Software Radio Processing of Sampled Bistatic Reflected GPS Data

The software receiver approach to reflected GPS signal processing offers several advantages over delay-mapping receivers which employ real time processing with hardware correlators. These include the ability to replay the same segment of data using different integration times, or correlator spacing, and the flexibility of large arrays of correlators to map the complete glistening surface of all visible satellites. The disadvantage of software receivers is the need to record sampled data at higher than the Nyquist frequency, which results in the generation of a large volume of data. These large data sets will consequently require substantial computer processing requirements. A software receiver toolbox is being developed at Purdue University, in the MATLAB language, for the post-processing and visualization of reflected GPS waveforms. Application of this toolbox to airborne data, using the C/A code, will be demonstrated. Additionally, the interface of this post-processed data with retrieval algorithms developed for DMR data will be discussed. Use of the 272 processor IBM SP supercomputer for the reduction of larger data sets will also be described.