Comparison and analysis of point target reference spectrum of FMCW synthetic aperture imaging sensor

Yue Liu,Yunkai Deng ,Robert Wang,Xiaoxue Jia ,Xiaotao Han

doi:10.1186/1687-6180-2012-210

Abstract

Abstract Frequency-modulated continuous-wave (FMCW) synthetic aperture imaging sensor (SAIS) combines FMCW technology and SAIS techniques which makes a lightweight, high-resolution, and cost-effective imaging sensor. FMCW SAIS systems are going to play an important role in airborne and spaceborne earth observation fields. However, the stop-and-go approximation used in conventional pulsed SAIR (e.g., synthetic aperture radar—SAR) is no longer valid due to the long signal duration time or low wave propagation speed. To exploit the potentialities of an accurate signal model under FMCW SAIS circumstances, this article presents the relationship and remarkable differences between the analytical FMCW SAIS point target reference spectrum model and the traditional ones in pulsed SAR and Synthetic Aperture Acoustic imaging system, and validates the significance of the additional range–azimuth coupling term and range walk term in FMCW SAIS spectrum introduced by the variation of slant range during the long pulse durations, and highlight the limitations of other two spectra. Finally, the simulation experiments are carried out to compare the performance of the aforementioned spectrum formulations.

Highlights

Frequency-modulated continuous-wave (FMCW) synthetic aperture imaging sensor (SAIS) combines FMCW technology and SAIS techniques which makes a lightweight, high-resolution, and cost-effective imaging sensor [1]
We concentrate on the differences and relationship between the analytical FMCW SAIS point target reference spectrum (PTRS) model and the traditional ones, and validate the significance of the differences, in order to present a principle of choosing proper signal models in different configurations
Comparing these results shows that the focusing performance of synthetic aperture acoustic (SAA) filtering function is much better than that of the conventional synthetic aperture radar (SAR), but still worse than the accurate FMCW SAIS

Summary

Introduction

Frequency-modulated continuous-wave (FMCW) synthetic aperture imaging sensor (SAIS) combines FMCW technology and SAIS techniques which makes a lightweight, high-resolution, and cost-effective imaging sensor [1]. By representing the accurate instantaneous slant range during the pulse duration time on the transmitted and received signal [2], the authors developed an analytical signal model for the FMCW SAR imaging system. We will highlight the significance of the range–azimuth coupling term and range walk term introduced by the variation of the slant range during the long pulse duration, by showing the different simulation results based on the different PTRS models.

Results

Conclusion