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Terabit nonlinear frequency division multiplexing transmission desensitized to laser frequency offset and phase noise 认领 引用
1
作者 Xiang Cai Xiansong Fang +4 位作者 Jiayu Zheng Yixiao Zhu Xinyu Chen Xian Zhou Fan Zhang 《Advanced Photonics Nexus》 CSCD 2026年第2期90-99,共10页
Nonlinear frequency division multiplexing(NFDM)utilizes the nonlinear Fourier transform(NFT)to decompose signals into the nonlinear frequency domain that inherently resists fiber Kerr nonlinearity distortions.However,... Nonlinear frequency division multiplexing(NFDM)utilizes the nonlinear Fourier transform(NFT)to decompose signals into the nonlinear frequency domain that inherently resists fiber Kerr nonlinearity distortions.However,practical NFDM has been hindered by sensitivity to laser frequency offset and phase noise.In conventional NFDM receivers,a residual frequency offset typically remains before the NFT,whereas phase recovery performed after the NFT can only estimate the average phase rotation per burst,fundamentally limiting tolerance to frequency-phase impairments.In this work,we propose and experimentally demonstrate a residual carrier scheme to compensate for frequency offset and phase noise before the receiver NFT with sampling-point-level precision.Using a 3 MHz distributed feedback(DFB)laser,this scheme enables 1.0 Tb∕s PS-256 QAM NFDM transmission over 320 km,with a high spectral efficiency of 9.85 b∕s∕Hz.The Q2-factor degradation is only 0.85 dB as the total linewidth increases from 200 Hz to 3.1 MHz.The scheme achieves a Q2-factor improvement of 2.6 dB with 100 k Hz external cavity lasers and>6 dB with a 3 MHz DFB laser,compared with the conventional time-domain pilot method.To our knowledge,this is the first time NFDM demonstrates comparable tolerance to frequency-phase impairments as single-carrier systems.The proposed scheme desensitizes NFDM to frequency-phase impairments,overcoming a major barrier to practical deployment. 展开更多
关键词 nonlinear frequency division multiplexing nonlinear Fourier transform frequency offset phase noise residual carrier
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Passive phase and intensity noise suppression in optical combs via soliton self-frequency shift 认领 引用
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作者 Yuan Chen Zhuoren Wan +4 位作者 Yu Xia Min Li Kun Huang Ming Yan Heping Zeng 《Advanced Photonics Nexus》 CSCD 2026年第2期169-176,共8页
Optical frequency combs have revolutionized numerous fields of modern science,particularly precision metrology and molecular spectroscopy.However,they inherently suffer from electronic and optical noise,which restrict... Optical frequency combs have revolutionized numerous fields of modern science,particularly precision metrology and molecular spectroscopy.However,they inherently suffer from electronic and optical noise,which restricts their coherent spectral extension into critical mid-infrared and terahertz(THz)regimes,thereby demanding complex active stabilization systems.Here,we introduce a passive noise suppression technique based on the soliton self-frequency shift(SSFS)in optical fibers.Our method spectrally shifts a comb to a low-noise region,effectively isolating it from the initial parasitic optical noise and achieving simultaneous reductions of 15 dB in phase noise and 20 dB in intensity noise,as verified on a femtosecond electro-optic comb.This comb is then coherently extended into the 6 to 13μm mid-infrared range via difference-frequency generation in a GaSe crystal and into the 0.1 to 5 THz range through optical-toTHz conversion in a photoconductive antenna.Our passive noise-suppression method is broadly applicable to other comb platforms,including mode-locked lasers and on-chip microcombs,whereas the broadband comb source is promising for various spectroscopic sensing applications. 展开更多
关键词 optical frequency comb electro-optic modulation optical soliton phase noise
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Multi-phase clock generation techniques toward high-frequency and wideband applications 认领 引用
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作者 Junyan Bi Hao Xu Na Yan 《Journal of Semiconductors》 EI CAS CSCD 2026年第5期6-10,共5页
Introduction.Multi-phase clocks are widely used in modern wireline and wireless communication systems,serving as fundamental timing and phase references across diverse architectures[1-4].As data rates and carrier freq... Introduction.Multi-phase clocks are widely used in modern wireline and wireless communication systems,serving as fundamental timing and phase references across diverse architectures[1-4].As data rates and carrier frequencies continue to scale,both the required phase count and operating frequency have increased substantially,pushing conventional clock generation techniques toward their fundamental limits. 展开更多
