The Doppler Characteristics of Sea Echoes Acquired by Motion Radar

• Published in: Remote sensing (Basel, Switzerland) Vol. 15; no. 19; p. 4888
• Main Authors: Du, Pengbo, Wang, Yunhua, Li, Xin, Cui, Jianbo, Zhang, Yanmin, Li, Qian, Zhang, Yushi
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-10-2023
• Subjects: Bandwidths; Doppler effect; Doppler shift; Echoes; Hypotheses; Mathematical models; Microwave radar; Microwave scattering; motion platform; Numerical methods; Offshore platforms; Radar; Radar beams; radar echoes; Radar systems; sea surface; Simulation; Spectrum allocation; spectrum bandwidth; Target detection; Thermal noise; Time series
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs15194888

The Doppler characteristics of sea surface echoes reflect the time-varying characteristics of the sea surface and can be used to retrieve ocean dynamic parameters and detect targets. On airborne, spaceborne and shipborne radar platforms, radar moves along with the platforms while illuminating the sea surface. In this case, the area of the sea surface illuminated by radar beam changes rapidly with the motion, and the coherence of the backscattered echoes at different times decreases significantly. Therefore, the Doppler characteristics of the echoes would also be affected by the radar motion. At present, the computational requirements needed to simulate the Doppler spectrum of the microwave scattering field from the sea surface based on numerical methods are huge. To overcome this problem, a new method based on the sub-scattering surface elements has been proposed to simulate the Doppler spectrum of sea echoes acquired by a moving microwave radar. A comparison with the results evaluated by the SSA demonstrate the availability and superiority of the new method proposed by us. The influences induced by radar motion, radar beamwidth, incident angle, and thermal noise on the Doppler characteristics are all considered in this new method. The simulated results demonstrate that the spectrum bandwidth of sea surface echoes acquired by radar on the dive staring motion platform becomes somewhat narrower.