Abstract
A filter to separate the effect of multipath in Global Navigation Satellite System (GNSS) signal-to-noise ratio (SNR) data is presented. The filter removes multipath cleanly, and affects neither slowly varying trends (such as tropospheric absorption or variation in satellite range) nor high frequency components (such as ionospheric scintillation), and so is potentially useful in space-weather research. Similarly, the multipath data removed from the input data is minimally distorted, and contains useful information as to the multipath geometry. A method to locate reflecting objects using a form of spectral analysis is described.