关键词 wideband applications clock generation techniques multi phase clocks wireline communication wireline wireless communication systemsserving high frequency phase references wireless communication
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Super-resolution optical frequency domain reflectometry based on spectral phase shift convolution 认领 引用
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作者 Kaijun Liu Guolu Yin +2 位作者 Junping Zhang Liuxi Chen Tao Zhu 《Advanced Photonics Nexus》 CSCD 2026年第4期71-79,共9页
For the traditional optical frequency domain reflectometry(OFDR)technology based on the crosscorrelation demodulation algorithm,there is a mutual limitation between its sensing spatial resolution and sensing accuracy.... For the traditional optical frequency domain reflectometry(OFDR)technology based on the crosscorrelation demodulation algorithm,there is a mutual limitation between its sensing spatial resolution and sensing accuracy.This restriction makes it challenging to achieve resolutions at the micron scale.We propose a spectral phase shift convolution demodulation scheme for OFDR to overcome the limitations of sensing spatial resolution and sensing accuracy,achieving wavelength super-resolution sensing.Through theoretical analysis,we identified the limitations of traditional cross-correlation demodulation algorithms regarding wavelength and spatial resolution,as well as the positioning errors for correlation peaks.By leveraging the phase-shifting properties,we transformed the peak-finding into a zero-finding problem.Furthermore,we employed fast Fourier transform interpolation and linear interpolation near the zeros to achieve precise localization of the correlation delay.Through theoretical simulations and experiments,the error evolution patterns of the algorithm under uniform strain and sinusoidal strain distributions were investigated,and it was demonstrated that a high signal-to-noise ratio environment helps improve demodulation accuracy.Strain experiments validated a sensing spatial resolution on the order of 350μm and a sensing accuracy of∼3.5με.In addition,shape reconstruction was achieved through standard 2D semicircular shape reconstruction experiments at a spatial resolution of 350μm,with only a 0.33%reconstruction error.We propose a new direction for correlation demodulation schemes,which have promising applications in fields such as medical devices and hyper-continuum robot shape sensing requiring ultra-high spatial resolution. 展开更多
关键词 super-resolution measurement optical frequency domain reflectometer distributed strain sensing phase shift convolution
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Frequency measurement and analysis via different frequency phase synchronization fuzzy region 认领 引用
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作者 DU Baoqiang WANG Xiang YAO Dunzhi 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2026年第2期219-231,共13页
A precise frequency measurement and analysis method utilizing the concept of the different frequency phase synchronization fuzzy region is presented based on the principle of phase synchronization detection.Initially,... A precise frequency measurement and analysis method utilizing the concept of the different frequency phase synchronization fuzzy region is presented based on the principle of phase synchronization detection.Initially,the frequency of the measured signal was roughly estimated by using the traditional high-precision time and frequency detection technology.Subsequently,the frequency estimated was fed into a direct digital synthesizer(DDS)to generate a real-time frequency standard signal that exhibited a slight frequency deviation relative to the measured signal.The edge pulses of the different frequency phase synchronization fuzzy region served as counter switch signals,enabling the counting of both the detected signal and the real-time frequency standard signal within a specified gate time.Through subsequent data processing of the obtained values,the frequency,frequency difference,and frequency accuracy of the detected signal could be determined.Experimental results demonstrate that the system based on this method achieves a frequency stability of 10−13 at 1 s,with a frequency deviation of less than 3 Hz.Compared with traditional frequency measurement and analysis methods,this approach has many advantages,especially its fast response time of less than 1 ms,high measurement accuracy of more than 10−11 at 1 s,high integration with only one FPGA chip,and cost of less than 1000 yuan.It is widely applied in the fields of time and frequency services and security technology of the Beidou satellite(BDS)navigation system,such as BDS pseudo-range measurement,Beidou positioning,navigation and time services,as well as precise time and frequency measurement and control,etc. 展开更多
关键词 different frequency phase synchronization frequency analysis and measurement frequency accuracy phase synchronization fuzzy region frequency stability group period
