Altimetry using Ku-band signals of opportunity

Rashmi Shah (Jet Propulsion Laboratory, United States)


Bruce Haines (Jet Propulsion Laboratory, United States); James Garrison (Purdue University, United States)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: Regional and Global CAL/VAL for Assembling a Climate Data Record

Presentation type: Type Poster

Remote sensing of ocean surface using signals of opportunity has been done using Global Navigation Satellite Signals (GNSS) for last two decades. Recently, techniques that have been developed for GNSS have been expanded to other signals of opportunity (SoOp) like digital communication signals. The work presented here shows results of experiment, which used a Ku-band signal to measure sea surface height (SSH).

A reflectometry experiment was conducted at Platform Harvest (Jason-2 calibration and validation site), where a commercial satellite TV signal located at Ku-band (DirecTV) was recorded from a height of about 27 meters above sea surface. The height 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. It was then compared with the mean sea level value from the tide gauge located at Platform Harvest. The correlation between the two measurements was found to be high with correlation coefficient of 0.9.

The precision of the estimation of height was found to be 13 cm from using 55 seconds of data. A theoretical error analysis was performed to compute the instrumental expected error based on the integration time of the cross-correlation, signal-to-noise ratio of the received signal, and data rate of the transmitting signal; and it was found the experimental error matched theoretical expected error, which was also found to be 13 cm.
Rashmi Shah
Jet Propulsion Laboratory
United States