A Refined Two-Dimensional Nonlinear Chirp Scaling Algorithm for Geosynchronous Earth Orbit Sar

Zeng, Tao; Yang, Wu; Ding, Zegang; Liu, Dacheng; Li, Teng

doi:10.2528/pier13071206

Cited by 13 publications

(5 citation statements)

References 23 publications

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“…As a result, slow time is changed from the flight direction to the new direction denoted by the red dotted line. As such, the deviation between the red dotted line and the flight trajectory complies with Equation (13). The operation makes the new slow time and fast time directions orthogonal, and changes the squint mode to an equivalent broadside mode.…”

Section: Adjusting the Starting Time Of The Receive Windowmentioning

confidence: 85%

“…Hu et al [12] improved the conventional nonlinear CS algorithm by accounting for a linear spatial variance in the range direction in the polynomial model. Tao et al [13] developed the nonlinear azimuth CS algorithm by introducing spatially variant components in the classic hyperbolic model. Sun et al [14] considered spatial variation in both the range and azimuth directions in a fifth-order polynomial model, and a 5-m resolution within an 82 × 95 km swath was achieved using range cell migration (RCM) equalization and sub-band synthesis technologies.…”

Section: Slant Range History Of Squint Mode Geo Sarmentioning

confidence: 99%

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Squint Mode GEO SAR Imaging Using Bulk Range Walk Correction on Received Signals

Geng

et al. 2018

Remote Sensing

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Geosynchronous synthetic aperture radar (GEO SAR) has the potential for conducting long-term observation of target zones, which is essential for remote sensing applications such as disaster monitoring and vegetation measurements. The squint imaging mode is crucial for long-term observation using GEO SAR. However, this type of SAR imaging is problematic because the squint mode introduces a nonzero range cell walk, which increases the prevalence of invalid data in echoes and intensifies the coupling between the azimuth and range. Therefore, this paper proposes a novel squint mode GEO SAR imaging method based on the correction of the bulk range walk of received signals. Adjusting the starting time of the receiving window significantly reduces the redundancy in echoes. Then, first-order filtering, range cell migration correction, range compression, partial dechirp, and azimuth compression are used to obtain the imaging result. Simulation results for the GEO SAR imaging of Wenchuan County in China demonstrate that the proposed algorithm can achieve a resolution of 5 m within a 30 × 30 km swath over 48% of the orbital period.

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Section: Adjusting the Starting Time Of The Receive Windowmentioning

confidence: 85%

Section: Slant Range History Of Squint Mode Geo Sarmentioning

confidence: 99%

Squint Mode GEO SAR Imaging Using Bulk Range Walk Correction on Received Signals

Geng

et al. 2018

Remote Sensing

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“…Due to its advantages GEO SAR can be well applied in topographic mapping water resource monitoring and soil moisture determination, etc. [1,4]. For example, a GEO SAR system called Geosynchronous Earth Monitoring by Interferometry and Imaging (GEMINI) was put forward in 2012 to acquire Earth surface data [5,6].…”

Section: Introductionmentioning

confidence: 99%

Analysis and Compensation of Ionospheric Time-Variant Tec Effect on Geo Sar Focusing

Liang¹,

Li²

2019

PIER M

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Compared to low Earth orbit (LEO) synthetic aperture radar (SAR), geosynchronous (GEO) SAR has a larger coverage and shorter revisit period. However, due to its longer integration time it will be affected by ionospheric time-variant total electron content (TEC), which introduces a phase error into the SAR azimuth signal. Using U.S. total electron content (USTEC) data, TEC variation with time on GEO SAR track is analyzed. It is shown that quadratic phase error caused by time-variant TEC is main effect on image focusing compared to higher order errors. Therefore, contrast optimization autofocus (COA) algorithm can be used for compensation. The key steps of COA are given. Simulations based on scenes derived from PALSAR2 data demonstrate the effectiveness of COA.

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“…Chirp signals have been widely used in radar systems [ 13 , 14 , 15 ]. Owing to their properties of high compression gain, good resistance to narrowband interferences and multipath effects [ 12 , 14 ], chirp signals have also been used extensively in other fields, such as measurement [ 16 ], ultra-wide band communication [ 17 ] and optical fiber communication [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

A Low-Ambiguity Signal Waveform for Pseudolite Positioning Systems Based on Chirp

Liu

Huang

Kou

et al. 2018

Sensors

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Signal modulation is an essential design factor of a positioning system, which directly impacts the system’s potential performance. Chirp compressions have been widely applied in the fields of communication, radar, and indoor positioning owing to their high compression gain and good resistance to narrowband interferences and multipath fading. Based on linear chirp, we present a modulation method named chirped pseudo-noise (ChPN). The mathematical model of the ChPN signal is provided with its auto-correlation function (ACF) and the power spectrum density (PSD) derived. The ChPN with orthogonal chirps is also discussed, which has better resistance to near-far effect. Then the generation and detection methods as well as the performances of ChPN are discussed by theoretical analysis and simulation. The results show that, for ChPN signals with the same main-lobe bandwidth (MLB), generally, the signal with a larger sweep bandwidth has better tracking precision and multipath resistance. ChPN yields slighter ACF peaks ambiguity due to its lower ACF side-peaks, although its tracking precision is a little worse than that of a binary offset carrier (BOC) with the same MLB. Moreover, ChPN provides better overall anti-multipath performance than BOC. For the ChPN signals with the same code rate, a signal with a larger sweep bandwidth has better performance in most aspects. In engineering practice, a ChPN receiver can be implemented by minor modifications of a BOC receiver. Thus, ChPN modulation shows promise for future positioning applications.

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A Refined Two-Dimensional Nonlinear Chirp Scaling Algorithm for Geosynchronous Earth Orbit Sar

Cited by 13 publications

References 23 publications

Squint Mode GEO SAR Imaging Using Bulk Range Walk Correction on Received Signals

Squint Mode GEO SAR Imaging Using Bulk Range Walk Correction on Received Signals

Analysis and Compensation of Ionospheric Time-Variant Tec Effect on Geo Sar Focusing

A Low-Ambiguity Signal Waveform for Pseudolite Positioning Systems Based on Chirp

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