Coastal Altimetry Using Ku/Ka-Bands Signals of Opportunity: Results From A Recent Experiment at Platform Harvest
Event: 2017 Ocean Surface Topography Science Team Meeting
Session: Advances in coastal altimetry: measurement techniques, science applications and synergy with in situ and models
Presentation type: Type Poster
Contribution: PDF file
Over the last two decades, ocean altimetry using signals of opportunity (SoOp) has been demonstrated using transmission from the Global Navigation Satellite System (GNSS). Recently, techniques first developed for GNSS have been expanded to digital communication signals with the promise that the wider bandwidth and higher power would enable sea surface height (SSH) retrievals at a scientifically useful precision.
A reflectometry experiment was conducted at Platform Harvest (Jason-2 calibration and validation site) in July, 2017. Direct broadcast satellite (DBS) transmissions in Ka- and Ku-bands, from a commercial geostationary satellite, were recorded from a height of about 27 meters above sea surface. Sea Surface Height (SSH) was determined from the differences in electromagnetic path delay between the reflected and direct signal, found by cross-correlating the two signals and computing the lag of the peak. These retrievals were compared with the mean sea level reported from a tide gauge located at Platform Harvest.
A preliminary analysis showed a SSH precision of 5.6 cm, when using 0.5 seconds of data with a 4 ms coherent integration. An error analysis, based on the integration time of the cross-correlation, signal-to-noise ratio of the received signal, and the signal bandwidth predicted a theoretical error of 6.1 cm, RMSE , very close to that observed in the data.
Findings from this experiment demonstrate the feasibility of processing the full broadcast spectrum, composed of multiple independent data channels, as a single wide-band (400 MHz) signal and validate an error model that could be used in satellite mission studies.