Channel Calibration Method for ISAR Imaging System

In practical bistatic inverse synthetic aperture radar (ISAR) imaging systems, the echo signals are modulated by non-ideal amplitude and phase characteristics of the transmitting and receiving channels, which seriously distorts image quality. However, the conventional channel calibration method based on a transponder is not applicable to bistatic ISAR imaging systems, since the baseline of the system is up to hundreds of kilometers. A channel calibration method only using calibration satellite echo information is proposed for the system, with a linear frequency modulation (LFM) waveform. Firstly, echoes of the calibration satellite are collected by tracking the satellite and multi-period echoes are aligned in the time domain, according to the pulse compression result. Then, the signal to noise ratio (SNR) is improved by accumulating multi-period echoes coherently in the time domain and the calibration coefficient is constructed based on the accumulated signal. Finally, spectrum of the echo signal is multiplied with the calibration coefficient to compensate the influence of channel characteristics. The effectiveness of the proposed method is verified by the simulation experiment with real satellite echoes.

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HYBRID ONLINE MOBILE LASER SCANNER CALIBRATION THROUGH IMAGE ALIGNMENT BY MUTUAL INFORMATION

ISPRS Annals of Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsannals-iii-1-25-2016 ◽

2016 ◽

Vol III-1 ◽

pp. 25-31 ◽

Cited By ~ 2

Author(s):

Mourad Miled ◽

Bahman Soheilian ◽

Emmanuel Habets ◽

Bruno Vallet

Keyword(s):

Mutual Information ◽

Imaging System ◽

Laser Scanner ◽

Point Clouds ◽

Calibration Method ◽

Online Calibration ◽

Calibration Methods ◽

Laser Calibration ◽

Scanner Calibration

This paper proposes an hybrid online calibration method for a laser scanner mounted on a mobile platform also equipped with an imaging system. The method relies on finding the calibration parameters that best align the acquired points cloud to the images. The quality of this intermodal alignment is measured by Mutual information between image luminance and points reflectance. The main advantage and motivation is ensuring pixel accurate alignment of images and point clouds acquired simultaneously, but it is also much more flexible than traditional laser calibration methods.

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Calibration Method of Micro-polarizer Array Long-wave Infrared Imaging System

ACTA PHOTONICA SINICA ◽

10.3788/gzxb20194806.0611004 ◽

2019 ◽

Vol 48 (6) ◽

pp. 611004

Author(s):

闫羽 YAN Yu ◽

徐小红 XU Xiao-hong ◽

范之国 FAN Zhi-guo ◽

张强 ZHANG Qiang ◽

金海红 JIN Hai-hong

Keyword(s):

Infrared Imaging ◽

Imaging System ◽

Calibration Method ◽

Infrared Imaging System ◽

Long Wave ◽

Long Wave Infrared

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A Parasitic Array Receiver for ISAR Imaging of Ship Targets Using a Coastal Radar

International Journal of Antennas and Propagation ◽

10.1155/2016/8485305 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Fabrizio Santi ◽

Debora Pastina

Keyword(s):

Ad Hoc ◽

Imaging System ◽

Range Resolution ◽

Bounded Number ◽

Detection And Identification ◽

Isar Imaging ◽

Illegal Activities ◽

Simulated Analysis ◽

Parasitic Array ◽

Array Receiver

The detection and identification of ship targets navigating in coastal areas are essential in order to prevent maritime accidents and to take countermeasures against illegal activities. Usually, coastal radar systems are employed for the detection of vessels, whereas noncooperative ship targets as well as ships not equipped with AIS transponders can be identified by means of dedicated active radar imaging system by means of ISAR processing. In this work, we define a parasitic array receiver for ISAR imaging purposes based on the signal transmitted by an opportunistic coastal radar over its successive scans. In order to obtain the proper cross-range resolution, the physical aperture provided by the array is combined with the synthetic aperture provided by the target motion. By properly designing the array of passive devices, the system is able to correctly observe the signal reflected from the ships over successive scans of the coastal radar. Specifically, the upper bounded interelement spacing provides a correct angular sampling accordingly to the Nyquist theorem and the lower bounded number of elements of the array ensures the continuity of the observation during multiple scans. Anad hocfocusing technique has been then proposed to provide the ISAR images of the ships. Simulated analysis proved the effectiveness of the proposed system to provide top-view images of ship targets suitable for ATR procedures.

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