A Study of Ground-Based Bistatic Radar for the Validation of Satellite Products

Providing reliable and timely access to environmental information from satellites is a critical function and need at the National Oceanographic and Atmospheric Administration (NOAA), especially for numerical weather predictions. Innovations in this sector are experimenting with new data collection methods, enhancing data quality by reducing Radio Frequency Interference (RFI), and developing new methods for measuring environmental variables. Ground-based bistatic radars using Software Defined Radios (SDRs) are being developed to detect and utilize Signals of Opportunity (SOOP) to measure variables such as sea level rise, ocean surface wind speeds or soil moisture, or to reduce the noise of a signal, to validate satellite products. For instance, GNSS Reflectometry is a method used in both satellite and ground-based observations to monitor the Earth. In this study, a rotating GNSS antenna is used to separate the reflected signal from the direct GNSS signal, to support the validation of satellite measurements over water and land. Open source software, such as RTKLIB and GNSS-SDRLIB, were used to receive and process the raw I/Q data. This new and active research area has a great future for the improvement of satellite data collection, processing and validation, especially for the purposes of enhancing our understanding and predictions of our changing environment. This study will help validate products that retrieve and analyze data from satellites in new and innovative ways, supporting current and future satellite missions like CYGNSS and SNOOPI.