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phase coding IN ITERATIVE SYNTHESIS OF COMPUTER-GENERATED HOLOGRAMS

OPTICS AND LASER TECHNOLOGY 1995年第4期27卷 223-228页

作者： GOLUB, MA PAVELYEV, VS RUSSIAN ACAD SCI INST IMAGE PROC SYST 151 MOLODOGVARDEJSKAYA SAMARA 443001 RUSSIA

A new method is investigated for phase-only hologram synthesis. The method combines iterative calculation of the hologram phase function with the coding of the amplitude-phase characteristics of the complex transmission function into phase characteristics. The results of computational experiments are presented. The phase masks and reconstructed object images are also presented.

关键词： phase-ONLY HOLOGRAMS MATHEMATICAL HOLOGRAMS KIRK-JONES METHOD phase coding BESSEL FUNCTION

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Effects of phase coding on Doppler Spectra in PPAR Weather Radar

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2018年第4期56卷 2043-2065页

作者： Ivic, Igor R. Univ Oklahoma Cooperat Inst Mesoscale Meteorol Studies Norman OK 73072 USA NOAA OAR Natl Severe Storms Lab Norman OK 73072 USA

One option for the improvement of weather radar technology is the use of dual-polarized phased-array radar for weather observations. Several risk factors on this path have been identified and one of the most important ones is the existence of significant cross-polar patterns inherent to the phased-array antenna. These antenna patterns induce cross-coupling between returns from the two orthogonal radiation planes, which results in the biases of polarimetric variable estimates. Furthermore, the inductive and capacitive coupling in hardware behind the antenna may exacerbate the cross-coupling effects. This presents a formidable challenge because sufficient cross-polar isolation is difficult to achieve by the antenna hardware alone. Hence, additional approaches are required to reduce the biases due to cross-coupling. One proposed technique is a 180 degrees pulse-to-pulse phase change of signals injected in either the horizontal or vertical ports of the transmission elements. This approach was analyzed for signals processed in the time domain but its effects in the frequency domain have not been investigated. Herein, these effects are considered in the presence of nondepolarizing scatterers.

关键词： phase coding phased-array radar (PAR) radar polarimetry radar signal processing weather radar

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3-D Shape measurement based on the unequal-period combination approach of phase coding and sinusoidal fringe

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JOURNAL OF MODERN OPTICS 2019年第21期66卷 2083-2092页

作者： Fu, Ling Gao, Dingshan Huazhong Univ Sci & Technol Sch Elect Informat & Commun Wuhan Hubei Peoples R China Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan Hubei Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan Hubei Peoples R China

The phase coding plus sinusoidal fringe method involves embedding the codeword into the phase domain, and is suitable for different contrast variation surfaces. However, as the number of phase coding fringe cycles increase, the fringe order becomes difficult to judge, ultimately leading to phase unwrapping errors. To resolve this issue, an unequal-period combination approach of phase coding and sinusoidal fringe was proposed. The main idea of this method was to project N cycles phase coding fringe, 2N (3N, 4N ...) cycles sinusoidal fringe, and the phase coding fringe was ahead of the sinusoidal fringe. This method alleviated the difficulty in judging the fringe order and, consequently, improved measurement accuracy. Experiment results validated the efficiency and accuracy of this novel method.

关键词： 3-D shape measurement phase coding sinusoidal fringe unequal-period Fringe projection profilometry phase retrieval

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Detection and Mitigation of Second-Trip Echo in Polarimetric Weather Radar Employing Random phase coding

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2012年第4期50卷 1240-1253页

作者： Cao, Qing Zhang, Guifu Palmer, Robert D. Lei, Lei Univ Oklahoma Atmospher Radar Res Ctr Norman OK 73072 USA Univ Oklahoma Sch Meteorol Norman OK 73072 USA Univ Oklahoma Sch Elect & Comp Engn Norman OK 73072 USA

This study presents a new identification and mitigation scheme of second trip contamination for pulsed Doppler polarimetric weather radars with the ability of random phase coding. This scheme can be easily implemented in a magnetron radar without any hardware changes. For relatively weak contamination, identification and mitigation are based on a multilag processing method, which uses multiple lags of both the auto- and cross-correlation functions to estimate radar moments. For relatively strong contamination, instantaneous phase variations of horizontal and vertical polarization channels are combined into a simple fuzzy-logic scheme to complete the identification. Data from the C-band OU-PRIME radar are used to demonstrate the effectiveness of the proposed scheme for identification and mitigation of second-trip echoes.