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Magnetic-Dielectric Synergy in One-Dimensional Metal Heterostructures for Enhanced Low-Frequency Microwave Absorption 认领 引用 被引量：3
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作者 Feiyue Hu Peigen Zhang +10 位作者 Pei Ding Shuo Zhang Bingbing Fan Ali Saffar Shamshirgar Wei Zheng Wenwen Sun Longzhu Cai Haijiao Xie Qiyue Shao Johanna Rosen ZhengMing Sun 《Nano-Micro Letters》 SCIE EI CAS CSCD 2026年第5期371-390,共20页
Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promisin... Microwave absorption(MA)materials often face poor synergy between impedance matching and attenuation in the low-frequency range.Balancing permittivity and permeability through magnetic-dielectric synergy is a promising strategy to address this issue.To realize the synergy,herein,Sn whiskers with an in situ oxide layer served as substrates for magnetic-loss-active CoNi nanosheet growth,forming a hierarchical CoNi@SnO2@Sn(CNS)heterostructure.The CNS absorber achieves a minimum reflection loss(RLmin)value of-62.29 dB with an effective absorption bandwidth(EAB)of 2.2 GHz,covering the entire C-band with 70%absorption at only 2.61 mm thickness.The nanosheet design of CoNi enhances magnetic anisotropy to promote natural resonance,while the conductive Sn core and abundant Sn/SnO2 and CoNi/SnO2 heterointerfaces facilitate conduction loss and dielectric polarization.When composited into a thermoplastic polyurethane(TPU)matrix,the resulting CNS/TPU-2 film(20 wt%CNS)exhibits an RLmin value of-61.04 dB and a 2.5 GHz EAB.Its in-plane and through-plane thermal conductivities reach 2.41 and 0.51 W m-1 K-1,representing 4.1 and 2.6 times those of pure TPU films,respectively,facilitating heat dissipation from protected devices.This work provides valuable insights into magnetic-dielectric synergy for low-frequency MA of 1D metal-based materials,offering promising potential for 5G communications and flexible electronics. 展开更多
关键词 Low frequency microwave absorption Magnetic-dielectric synergy MAX phase CoNi@SnO2@Sn heterostructure Thermal conductivity
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Research on anti-active mainlobe interference methods for frequency diverse array radar 认领 引用
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作者 WANG Bo LI Yonglin +2 位作者 WANG Gang YANG Rennong ZHAO Yu 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2026年第2期455-466,共12页
In environments with complex electromagnetic characteristics,signals from active repeater mainlobe deception jamming are closely aligned with radar emissions,significantly impairing radar functionality.This paper expl... In environments with complex electromagnetic characteristics,signals from active repeater mainlobe deception jamming are closely aligned with radar emissions,significantly impairing radar functionality.This paper explores the efficacy of frequency diverse array(FDA)radar in combating active mainlobe jamming.Initially,the signal model for FDA multi-input multioutput(FDA-MIMO)radar is introduced.Building on this,a frequency offset optimization approach for FDA radar using the differential artificial bee colony(DEABC)algorithm is developed.Following this,the steepest descent linear minimum variance distortionless response beamforming algorithm is implemented in an FDA early warning radar to mitigate mainlobe jamming.Simulations are conducted to validate the effectiveness of the proposed strategies.The results from these simulations demonstrate that the methodologies can create a focused beam aimed at the target while effectively neutralizing jamming signals within the mainlobe area. 展开更多
关键词 frequency diverse array(FDA) phased array radar active jamming mainlobe jamming
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Fast-Lock Low-Jitter PLL with a Simple Phase-Frequency Detector 认领 引用 被引量：4
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作者 陈莹梅 王志功 章丽 《Journal of Semiconductors》 CAS 北大核心 2008年第1期88-92,共5页
A fast-locking, low-jitter, phase-locked loop （PLL） with a simple phase-frequency detector is proposed. The phase-frequency detector is composed of only two XOR gates. It simultaneously achieves low jitter and short... A fast-locking, low-jitter, phase-locked loop （PLL） with a simple phase-frequency detector is proposed. The phase-frequency detector is composed of only two XOR gates. It simultaneously achieves low jitter and short locking time. The voltage-controlled oscillator within the PLL consists of four-stage ring oscillators which are coupled to each other and oscillate with the same frequency and a phase shift of 45. The PLL is fabricated in 0. 1Stem CMOS technology. The measured phase noise of the PLL output at 500kHz offset from the 5GHz center frequency is - 102.6dBc/Hz. The circuit exhibits a capture range of 280MHz and a low RMS jitter of 2.06ps. The power dissipation excluding the output buffers is only 21.6roW at a 1.8V supply. 展开更多
关键词 phase locked loop phase-frequency detector voltage-controlled oscillator jitter locking time
