estimate the extra path length the reflected signal has to travel. Hence, in general, the analysis of reflected signal can be used for two broad categories of altimetry and remote sensing. However, this type of analysis is rather limited with current commercial GPS receivers. We are in the process of developing a software-based GPS receiver that is capable of reflected signal analysis for remote sensing purpose. The receiver consists of multi-polarization (RHCP and LHCP) array of GPS antennas, front-end device, a PC and necessary software for signal processing. In this paper, we discuss about the system architecture and algorithms, results of reflected signal analysis observed at different places in different conditions and antenna types. Finally, we will discuss the possibility of the system for remote sensing applications using GPS signal.