关键词： phase coding polarimetric measurements weather radar

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A 3D shape measurement method based on novel segmented quantization phase coding

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OPTICS AND LASERS IN ENGINEERING 2019年 113卷 62-70页

作者： Wang, Lin Chen, Yuan Han, Xu Fu, Yanjun Zhong, Kejun Jiang, Guangyu Nanchang Hangkong Univ Educ Minist China Key Lab Nondestruct Testing Nanchang 330063 Jiangxi Peoples R China

Codeword is very important in phase unwrapping based on phase coding method. Each phase coding fringe is marked with a unique codeword and then used to determine the fringe order for absolute phase retrieval. However, the traditional phase coding method is limited by the number of codeword. To overcome this problem, a segmented quantization phase coding and decoding method is proposed to achieve absolute phase retrieval without reducing the difference between adjacent quantized phase values or increasing the quantization levels. The quantized phase is modulated by a specific coding sequence and then embedded into phase coding fringe patterns, thereby greatly improving the accuracy of the decoding. The coding creates multiple segments of the whole region and each segment embeds the special coding sequence. Through the corresponding decoding algorithm, the fringe order can be obtained, and following this, the absolute phase is obtained. Simulation and experimental results demonstrate the feasibility and superiority of the proposed method to measure both a single object and multiple isolated objects.

关键词： 3D measurement phase retrieval phase coding Codeword

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NLFM microwave waveform generation with increased time bandwidth product based on polarization modulation and phase coding

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OPTICAL AND QUANTUM ELECTRONICS 2022年第4期54卷 244-244页

作者： Guo, Yuxiao Wang, Muguang Mu, Hongqian Zhang, Jianyong Beijing Jiaotong Univ Minist Educ Key Lab All Opt Network & Adv Telecommun Network Inst Lightwave Technol Beijing 100044 Peoples R China

A photonic method for nonlinear frequency-modulated (NLFM) waveform generation with increased time bandwidth product (TBWP) is proposed based on polarization modulation and phase coding. A lightwave generated by a laser diode is firstly injected into a phase-coherent orthogonal lightwave generator (POLG). The POLG consists of a dual-polarization binary phase shift keying (DPBPSK) modulator and a polarization controller (PC). The DPBPSK modulator is driven by a radio frequency (RF) signal via a 90 degrees hybrid coupler. After the POLG, a pair of phase-coherent orthogonally polarized optical carriers are generated and injected into a polarization modulator (PolM) which is driven by a specially designed phase modulation signal. After another PC and a polarizer, the optical signal is detected by a photodetector and an NLFM waveform can be generated. The central frequency and bandwidth of the generated NLFM waveform can be easily adjusted by tuning the frequency of the RF signal applied to the DPBPSK modulator and the phase modulation signal applied to the PolM. The TBWP of the generated NLFM waveform can be further increased by phase coding technique. A numerical simulation is conducted to verify the proposal. The generated NLFM waveforms have a great improvement in peak-to-sidelobe ratio of the compressed pulses compared with linear frequency-modulated waveforms with the same bandwidth, duration and phase coding.

关键词： Microwave photonics Nonlinear frequency-modulated waveform phase coding Peak-to-sidelobe ratio

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Absolute phase retrieval based on spatial ternary phase coding with circular fringe projection

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OPTICS AND LASERS IN ENGINEERING 2024年 178卷

作者： Ruan, Guoshui Cao, Yiping Wu, Haitao Wei, Zhimi Li, Chengmeng Sichuan Univ Coll Elect & Informat Engn Chengdu 610065 Peoples R China

Fringe projection profilometry (FPP) based on temporal phase unwrapping (TPU) plays a vital role due to its high precision and fast speed in three-dimensional (3D) measurements. However, a fundamental contradiction arises between the necessity for numerous auxiliary patterns and the goal of enhancing measurement efficiency, particularly when ensuring a big codeword space for fringe order. Thus, a spatial ternary phase coding (STPC) method is proposed, which achieves a big codeword space by projecting just one auxiliary coding pattern while ensuring a robust decoding. By equally dividing each fringe period into several segments, ternary coding of fringe order is accomplished using an arccosine operation to code three distinct phase values within each segment. Meanwhile, circular grating is adopted due to its excellent performance in phase sensitivity, which offers a higher measuring accuracy in 3D reconstruction. Accordingly, a robust TPU is achieved by combining the introduced phase unwrapping scheme and the circle center -cosine theorem (CCCT) strategy. Furthermore, high -efficiency measurements are attained through projecting three phase -shifting circular gratings and one STPC grating, rendering it suitable for real-time measurements. Experimental results with various static objects and real-time scene demonstrate the feasibility and validity of the proposed method.

