Tomographic Performance of Multi-Static Radar Formations: Theory and Simulations

Abstract

3D imaging of Earth’s surface layers (such as canopy, sub-surface, or ice) requires not just the penetration of radar signal into the medium, but also the ability to discriminate multiple scatterers within a slant-range and azimuth resolution cell. The latter requires having multiple radar channels distributed in across-track direction. Here, we describe the theory of multi-static radar tomography with emphasis on resolution, SNR, sidelobes, and nearest ambiguity location vs. platform distribution, observation geometry, and different multi-static modes. Signal-based 1D and 2D simulations are developed and results for various observation geometries, target distributions, acquisition modes, and radar parameters are shown and compared with the theory. Pros and cons of multi-static modes are compared and discussed. Results for various platform formations are shown, revealing that unequal spacing is useful to suppress ambiguities at the cost of increased multiplicative noise. In particular, we demonstrate that the multiple-input multiple-output (MIMO) mode, in combination with nonlinear spacing, outperforms the other modes in terms of ambiguity, sidelobe levels, and noise suppression. These findings are key to guiding the design of tomographic SAR formations for accurate surface topography and vegetation mapping.

New Approach of Deployment of the Multi-static Radars Based on an Aperture Angle and the Probability of False Alarm

“…It should be noted that ambiguous copies of targets outside the scene of interest might nonetheless fall within the scene of interest, even if the scene of interest is smaller than the position of the nearest ambiguity. The closest ambiguity for a flat surface, according to Seker and Lavalle [17], is at:…”

“…The performance can also be analyzed according to technologies which are characteristic of the nature of the used signals for the transmitters [15]. Thus, criteria such as resolution can be used to determine the ability of a radar to identify several distinct targets [16] and the location of the nearest ambiguity can be used to determine how far away the radar can detect the next ambiguity or replica [17]. In addition to these parameters, we also have the probability of detection which is the possibility that a radar receives the echo of a target compared to the noise [18,19].…”

“…In addition to these parameters, we also have the probability of detection which is the possibility that a radar receives the echo of a target compared to the noise [18,19]. All the multi-static radar systems have parameters of deployment such as spacing between the sensors, the physical angle of slope, the slope compared to the base line, and the number of sensor's radars for the formation of the array [17]. Multi-static radars is primarily formed of phased antenna arrays [20][21][22][23] and spacing between them is estimated in wavelength [24].…”

Mission Design and Orbit-Attitude Control Algorithms Development of Multistatic SAR Satellites for Very-High-Resolution Stripmap Imaging

“…Lopez-Dekker et al [1] introduced a multistatic SAR concept that can overcome the limitations of monostatic SAR systems for azimuth resolution. Recently, various multistatic SAR missions performed by two or more SAR satellites have been actively investigated because they can increase the dimension of the measurement space or improve the signalto-noise ratio [1,2,5,16,17]. The multistatic SAR system using a cross-track formation can produce accurate tomography, a three-dimensional (3D) map, and a digital elevation model (DEM) through single-pass interferometry [1,16].…”

Experimental evaluation of the performances of multi-sensors ultrasonic deployment geometries

“…For large-scale deployments such as SAR satellite systems, better performance is achieved when the spacing is expressed as a function of the pulse repetition rate to improve resolution [40] and ambiguity. Despite this, large-scale deployment systems have problems with radar fidelity over the study area [41].…”