For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform ...For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform （FRFT） is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.展开更多
As modern electromagnetic environments are more and more complex,the anti-interference performance of the synchronization acquisition is becoming vital in wireless communications.With the rapid development of the digi...As modern electromagnetic environments are more and more complex,the anti-interference performance of the synchronization acquisition is becoming vital in wireless communications.With the rapid development of the digital signal processing technologies,some synchronization acquisition algorithms for hybrid direct-sequence(DS)/frequency hopping(FH)spread spectrum communications have been proposed.However,these algorithms do not focus on the analysis and the design of the synchronization acquisition under typical interferences.In this paper,a synchronization acquisition algorithm based on the frequency hopping pulses combining(FHPC)is proposed.Specifically,the proposed algorithm is composed of two modules:an adaptive interference suppression(IS)module and an adaptive combining decision module.The adaptive IS module mitigates the effect of the interfered samples in the time-domain or the frequencydomain,and the adaptive combining decision module can utilize each frequency hopping pulse to construct an anti-interference decision metric and generate an adaptive acquisition decision threshold to complete the acquisition.Theory and simulation demonstrate that the proposed algorithm significantly enhances the antiinterference and anti-noise performances of the synchronization acquisition for hybrid DS/FH communications.展开更多
Under sensorless control, the position estimation error in interior permanent magnet(PM) synchronous machines will lead to parameter identification errors and a rank-deficiency issue. This paper proposes a parameter i...Under sensorless control, the position estimation error in interior permanent magnet(PM) synchronous machines will lead to parameter identification errors and a rank-deficiency issue. This paper proposes a parameter identification model that is independent of position error by combining the dq-axis voltage equations. Then, a novel dual signal alternate injection method is proposed to address the rank-deficiency issue, i.e., during one injection period, a zero, positive, and negative d-axis current injection together with a rotor position offset injection, to simultaneously identify the multi-parameters, including stator resistance, dq-axis inductances, and PM flux linkage. The proposed method is verified by experiments at different dq-axis current conditions.展开更多
Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the ...Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the locally optimal estimation scheme, the optimal testing searches and the locally optimal testing scheme. In the four kinds of parallel acquisition schemes, the expressions for the probability of error are given and compared with the actual error probabilities obtained via Monte Carlo simulation. We also outline a technique that can be suboptimal because of a large amount of hardware and computation when using the parallel acquisition schemes.展开更多
在深层油气藏勘探中,地震波能量屏蔽现象(如煤层、膏盐层等)严重制约了深部目标层反射信号的清晰度,单一地震属性难以全面表征复杂地质条件。时频电磁法(Time Frequency Electromagnetic Method,TFEM)基于电磁波在不同地质体传播差异,...在深层油气藏勘探中,地震波能量屏蔽现象(如煤层、膏盐层等)严重制约了深部目标层反射信号的清晰度,单一地震属性难以全面表征复杂地质条件。时频电磁法(Time Frequency Electromagnetic Method,TFEM)基于电磁波在不同地质体传播差异,可有效穿透高阻、高速屏蔽层,在深部岩石属性探测与储层预测中具有独特的穿透能力。近年来该技术在深层油气勘探方面取得突破:研发了新一代发射系统;创新地提出双侧激发多线同步采集技术和四方位全覆盖同步激发采集技术,显著改善了照明均匀性,降低了阴影效应与各向异性影响。在处理技术方面,创新地提出了一种分步递进反演策略,这种方法核心在于构建多源数据协同约束与分步递进反演策略,通过渐进式优化,实现反演精度的层级提升。理论正反演模拟验证了方法的合理性与有效性,并在中国西部塔里木盆地8000 m超深井储层预测及东部深层火成岩储层评价中取得了显著的应用成效。展开更多
Correction to:Radiation Detection Technology and Methods(2024)8:1486-1495.https://doi.org/10.1007/s41605-024-00470-z.In this article Methods section of the publication,the term(beamline scientific data acquisition sys...Correction to:Radiation Detection Technology and Methods(2024)8:1486-1495.https://doi.org/10.1007/s41605-024-00470-z.In this article Methods section of the publication,the term(beamline scientific data acquisition system)is incorrectly written and redundant,it has been removed.展开更多
