Simulation-Based Feasibility Analysis of Ship Detection Using GNSS-R Delay-Doppler Maps

Abstract

In this article, we carry out a simulation analysis of ship detection via Global Navigation Satellite System-Reflectometry (GNSS-R) delay-Doppler map (DDM). The GNSS-R DDM simulator used here is a modified version of an algorithm conceived for the generation of GNSS-R DDMs of the sea surface. The new algorithm is based on an analytical model for the radar cross section of ships and is able to properly account for the presence of ship targets within the scene. The proposed GNSS-R DDM simulator is, then, exploited for assessing the viability of GNSS-R in ship detection applications at low incidence angles, where the adopted scattering models provide accurate results. The aim of the implemented simulation setup is to analyze what are the preferable conditions for ship detection using standard GNSS-R signal processing chain receiver and compare typical forward left-hand circularly polarized GNSS-R systems with nonstandard backward right-hand circularly polarized (RHCP) GNSS-R. The simulation study is two fold: first, detection performance is evaluated at spaceborne and airborne altitudes for both polarization channels under favorable detection conditions. Then, visibility of ship targets is assessed in terms of their location within the DDM. Simulation results show that ship detection is problematic when using satellite data, whereas interesting results are achieved at airborne altitudes, provided that the aircraft is approximately between the GNSS satellite and the target, and that appropriate RHCP polarization is probed. In such configurations, signal-to-noise-ratios larger than 10 dB are obtained with airborne receivers collecting the RHCP signal.

The IEEE-SA Working Group on Spaceborne GNSS-R: Scene Study

“…It was based on a sea clutter compensation step, using an adaptive threshold to consider spatial variability in the sea background and/or noise statistics. More recently, a few more works [111,112] have provided new insights. In [111], a matched filter was proposed using data from the UK-TDS-1 to detect seatargets in a DDM sequence without requirements for any (pre)detection.…”

“…In [111], a matched filter was proposed using data from the UK-TDS-1 to detect seatargets in a DDM sequence without requirements for any (pre)detection. Finally, simulations for ship detection applications at low incidence angle were performed in [112] using a stochastic simulator for sea surfaces.…”

Maritime Multiple Moving Target Detection Using Multiple-BDS-Based Radar: Doppler Phase Compensation and Resolution Improvement

“…(e) (f) Figures [12][13][14][15][16] show the one-dimensional range image Doppler compensation results, one-dimensional range image target peak identification results, range inverse results, and DDM results of three ship targets in simulation 2, which verify that multiple fetched ship targets can be detected with better strength using the MDTC method with noise and sea clutter backgrounds in a 10 s accumulation, and the ship RCS distribution structure can be further acquired by the proposed target peak identification method and range inversion method. In the other situation, since we have estimated the target information, we can acquire rough target distance ranges and reverse them using the range inverse method 2.…”

“…Reference [13] notes that for large and medium-sized targets on the sea surface, GNSS-R detection can acquire a sufficient signal-to-noise ratio (SNR) of 20~25 dB [14] after several seconds of accumulation. Next, one study in the literature [14,15] simulated a delay-Doppler map (DDM) of large-scale targets and verified the effectiveness of large-scale target detection based on short time accumulation signals using the range-Doppler Fourier method. In terms of theoretical construction and system model, reference [16] gives an extremum approximation algorithm for advanced receiver autonomous integrity monitoring, and triple-frequency combining observation models have been studied for precise point positioning [17].…”

“…The incoherent range walk compensation method was proposed for spaceborne GNSS-R imaging [3], and GNSS-R-based moving target indication is studied in the literature [21]. In terms of marine target detection, ocean surface target detection and positioning were discussed [22], the delay and Doppler tracking errors were analyzed [15], and the feasibility analysis of ship detection by DDM was simulated [23]. In order to distinguish sea targets from sea clutter, the blind sea clutter suppression method was discussed [24].…”