A Spectrum Correction Algorithm Based on Beat Signal of FMCW Laser Ranging System

Hao, Yi; Song, Ping; Wang, Xuanquan; Zhang, Pan

doi:10.3390/s21155057

Cited by 6 publications

(2 citation statements)

References 34 publications

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“…However, these methods are difficult to realize and take up a lot of resources. In addition, based on discrete wavelet packet transformation [ 21 ], all-phase [ 22 ], decomposition filtering-based dual-window correction algorithms [ 23 ], autocorrelation [ 24 ], and neural network methods [ 25 ], the frequency estimation can be realized. The influence of white noise on frequency estimation has also been analyzed [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Beat-Notes Acquisition of Laser Heterodyne Interference Signal for Space Gravitational Wave Detection

Wang

Sui

et al. 2023

Sensors

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In space gravitational wave detection missions, the laser heterodyne interference signal (LHI signal) has a high-dynamic characteristic due to the Doppler shift. Therefore, the three beat-notes frequencies of the LHI signal are changeable and unknown. This may further lead to the unlocking of the digital phase-locked loop (DPLL). Traditionally, fast Fourier transform (FFT) has been used as a method for frequency estimation. However, the estimation accuracy cannot meet the requirement of space missions because of the limited spectrum resolution. In order to improve the multi-frequency estimation accuracy, a method based on center of gravity (COG) is proposed. The method improves the estimation accuracy by using the amplitude of the peak points and the neighboring points of the discrete spectrum. For different windows that may be used for signal sampling, a general expression for multi-frequency correction of the windowed signal is derived. Meanwhile, a method based on error integration to reduce the acquisition error is proposed, which solves the problem of acquisition accuracy degradation caused by communication codes. The experimental results show that the multi-frequency acquisition method is able to accurately acquire the three beat-notes of the LHI signal and meet the requirement of space missions.

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Section: Introductionmentioning

confidence: 99%

Beat-Notes Acquisition of Laser Heterodyne Interference Signal for Space Gravitational Wave Detection

Wang

Sui

et al. 2023

Sensors

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“…To date, a 100 kHz-level measuring rate has been realized with micrometer-scale resolution [8]. Reliable precision is guaranteed by more accurate system calibration [18] and more effective signal analysis algorithms [19,20]. Additionally, the use of silicon photonics chips and embedded digital signal processors makes compatible and real-time measurements possible [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Frequency-swept feedback interferometry for noncooperative-target ranging with a stand-off distance of several hundred meters

Wang

Dai

et al. 2022

PhotoniX

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Frequency-swept interferometry (FSI) is a powerful ranging method with high precision and immunity to ambient light. However, the stand-off distance of the current FSI-based ranging system for noncooperative targets is relatively short because the weak echo power cannot provide the needed signal-to-noise ratio (SNR). Here, we report a ranging method that combines FSI and the laser feedback technique. Compared with conventional FSI, the interference between the weak echo signal and the local oscillator occurs in the laser cavity, which enhances the signal spontaneously and then provides an improved SNR. In the experiments, the detection limit of the echo power is less than 0.1 fW, with a 1 mW probe beam. Based on the enhancement from the laser feedback technique, the system can detect a noncooperative target that is up to hundreds of meters away in space without extra optical amplifiers. On the other hand, a large stand-off distance makes the system sensitive to environmental disturbance, which degrades the ranging precision. To address this issue, an interferometry-based compensation device, which is also sensitive to weak echoes from noncooperative targets, is proposed to monitor the optical-path-length drifts and ensure accurate beat frequency recognition. Moreover, the device can record distance changes during the integration time of ranging and track a moving target precisely with improved temporal resolution. Owing to the high sensitivity and the validity of the compensation approach, the standard deviation in 10 measurements is better than 0.07 mm when targeting an aluminum sheet at approximately 152 m. Generally, with a large range, high relative precision, and low photon consumption, the novel technical scheme for laser ranging demonstrates new capabilities that promise to enable a wide range of applications, such as large equipment assembly and noncooperative-target tracking.

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A Study on the Structural Elements of the Educational Philosophy “Establishing Morality and Cultivating Students” in English Teaching in Middle School Based the Process of Moral Formation

Chen

Li²,

et al. 2023

SHS Web Conf.

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The purpose of this paper is to analyze the structural elements of the moral education when applying the educational philosophy “establishing morality and cultivating students” in English teaching in middle school in the process of the middle school students’ moral formation from the perspective of three analyses. The first is to interpret four levels of moral education from the moral awareness, the moral emotion and the moral will. The second is to interpret the moral behavior based on the moral levels. The third on the structural elements of applying “establishing morality and cultivating students” to English teaching in middle school is to interpret the division of setting the structural elements of the middle school students’ moral education in English teaching based on the first and the second analyses in combination with the middle school students’ characteristics of moral education.

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A Spectrum Correction Algorithm Based on Beat Signal of FMCW Laser Ranging System

Cited by 6 publications

References 34 publications

Beat-Notes Acquisition of Laser Heterodyne Interference Signal for Space Gravitational Wave Detection

Beat-Notes Acquisition of Laser Heterodyne Interference Signal for Space Gravitational Wave Detection

Frequency-swept feedback interferometry for noncooperative-target ranging with a stand-off distance of several hundred meters

A Study on the Structural Elements of the Educational Philosophy “Establishing Morality and Cultivating Students” in English Teaching in Middle School Based the Process of Moral Formation

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