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Robust CMOS phase frequency detector for high speed and low jitter charge pump PLL 认领 引用 被引量：2
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作者 周建政 王志功 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期15-19,共5页
In order to improve the performance of the existing phase frequency detectors （PFDs）, a systematical analysis of the existing PFDs is presented. Based on the circuit architecture, both classifications and comparison... In order to improve the performance of the existing phase frequency detectors （PFDs）, a systematical analysis of the existing PFDs is presented. Based on the circuit architecture, both classifications and comparisons are made. A new robust CMOS phase frequency detector for a high speed and low jitter charge pump phrase-locked loop （PLL） is designed. The proposed PFD consists of two rising-edge triggered dynamic D flip-flops, two positive-edge detectors and delaying units and two OR gates. It adopts two reset mechanisms to avoid the LIP and DN signals to be logic-1 simultaneously. Thus, any current mismatch of the charge pump circuit will not worsen the performance of the PLL. Furthermore, it has hardly any dead-zone phenomenon in phase characteristic. Simulations with ADS are performed based on a TSMC 0. 18-μm CMOS process with a 1.8-V supply voltage. According to the theoretical analyses and simulation results, the proposed PFD shows a satisfactory performance with a high operation frequency （≈ 1 GHz）, a wide phase-detection range [ ± 2π], a near zero dead-zone （ 〈 0. 1 ps）, high reliability, low phase jitter, low power consumption （ ≈100 μW） and small circuit complexity. 展开更多
关键词 phase frequency detectors dead-zone blind-zone phase characteristic frequency characteristic
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Design of 0.5V low-voltage phase and frequency detector for frequency synthesizer in wireless sensor networks 认领 引用
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作者 王利丹 李智群 李伟 《Journal of Southeast University(English Edition)》 EI CAS 2011年第1期8-12,共5页
Based on 0.13μm complementary metal-oxide-semiconductor（CMOS） technology,a phase and frequency detector（PFD） is designed with a low supply voltage of 0.5V for frequency synthesizers used in wireless sensor netwo... Based on 0.13μm complementary metal-oxide-semiconductor（CMOS） technology,a phase and frequency detector（PFD） is designed with a low supply voltage of 0.5V for frequency synthesizers used in wireless sensor networks（WSNs）.The PFD can compare the frequency and phase differences of input signals and deliver a signal voltage proportional to the difference.Low threshold transistors are used in the circuits since a power supply of 0.5V is adopted.A pulse latched structure is also used in the circuits in order to increase both the detection range of phase errors and the maximum operation frequency.In experiments,a phase error with a range from-358° to 358° is measured when the input signal frequency is 2MHz.The PFD has a faster acquisition speed compared with conventional digital PFDs.When the input signals are at a frequency of 2MHz with zero phase error,the circuits have a power consumption of 1.8[KG＊8]μW,and the maximum operation frequency is 1.25GHz. 展开更多
关键词 phase and frequency detector（PFD） low threshold transistor pulse latch
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Lattice Anchoring Stabilizesα-FAPbI3 Perovskite for High-Performance X-Ray Detectors 认领 引用 被引量：3
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作者 Yu-Hua Huang Su-Yan Zou +5 位作者 Cong-Yi Sheng Yu-Chuang Fang Xu-Dong Wang Wei Wei Wen-Guang Li Dai-Bin Kuang 《Nano-Micro Letters》 SCIE EI CAS CSCD 2026年第1期337-354,共18页
Formamidinium lead iodide(FAPbI3)perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection appl... Formamidinium lead iodide(FAPbI3)perovskite exhibits an impressive X-ray absorption coefficient and a large carrier mobility-lifetime product(μτ),making it as a highly promising candidate for X-ray detection application.However,the presence of larger FA+cation induces to an expansion of the Pb-I octahedral framework,which unfortunately affects both the stability and charge carrier mobility of the corresponding devices.To address this challenge,we develop a novel low-dimensional(HtrzT)PbI3 perovskite featuring a conjugated organic cation(1H-1,2,4-Triazole-3-thiol,HtrzT+)which matches well with theα-FAPbI3 lattices in two-dimensional plane.Benefiting from the matched lattice between(HtrzT)PbI3 andα-FAPbI3,the anchored lattice enhances the Pb-I bond strength and effectively mitigates the inherent tensile strain of theα-FAPbI3 crystal lattice.The X-ray detector based on(HtrzT)PbI3(1.0)/FAPbI3 device achieves a remarkable sensitivity up to 1.83×105μC Gyair−1 cm−2,along with a low detection limit of 27.6 nGyair s−1,attributed to the release of residual stress,and the enhancement in carrier mobility-lifetime product.Furthermore,the detector exhibits outstanding stability under X-ray irradiation with tolerating doses equivalent to nearly 1.17×106 chest imaging doses. 展开更多
