Evaluation Test of GPS Local Area Remote Sensing System

摘要

In this paper a GPS local area remote sensing system isproposed to measure ocean wave characteristics, such aswavelength and wave period which can be utilized toimprove security of mooring and navigation in harbor.The remote sensing system receives GPS signals fromline-of-sight channel and fading multipath channelreflected from specified sea-surface with two sub-systemsrespectively and then identify their arrival times andconvert them to wave information according to status ofGPS satellite and remote sensing system. One sub-systemhas a conventional antenna and front-end to receive lineof-sight signal in which real-time azimuth and elevationof visible satellite are obtained. The other sub-systemincludes left hand circular polarization arrayed antennaand wide bandwidth front-end to receive reflected signalsfrom sea-surface. Especially the directional pattern of thearrayed antenna is shaped into a very narrow fan beam toreceive reflected signals from narrow span, and thefollowing front-end has enough bandwidth to identifyeach reflected signal. Software GPS receiver has alsobeen developed to monitor signal variation, process massavailable signals acquired from two sub-systemssimultaneously. Teager-Kaiser Energy Operator is alsoapplied on the correlator output in software GPS receiverto identify arrival time of each reflected signal. In order toverify that the remote sensing system can measure oceanwave characteristics, a numerical simulation test and anexperimental test were carried out. In the numericalsimulation, sea swell which is considered as one of majordestructive factors near a harbor area is targeted andwavelength and wave period of sea swell can be definitelymeasured with different intensities and arrival times ofreflected signals. In experimental test, the constructedremote sensing system was able to receive and identifyreflected signals. Arrival times of line-of-sight signal andsome reflected signals were also obtained.