Abstract
In this paper, we present a novel signal processing method for video synthetic aperture radar (ViSAR) systems, which are suitable for operation in unmanned aerial vehicle (UAV) environments. The technique improves aspects of the system’s performance, such as the frame rate and image size of the synthetic aperture radar (SAR) video. The new ViSAR system is based on a frequency-modulated continuous wave (FMCW) SAR structure that is combined with multiple-input multiple-output (MIMO) technology, and multi-channel azimuth processing techniques. FMCW technology is advantageous for use in low cost, small size, and lightweight systems, like small UAVs. MIMO technology is utilized for increasing the equivalent number of receiving channels in the azimuthal direction, and reducing aperture size. This effective increase is achieved using a co-array concept by means of beat frequency division (BFD) FMCW. A multi-channel azimuth processing technique is used for improving the frame rate and image size of SAR video, by suppressing the azimuth ambiguities in the receiving channels. This paper also provides analyses of the frame rate and image size of SAR video of ViSAR systems. The performance of the proposed system is evaluated using an exemplary system. The results of analyses are presented, and their validity is verified using numerical simulations.
Highlights
Synthetic aperture radar (SAR) technology is an active microwave remote sensing technique, capable of day/night, all-weather operation, used to detect and acquire electromagnetic information about objects without physical contact [1,2,3]
We design an exemplary multiple-input multiple-output (MIMO) video SAR system based on beat frequency division (BFD) frequency-modulated continuous wave (FMCW)
The performance of the proposed system is evaluated in terms of peak sidelobe ratio (PSLR), resolution, image size, and frame rate, using numerical simulations
Summary
Synthetic aperture radar (SAR) technology is an active microwave remote sensing technique, capable of day/night, all-weather operation, used to detect and acquire electromagnetic information about objects without physical contact [1,2,3]. MIMO and multi-channel azimuth processing techniques to video synthetic aperture radar (ViSAR), improvements to the frame rate and image size of SAR video can be achieved, without compromising other aspects of the system’s performance. MIMO technology can be combined with ViSAR systems using orthogonal waveforms for FMCW radars such as the beat frequency division (BFD) waveform [28], the chirp rate division waveform [28], and the OFDM (or interleaved OFDM, I-OFDM) chirp waveform [29] This MIMO technology can be used for various objectives, for example, the virtual array can be used to increase the equivalent number of phase centers or receiving channels, for the reduction of the aperture size. We derive a signal model based on the MIMO radar signal model, and propose a novel signal processing method for ViSAR systems suitable for UAV environment operation, which improves aspects of the system performance, such as frame rate, and image size of the SAR video.
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