The fixed frame length maximum correlation method which is the optimum methodover the binary symmetric channel has been proved.With Poisson distribution,the frame syncacquisition probability is obtained and followed b...The fixed frame length maximum correlation method which is the optimum methodover the binary symmetric channel has been proved.With Poisson distribution,the frame syncacquisition probability is obtained and followed by computer simulation.By Markov modelingtechniques,the probability and the mean time into lock mode are given.Finally,it is shown thatthe optimum frame sync method is far superior to conventional,and it is very useful in practice.展开更多
In this paper, based on an adaptive chaos synchronization scheme, two methods of encoding-decoding message for secure communication are proposed. With the first method, message is directly added to the chaotic signal ...In this paper, based on an adaptive chaos synchronization scheme, two methods of encoding-decoding message for secure communication are proposed. With the first method, message is directly added to the chaotic signal with parameter uncertainty. In the second method, multi-parameter modulation is used to simultaneously transmit more than one digital message （i.e., the multichannel digital communication） through just a single signal, which switches among various chaotic attractors that differ only subtly. In theory, such a treatment increases the difficulty for the intruder to directly intercept the information, and meanwhile the implementation cost decreases significantly. In addition, numerical results show the methods are robust against weak noise, which implies their practicability.展开更多
This paper considers the case of smart antennas and multiple inputs multiple outputs (MIMO) systems, suited for the radio access of 3G mobile communications, involving two-dimensional spatio-temporal signal processing...This paper considers the case of smart antennas and multiple inputs multiple outputs (MIMO) systems, suited for the radio access of 3G mobile communications, involving two-dimensional spatio-temporal signal processing and two-dwell procedures. The main novelty of our work is twofold: first, a two-dwell acquisition technique is here performed to save the mean acquisition time versus one-dwell acquisition techniques;sec-ond, the searching procedure is driven from the estimates of the local signal-to-interference-plus-noise ratio, reducing again the mean acquisition time. Some examples of application to the detection of 3G communication signals in typical mobile scenarios are provided and we have verified the effectiveness of the analyzed spatio-temporal two-dwell procedures. The presented technique seems to constitute a promising tool for analytic setting of near optimum spatio-temporal acquisition testing procedures based on serial search/veri-fication modes.展开更多
基金supported by the National Natural Science Foundation of China(60672047).
文摘For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform （FRFT） is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.
基金supported in part by the National Natural Science Foundation of China (NSFC) under Grants 62131005, 62071096in part by the Fundamental Research Funds for the Central Universities under Grant 2242022k60006+1 种基金in part by the National NSFC under Grant U19B2014in part by the Natural Science Foundation of Sichuan under Grant 2022NSFSC0495
文摘As modern electromagnetic environments are more and more complex,the anti-interference performance of the synchronization acquisition is becoming vital in wireless communications.With the rapid development of the digital signal processing technologies,some synchronization acquisition algorithms for hybrid direct-sequence(DS)/frequency hopping(FH)spread spectrum communications have been proposed.However,these algorithms do not focus on the analysis and the design of the synchronization acquisition under typical interferences.In this paper,a synchronization acquisition algorithm based on the frequency hopping pulses combining(FHPC)is proposed.Specifically,the proposed algorithm is composed of two modules:an adaptive interference suppression(IS)module and an adaptive combining decision module.The adaptive IS module mitigates the effect of the interfered samples in the time-domain or the frequencydomain,and the adaptive combining decision module can utilize each frequency hopping pulse to construct an anti-interference decision metric and generate an adaptive acquisition decision threshold to complete the acquisition.Theory and simulation demonstrate that the proposed algorithm significantly enhances the antiinterference and anti-noise performances of the synchronization acquisition for hybrid DS/FH communications.
