Michail Antoniou

Results of a Space-Surface Bistatic SAR Image Formation Algorithm

This paper reports progress in the development of an image formation algorithm suitable for stripmap space-surface bistatic synthetic aperture radar. A description of the proposed algorithm, which is a modification of the standard range-Doppler algorithm, is provided for the case when the transmitter and the receiver have parallel flight paths and unequal velocities. Both simulation and initial experimental results are presented to verify our analysis.

Space-Surface Bistatic SAR Image Formation Algorithms

This paper presents algorithms designed for a subclass of bistatic synthetic aperture radar (BSAR) called space-surface BSAR (SS-BSAR). Two SS-BSAR configurations are considered. The first one assumes a stationary, spaceborne transmitter and a moving airborne receiver. The second case is the generalized SS-BSAR configuration, where the transmitter is nonstationary. The transmitter and receiver have essentially different flight paths and velocities. For each configuration under investigation, the characteristics of the corresponding SS-BSAR received signal are examined first. Then, each proposed algorithm is derived analytically, and verified via simulation.

Experimental Demonstration of Passive BSAR Imaging Using Navigation Satellites and a Fixed Receiver

This letter demonstrates the feasibility of space-surface bistatic synthetic aperture radar using navigation satellites as transmitters of opportunity and a fixed ground-based receiver. Experiments with real satellite signals are described, and the obtained imagery is presented and discussed.

Quasi-optimal signal processing in ground Forward Scattering Radar

A signal processing algorithm for ground target detection using forward scattering radar (FSR) is presented in this paper. The effectiveness of the algorithm is shown using both simulated and experimental data. The algorithm is based on the matched filtering approach, where the correlation between the received signal and a set of pre-defined reference functions is calculated. The maximum of the correlation function indicates the estimated target parameters. The algorithm compresses the target signal, increasing signal-to-noise ratio, and allows identification of target speed and its position relative to the FSR geometry.

GNSS-based bistatic SAR: a signal processing view

This article presents signal processing algorithms used as a new remote sensing tool, that is passive bistatic SAR with navigation satellites (e.g. GPS, GLONASS or Galileo) as transmitters of opportunity. Signal synchronisation and image formation algorithms are described for two system variants: one where the receiver is moving and one where it is fixed on the ground. The applicability and functionality of the algorithms described is demonstrated through experimental imagery that ultimately confirms the feasibility of the overall technology.

Point Spread Function Analysis for GNSS-Based Multistatic SAR

This letter presents an analysis of the multistatic point-spread function (MPSF) for passive synthetic aperture radar (SAR) with navigation satellites as opportunity transmitters and a stationary receiver. It is shown that a noncoherent combination of bistatic SAR images, obtained by multiple, spatially separated satellites, can yield multistatic imagery that may be essentially improved in terms of resolution when compared with a single bistatic SAR image. The MPSF is derived analytically, for an arbitrary number of bistatic acquisitions and for any bistatic topologies. Analytical results are confirmed using both simulated and experimental data. The obtained result could be applied for the analysis of spatial resolution in multistatic real time radar, thus enabling the adaptive selection of the more suitable opportunity transmitters.

Optimal Signal Processing in Ground-Based Forward Scatter Micro Radars

The received signal in forward scatter radar (FSR) depends on the targets electrical size and trajectory, which are unknown a priori. As a result, in practical situations, it is impossible to obtain the accurate reference function at the reception side, and adaptation of optimal filtering is therefore proposed for this case. This paper presents a signal processing algorithm for ground target detection using FSR, which includes the construction of the adaptive reference functions and the identification of target velocity and its observation time. Furthermore, the algorithm performance is analytically determined under practical motion trajectories such as different motion directions and baseline crossing points, which indicate the effectiveness of the proposed algorithm in a practical case for FSR. The effectiveness of the algorithm is shown using both simulated and experimental data. Finally, the resolution in convoy targets in ground-based FSR is analytically obtained for the first time; the resolution is totally different from the resolution in conventional radar theory because of the target signature characteristics in ground-based FSR. The majority of the analytical results are verified experimentally.

Coherent Change Detection Using Passive GNSS-Based BSAR: Experimental Proof of Concept

This paper presents proof-of-concept methods and results on a passive synthetic aperture radar for surface change monitoring. The bistatic topology comprises navigation satellites (such as Global Positioning System, GLObal Navigation Satellite System (GLONASS), Galileo, or Beidou) as transmitters of opportunity and a fixed receiver on the ground. Surface monitoring is to be provided through coherent change detection. An experimental test bed built to confirm the concept of the system is described, and the appropriate experimental program is presented. Preliminary signal processing algorithms for change detection are derived. Experimentally measured changes are compared to the theoretical predictions, and the obtained results are discussed.

Passive GNSS-Based SAR Resolution Improvement Using Joint Galileo E5 Signals

This letter demonstrates the feasibility of improving range resolution in passive synthetic aperture radar with the Galileo navigation satellites as transmitters of opportunity. This can be done by an appropriate coherent combination of the Galileo E5a and E5b signals. The proposed approach is analytically derived and is confirmed both by simulation and experiments.

Point Spread Function Analysis for BSAR With GNSS Transmitters and Long Dwell Times: Theory and Experimental Confirmation

This letter conducts a point spread function (PSF) analysis for bistatic synthetic aperture radar (BSAR) systems where the transmitter is in medium Earth orbit, and the receiver is fixed on the ground. To achieve a reasonable azimuth resolution under such a configuration, the trajectory of the satellite can no longer be approximated as a straight line; therefore, current methods for PSF analysis are insufficient. The solution proposed involves extension of the generalized ambiguity function to accommodate satellite trajectory curvature. The theoretical analysis shows effects unlike those observed in monostatic or even the general BSAR and is verified by both simulation and experimental results using navigation satellites as the transmitting platforms.