WIDEBAND OCEAN ALTIMETRY USING KU AND K-BAND SATELLITE SIGNALS OF OPPORTUNITY (SoOP)
thesisposted on 30.04.2021, 18:46 by Soon Chye Ho
This dissertation applies an ocean remote sensing method using Signals of Opportunity (SoOp), specifically reflected digital telecommunication satellite signals. The fundamental observation is the cross correlation waveform from the direct and reflected signal. Relationships are derived between the coherence time of the waveform and SSH of the sea surface. A proof-of-concept experiment has demonstrated that wideband (400 MHz) signals of opportunity (SoOp) transmitted in K and Ku-band from geostationary satellites can be used for coastal altimetry. An important finding from this experiment is that the full broadcast spectrum consisting of multiple digital channels can be processed as a single wideband signal source. An established error model for Global Navigation Satellite System interferometric altimetry (iGNSS-R) was shown to accurately represent the sea surface height (SSH) retrievals when evaluated using the full bandwidth. This experiment was conducted over a 72 hour period at Platform Harvest off the Pacific Coast. Co-located tide gauge and LiDAR measurements were used as in situ data. Two anomalies were observed in the experiment: 1. Multiple peaks in the cross correlation waveform from one polarization of Ku-band frequency. 2. Decrease in SNR from loss of a data channel. When the instances of multiple peaks were eliminated and the equivalent bandwidth recomputed using only the active channels, SSH error from these cases agreed well with the model prediction. Application of SoOp wideband altimetry will therefore require a monitoring capability to identify changes in the transmission spectrum, total power, and waveform shape, for quality control and setting an appropriate observation error covariance.The measurement precision from a satellite receiver is predicted to be between 4-6 cm using the error model.