Detection and Processing of bistatically reflected GPS signals from
low Earth orbit for the purpose of ocean remote sensing
IEEE Transactions on Geoscience and Remote Sensing, 43 (6):
1229-1241 (2005)DOI: 10.1109/TGRS.2005.845643
Abstract
We will show that ocean-reflected signals from the global positioning
system (GPS) navigation satellite constellation can be detected from
a low-earth orbiting satellite and that these signals show rough
correlation with independent measurements of the sea winds. We will
present waveforms of ocean-reflected GPS signals that have been detected
using the experiment onboard the United Kingdom's Disaster Monitoring
Constellation satellite and describe the processing methods used
to obtain their delay and Doppler power distributions. The GPS bistatic
radar experiment has made several raw data collections, and reflected
GPS signals have been found on all attempts. The down linked data
from an experiment has undergone extensive processing, and ocean-scattered
signals have been mapped across a wide range of delay and Doppler
space revealing characteristics which are known to be related to
geophysical parameters such as surface roughness and wind speed.
Here we will discuss the effects of integration time, reflection
incidence angle and examine several delay-Doppler signal maps. The
signals detected have been found to be in general agreement with
an existing model (based on geometric optics) and with limited independent
measurements of sea winds; a brief comparison is presented here.
These results demonstrate that the concept of using bistatically
reflected global navigation satellite systems signals from low earth
orbit is a viable means of ocean remote sensing.