关键词 α-FAPbI3perovskite Conjugated organic cation Lattice anchoring Phase stability X-ray detectors
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A super-high resolution frequency standard measuring approach based on phase coincidence characteristics between signals 认领 引用 被引量：14
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作者 李智奇 周渭 +1 位作者 陈发喜 刘晨光 《Chinese Physics B》 SCIE EI CAS 2010年第9期287-290,共4页
A method for super high resolution comparison measurement is proposed in this paper with a comparison between the frequency standards of different nominal frequencies, which is based on phase coincidence detection of ... A method for super high resolution comparison measurement is proposed in this paper with a comparison between the frequency standards of different nominal frequencies, which is based on phase coincidence detection of the two compared signals. It utilizes the regular phase shift characteristics between the signals. The resolution of the measurement approach can reach 10^-13/s at 5 MHz, and the self-calibration resolution can achieve 10^-14/s in the comparison between 10 MHz and 100 MHz, or even can reach 10^-15/s in the comparison between 10 MHz and 190 MHz. This method implies significant progress in the development of the high precision frequency standard comparison technology. 展开更多
关键词 frequency measurement resolution phase coincidence equivalent phase comparison frequency
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Microwave frequency transfer over a 112-km urban fiber link based on electronic phase compensation 认领 引用 被引量：6
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作者 Wen-Xiang Xue Wen-Yu Zhao +4 位作者 Hong-Lei Quan Cui-Chen Zhao Yan Xing Hai-Feng Jiang Shou-Gang Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第6期207-211,共5页
We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the l... We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the low noise frequency divider by 4 to differentiate the frequency of the forward signal from that of the backward one,thus suppressing the effect of Brillouin backscattering and parasitic reflection along the link.In terms of overlapping Allan deviation,the frequency transfer instability of 4.2×10-15 at 1-s integration time and 1.6×10-18 at one-day integration time was achieved.In addition,its sensitivity to the polarization mode dispersion in fiber is analyzed by comparing the results with and without laser polarization scrambling.Generally,with simplicity and robustness,the system can offer great potentials in constructing cascaded frequency transfer system and facilitate the building of fiber-based microwave transfer network. 展开更多
关键词 microwave frequency transfer phase compensation polarization mode dispersion
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Cognitive anti-jamming receiver under phase noise in high frequency bands 认领 引用 被引量：2
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作者 FANG Zheng LI Haitao QIAN Yiming 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2018年第1期31-38,共8页
This paper investigates the jamming sensing performance of the simultaneous transmit and receive based cognitive anti-jamming(SCAJ) receiver impaired by phase noise in local oscillators(LO) over fading channels. First... This paper investigates the jamming sensing performance of the simultaneous transmit and receive based cognitive anti-jamming(SCAJ) receiver impaired by phase noise in local oscillators(LO) over fading channels. Firstly, energy detection(ED)based on the jamming to noise ratio(JNR) of the high frequency bands SCAJ receiver with phase noise under different channels is analyzed. Then, the probabilities of jamming detection and false alarm in closed-form for the SCAJ receiver are derived. Finally,the modified Bayesian Cramer-Rao bound(BCRB) of jamming sensing for the SCAJ receiver is presented. Simulation results show that the performance degradation of the SCAJ system due to phase noise is more severe than that due to the channel fading in the circumstances where the signal bandwidth(BW) is kept a constant. Moreover, the signal BW has an effect on the phase noise in LO, and the jamming detection probability of the wideband SCAJ receiver with lower phase noise outperforms that of the narrowband receiver using the same center frequency. Furthermore,an accurate phase noise estimation and compensation scheme can improve the jamming detection capability of the SCAJ receiver in high frequency bands and approach to the upper bound. 展开更多
关键词 high frequency band simultaneous transmit and receive phase noise cognitive anti-jamming
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Frequency Domain Filtering SAR Interferometric Phase Noise Using the Amended Matrix Pencil Model 认领 引用 被引量：2