关键词： 3D measurement Fringe projection profilometry Temporal phase unwrapping phase coding Circular fringe

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A quantum study of multibit phase coding for optical storage

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IEEE JOURNAL OF QUANTUM ELECTRONICS 2006年第9-10期42卷 1001-1007页

作者： Hsu, Magnus T. L. Delaubert, Vincent Bowen, Warwick P. Fabre, Claude Bachor, Hans-A. Lam, Ping Koy Australian Natl Univ Dept Phys Australian Res Council Ctr Excellence Quantum Ato Canberra ACT 0200 Australia Univ Paris 06 Lab Kastler Brossel F-75252 Paris France Univ Otago Dept Phys Dunedin New Zealand

We propose a scheme which encodes information in both the longitudinal and spatial transverse phases of a continuous-wave optical beam. A split detector-based interferometric scheme is then introduced to optimally detect both encoded phase signals. In contrast to present day optical storage devices, our phase coding scheme has an information storage capacity which scales with the power of the read-out optical beam. We analyze the maximum number of encoding possibilities at the shot noise limit (SNL). In addition, we show that using squeezed light, the SNL can be overcome and the number of encoding possibilities increased. We discuss a possible application of our phase-coding scheme for increasing the capacities of optical storage devices.

关键词： array detection interferometer multimode optical storage phase coding quantum noise limit split detection squeezing

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Comparison of radar waveforms combining pseudo-random binary phase coding and chirp modulation for an high-frequency monostatic radar

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IET RADAR SONAR AND NAVIGATION 2016年第5期10卷 935-944页

作者： Shi, Shu-zhu Zhao, Zheng-yu Liu, Jing-nan Wuhan Univ Res Ctr Global Nav Satellite Syst Wuhan 430079 Peoples R China Wuhan Univ Sch Elect Informat Wuhan 430072 Peoples R China

Wuhan ionospheric oblique backscattering sounding system (WIOBSS) is a low-power high-frequency monostatic radar used for ionospheric sensing and aircraft detection. In this study, a novel waveform combining the pseudo-random binary phase coding (PRBPC) and the chirp modulation is proposed for this radar. Furthermore, in terms of the radar waveform requirements, four subclasses of this waveform are theoretically compared to determine which one of them is most suitable for WIOBSS, including the inter-pulse PRBPC waveform where the width of the subpulse is equal to the chirp duration, the inter-pulse PRBPC waveform where the period of the coding sequence is equal to the chirp duration, the intra-pulse PRBPC waveform where the width of the subpulse is equal to the chirp duration, and the intra-pulse PRBPC waveform where the period of the coding sequence is equal to the chirp duration. The radar waveform requirements, the ambiguity function analysis, and the performance comparison of aforementioned waveforms are described. The analysis results show that the inter-pulse PRBPC waveform where the period of the coding sequence is equal to the chirp duration has the best performance, and can achieve higher range resolution, larger signal processing gain, and better Doppler tolerance than the conventional binary phase coded waveforms.

关键词： binary codes phase coding ionospheric techniques backscatter chirp modulation Doppler radar radar resolution radar waveform requirements pseudo-random binary phase coding chirp modulation low-power high-frequency monostatic radar Wuhan ionospheric oblique backscattering sounding system WIOBSS ionospheric sensing aircraft detection interpulse PRBPC waveform coding sequence period intrapulse PRBPC waveform ambiguity function analysis range resolution signal processing gain Doppler tolerance

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A modified stepped frequency phase coding radar waveform designed for the frequency domain algorithm

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DIGITAL SIGNAL PROCESSING 2019年 88卷 101-115页

作者： Saleh, Mahdi Omar, Samir-Mohamad Grivel, Eric Bazzi, Oussama Bordeaux Univ CNRS Bordeaux INP ENSEIRBMATMECAIMSUMR 5218 Talence France Lebanese Univ Fac Sci 1 Dept Phys & Elect Beirut Lebanon Int Univ Beirut BIU Sch Engn CCE Dept Beirut Lebanon

A great deal of interest has been paid to enhance the radar range resolution for the last decades. One of the techniques is to construct a waveform combining inter-pulse and intra-pulse modulations. In this paper, stepped frequency (SF) waveform is used to represent the former, whereas phase coding (PC) is considered for the latter. To obtain the high-resolution range profile (HRRP) of a target induced by an SF waveform at the receiver, one of the approaches is the frequency domain (FD) algorithm. It has been successfully applied with SF linear frequency modulation waveforms. However, based on our investigations, processing the SFPC waveform with the FD algorithm does not lead to the performance, in terms of peak sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR), of the single-carrier phase coding (SCPC) waveform processed with a matched filter (MF). To overcome these drawbacks, we propose to split the spectrum of a phase coded pulse into a predetermined number of portions, and then to successively transmit the time-domain transformed versions of these various portions. The received echoes are then processed with a modified version of the FD algorithm. Our analysis and simulations show that the proposed waveform can be characterized by a PSLR and an ISLR close to those of the SCPC processed with MF in some scenarios. (C) 2019 Elsevier Inc. All rights reserved.

关键词： Stepped frequency waveforms phase coding Intra-pulse modulation Peak sidelobe ratio FD algorithm

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