Snow depth sensing using the GPS L2C signal with a dipole antenna

Prior research has shown that the currently deployed geodetic global positioning system (GPS) stations can be used to measure snow depth in an area around the antenna installation via GPS interferometric reflectometry (GPS-IR). Although such a technique provides the advantages of large spatial coverage and high temporal measurement sampling, there are also drawbacks in using geodetic equipment for this application. The geodetic antenna is costly and designed to mitigate the multipath signal, while for snow depth sensing, the reflective component contains the desired information regarding the environment. In this paper, the authors reviewed the principles of snow depth sensing via GPS-IR and show that the horizontally polarized electromagnetic wave is the desired signal for this application. A customized dipole antenna, which was designed to be horizontally polarized by properly adjusting its orientation, was built and evaluated in an experiment carried out at Table Mountain, Boulder, Colorado, during early February 2012. In this experiment, a universal software radio peripheral (USRP) is used to collect the raw data and a software-defined receiver (SDR) for L2C signal is used for data processing. Data and results from this dipole antenna/SDR implementation are compared with those from the geodetic GPS station and show an improvement for snow depth estimation.