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作者 Yandong Gao Shubi Zhang +1 位作者 Kefei Zhang Shijin Li 《Computer Modeling in Engineering & Sciences》 SCIE EI 2019年第5期349-363,共15页
Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions... Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions. Moreover, the InSAR/SAR datarange is relatively large, so the efficiency of interferential phase filtering is one of themajor problems. In this letter, we proposed an interferometric phase filtering methodbased on an amended matrix pencil and linear window mean filter. The combination ofthe matrix pencil and the linear mean filter are introduced to the interferometric phasefiltering for the first time. First, the interferometric signal is analyzed, and theinterferometric phase filtering is transformed into a local frequency estimation problem.Then, the local frequency is estimated using an amended matrix pencil at a window. Thelocal frequency can represent terrain changes, thus suggesting that the frequency can beaccurately estimated even in dense fringe regions. Finally, the local frequency is filteredby using a linear window mean filter, and the filtered phase is recovered. The proposedmethod is calculated by some matrices. Therefore, the computational complexity isreduced, and the efficiency of the interferometric phase filtering is improved.Experiments are conducted with simulated and real InSAR data. The proposed methodexhibits a better filtering effect and an ideal efficiency as compared with the traditionalfiltering method. 展开更多
关键词 Interferometric phase filtering interferometric synthetic aperture radar local frequency estimation amended matrix pencil linear window mean filter
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An improved frequency shift method for ATI-SAR flat earth phase removal 认领 引用 被引量：1
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作者 Yubin Zhang Jie Zhang +1 位作者 Junmin Meng Chenqing Fan 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2019年第8期94-100,共7页
An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shif... An improved frequency shift method is proposed to remove the flat earth phase in ATI-SAR ocean surface motion detection in this study. First, two conventional flat earth effect removal methods(i.e., the frequency shift method and the orbital parameter method) are introduced and compared. Then, two improvements to frequency shift method are suggested. In the first improvement, the phase diagram is divided into several sub-blocks to calculate the phase fringe frequency. In the second improvement, a function between the phase of land regions and position is fitted to correct the residual flat earth phase based on the phase of the land regions that tend toward zero in an along-track interferogram. It is found that the improved frequency shift method is greatly improved;and it agrees well with the orbital parameter method, and achieves similar accuracy. 展开更多
关键词 flat earth phase ATI-SAR frequency shift orbital parameter
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OSCILLATION FREQUENCY THEORY OF A PIEZOELECTRIC SENSOR INLIQUID PHASE WITH TWO SEPARATED-ELECTRODES 认领 引用 被引量：1
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作者 Da Zhong SHEN Ze Chang LIU +1 位作者 Qing KANG Jind Tian HU 《Chinese Chemical Letters》 SCIE CAS 1996年第2期169-172,共4页
In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liqu... In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liquid properties are investigated. 展开更多
关键词 SENSOR FREQUENCY INLIQUID OF OSCILLATION PHASE PIEZOELECTRIC ELECTRODES SEPARATED THEORY
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Adaptive compensating method for Doppler frequency shift using LMS and phase estimation 认领 引用 被引量：7
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作者 Jing Qingfeng Guo Qing 《Journal of Systems Engineering and Electronics》 SCIE EI 2009年第5期913-919,共7页
The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the ph... The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the phase offsets due to frequency shift are linear. Based on this premise, the compensation processes are： firstly, the phase offsets between the baseband neighbor-symbols after clock recovery is unbiasedly estimated among the reference symbols; then, the receiving signals symbols are adjusted by the phase estimation value; finally, the phase offsets after adjusting are compensated by the least mean squares （LMS） algorithm. In order to express the compensation processes and ability clearly, the quadrature phase shift keying （QPSK） modulation signals are regarded as examples for Matlab simulation. BER simulations are carried out using the Monte-Carlo method. The learning curves are obtained to study the algorithm＇s convergence ability. The constellation figures are also simulated to observe the compensation results directly. 展开更多
关键词 Doppler frequency shift least mean square minimum phase shift keying unbiased estimation Matlab simulation.
