Mission Requirements for a Dedicated Small-Satellite SAR System

Abstract

This thesis examines the suitability of a small-satellite Synthetic Aperture Radar (SAR) system for two applications that are relevant to the economic and ecological security of New Zealand, namely detecting ships in the New Zealand Exclusive Economic Zone (EEZ) and measuring tectonic deformations of New Zealand’s land surface. For both applications, the objective is to find the minimum SAR image quality in terms of resolution and noise level to yield useful results. ‘Small’ in this context is defined as a form factor between 6U and 12 U. The proposed SAR system is dedicated to the two targeted applications, i.e., the performance has to be sufficient for the aforementioned two SAR applications. The analyses for both applications were conducted using TerraSAR-X SAR data. For the ship detection application, the desired detection performance is defined as a probability of detection of 0.5 while maintaining a Probability of False Alarm below 10−10, which corresponds to two false alarms per whole coverage of the New Zealand EEZ. The proposed small-satellite SAR system requires a spatial resolution of 4m2 and a system Noise-Equivalent Sigma Zero (NESZ) of −1.7 dB to achieve this performance. For the second application, Persistent Scatterer Interferometry (PSI) is used to generate deformation maps of a Region-of-Interest (ROI) at varying levels of image quality. It was found that the deformation signal can be captured within an accuracy of 5mm with an NESZ of below 0 dB, and with a spatial resolution of 7.6m2. A preliminary system design is derived for both the proposed small-satellite SAR applications. It is shown that the system requirements derived from both applications are compatible, and a suitable system design is presented. This system is compatible with the objective of a small-satellite SAR system. For example, it is found that a transmit power of 15W is sufficient for the targeted applications. A key finding of this study is that, in principle, a small-satellite SAR system can be used to detect ships in the New Zealand EEZ and to measure surface deformations using PSI. The quality of the data produced by the system is sufficient to fulfil the application requirements derived for the New Zealand-specific use cases.