文摘Under sensorless control, the position estimation error in interior permanent magnet(PM) synchronous machines will lead to parameter identification errors and a rank-deficiency issue. This paper proposes a parameter identification model that is independent of position error by combining the dq-axis voltage equations. Then, a novel dual signal alternate injection method is proposed to address the rank-deficiency issue, i.e., during one injection period, a zero, positive, and negative d-axis current injection together with a rotor position offset injection, to simultaneously identify the multi-parameters, including stator resistance, dq-axis inductances, and PM flux linkage. The proposed method is verified by experiments at different dq-axis current conditions.
文摘Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the locally optimal estimation scheme, the optimal testing searches and the locally optimal testing scheme. In the four kinds of parallel acquisition schemes, the expressions for the probability of error are given and compared with the actual error probabilities obtained via Monte Carlo simulation. We also outline a technique that can be suboptimal because of a large amount of hardware and computation when using the parallel acquisition schemes.
文摘在深层油气藏勘探中,地震波能量屏蔽现象(如煤层、膏盐层等)严重制约了深部目标层反射信号的清晰度,单一地震属性难以全面表征复杂地质条件。时频电磁法(Time Frequency Electromagnetic Method,TFEM)基于电磁波在不同地质体传播差异,可有效穿透高阻、高速屏蔽层,在深部岩石属性探测与储层预测中具有独特的穿透能力。近年来该技术在深层油气勘探方面取得突破:研发了新一代发射系统;创新地提出双侧激发多线同步采集技术和四方位全覆盖同步激发采集技术,显著改善了照明均匀性,降低了阴影效应与各向异性影响。在处理技术方面,创新地提出了一种分步递进反演策略,这种方法核心在于构建多源数据协同约束与分步递进反演策略,通过渐进式优化,实现反演精度的层级提升。理论正反演模拟验证了方法的合理性与有效性,并在中国西部塔里木盆地8000 m超深井储层预测及东部深层火成岩储层评价中取得了显著的应用成效。
文摘Correction to:Radiation Detection Technology and Methods(2024)8:1486-1495.https://doi.org/10.1007/s41605-024-00470-z.In this article Methods section of the publication,the term(beamline scientific data acquisition system)is incorrectly written and redundant,it has been removed.
文摘The fixed frame length maximum correlation method which is the optimum methodover the binary symmetric channel has been proved.With Poisson distribution,the frame syncacquisition probability is obtained and followed by computer simulation.By Markov modelingtechniques,the probability and the mean time into lock mode are given.Finally,it is shown thatthe optimum frame sync method is far superior to conventional,and it is very useful in practice.
基金Project supported by the National Natural Science Foundation of China （Grant No. 10572080）, Shanghai Rising-Star Program （Grant No.05QMX1422）, and Dawn Project of the Science Foundation of Shanghai Municipal Commission of Education （Grant No.05SG41 04YQHB089）
文摘In this paper, based on an adaptive chaos synchronization scheme, two methods of encoding-decoding message for secure communication are proposed. With the first method, message is directly added to the chaotic signal with parameter uncertainty. In the second method, multi-parameter modulation is used to simultaneously transmit more than one digital message （i.e., the multichannel digital communication） through just a single signal, which switches among various chaotic attractors that differ only subtly. In theory, such a treatment increases the difficulty for the intruder to directly intercept the information, and meanwhile the implementation cost decreases significantly. In addition, numerical results show the methods are robust against weak noise, which implies their practicability.
文摘This paper considers the case of smart antennas and multiple inputs multiple outputs (MIMO) systems, suited for the radio access of 3G mobile communications, involving two-dimensional spatio-temporal signal processing and two-dwell procedures. The main novelty of our work is twofold: first, a two-dwell acquisition technique is here performed to save the mean acquisition time versus one-dwell acquisition techniques;sec-ond, the searching procedure is driven from the estimates of the local signal-to-interference-plus-noise ratio, reducing again the mean acquisition time. Some examples of application to the detection of 3G communication signals in typical mobile scenarios are provided and we have verified the effectiveness of the analyzed spatio-temporal two-dwell procedures. The presented technique seems to constitute a promising tool for analytic setting of near optimum spatio-temporal acquisition testing procedures based on serial search/veri-fication modes.