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Relative phase locking of a terahertz laser system configured with a frequency comb and a single-mode laser 认领 引用 被引量：4
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作者 Wen Guan Ziping Li +8 位作者 Shumin Wu Han Liu Xuhong Ma Yiran Zhao Chenjie Wang Binbin Liu Zhenzhen Zhang Juncheng Cao Hua Li 《Advanced Photonics Nexus》 2023年第2期94-104,共11页
Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electri... Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electrical and/or optical injection and phase locking.However,these techniques normally involve complex experimental facilities.Therefore,an easy implementation of the stability evaluation of a laser is still challenging,especially for lasers emitting in the terahertz(THz)frequency range because the broadband photodetectors and mature locking techniques are limited.In this work,we propose a simple method,i.e.,relative phase locking,to quickly evaluate the stability of THz lasers without a need of a THz local oscillator.The THz laser system consists of a THz quantum cascade laser(QCL)frequency comb and a single-mode QCL.Using the single-mode laser as a fast detector,heterodyne signals resulting from the beating between the singlemode laser and the comb laser are obtained.One of the heterodyne beating signals is selected and sent to a phase-locked loop(PLL)for implementing the relative phase locking.Two kinds of locks are performed by feeding the output error signal of the PLL,either to the comb laser or to the single-mode laser.By analyzing the current change and the corresponding frequency change of the PLL-controlled QCL in each phase-locking condition,we,in principle,are able to experimentally compare the stability of the emission frequency of the single-mode QCL(f s)and the carrier envelope offset frequency(f CEO)of the QCL comb.The experimental results reveal that the QCL comb with the repetition frequency injection locked demonstrates much higher stability than the single-mode laser.The work provides a simple heterodyne scheme for understanding the stability of THz lasers,which paves the way for the further locking of the lasers and their high-precision applications in the THz frequency range. 展开更多
关键词 terahertz quantum cascade laser frequency comb phase lock
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Modulation Recognition with Frequency Offset and Phase Offset over Multipath Channels 认领 引用 被引量：1
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作者 Mingqian Liu Zhaoxi Wen +1 位作者 Yunfei Chen Ming Li 《China Communications》 SCIE CSCD 2023年第10期58-69,共12页
Modulation recognition becomes unreliable at low signal-to-noise ratio(SNR)over fading channel.A novel method is proposed to recognize the digital modulated signals with frequency and phase offsets over multi-path fad... Modulation recognition becomes unreliable at low signal-to-noise ratio(SNR)over fading channel.A novel method is proposed to recognize the digital modulated signals with frequency and phase offsets over multi-path fading channels in this paper.This method can overcome the effects of phase offset,Gaussian noise and multi-path fading.To achieve this,firstly,the characteristic parameters search is constructed based on the cyclostationarity of received signals,to overcome the phase offset,Gaussian white noise,and influence caused by multi-path fading.Then,the carrier frequency of the received signal is estimated,and the maximum characteristic parameter is searched around the integer multiple carriers and their vicinities.Finally,the modulation types of the received signal with frequency and phase offsets are classified using decision thresholds.Simulation results demonstrate that the performance of the proposed method is better than the traditional methods when SNR is over 5dB,and that the proposed method is robust to frequency and phase offsets over multipath channels. 展开更多
关键词 cyclic characteristics frequency and phase offset multi-path channels modulation recognition
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