共查询到20条相似文献,搜索用时 15 毫秒
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V. I. Kostylev 《Radiophysics and Quantum Electronics》2002,45(5):411-418
We find the distribution of the decision statistic of a discrete energy detector in the case of reception of the superposition of white noise and a quasideterministic signal with a non-Rayleigh distribution of amplitude fluctuations. An expression for the true-detection probability is derived. 相似文献
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We find the decision-statistic distribution of an adaptive trained energy detector. Expressions for the probabilities of false alarm and true detection are obtained. 相似文献
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We present a scheme to generate a maximally entangled state of two three-level atoms in a cavity. The success or failure of the generation of the desired entangled state can be determined by detecting the polarization of the photon leaking out of the cavity. With the use of an automatic feedback, the success probability of the scheme can be made to approach unity. 相似文献
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Following the procedure of noncommutative tomography of analytic signals, some typical radio signals are analyzed. Tomograms of rectangular pulses, delta-pulses, and Gaussian signals are presented. Properties of the noncommutative tomography method are discussed. 相似文献
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Leak Detection of Gas Pipelines Based on Characteristics of Acoustic Leakage and Interfering Signals
When acoustic method is used in leak detection for natural gas pipelines, the external interferences including operation of compressor and valve, pipeline knocking, etc., should be distinguished with acoustic leakage signals to
improve the accuracy and reduce false alarms. In this paper, the technologies of extracting characteristics of acoustic signals were summarized. The acoustic leakage signals and interfering signals were measured by experiments and the
characteristics of time-domain, frequency-domain and time-frequency domain were extracted. The main characteristics of time-domain are mean value, root mean square value, kurtosis, skewness and correlation function, etc. The features in frequency domain were obtained by frequency spectrum analysis and power spectrum density, while time-frequency analysis was accomplished by short time Fourier transform. The results show that the external interferences can be removed effectively by the characteristics of time domain, frequency domain and time-frequency domain. It can be drawn that the acoustic leak detection method can be applied to natural gas pipelines and the characteristics can help reduce false alarms and missing alarms. 相似文献
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O. V. Bolkhovskaya A. A. Mal'tsev K. V. Rodyushkin 《Radiophysics and Quantum Electronics》2005,48(5):398-404
In this paper, we study characteristics of detection of spatial signals from an antenna array in the case of short samples.
All the studied decision statistics are obtained on the basis of the generalized likelihood ratio for arbitrary-size samples.
As an example, we develop the working characteristics for detecting a useful signal representing one or two coherent plane
waves against the background of spatially uniform and nonuniform noise. The efficiency of the used statistics is compared
with the χ2 criterion for detecting noise-like signals.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 5, pp. 446–453, May 2005. 相似文献
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Tim Huege 《Brazilian Journal of Physics》2014,44(5):520-529
Nearly 50 years ago, the first radio signals from cosmic ray air showers were detected. After many successful studies, however, research ceased not even 10 years later. Only a decade ago, the field was revived with the application of powerful digital signal processing techniques. Since then, the detection technique has matured, and we are now in a phase of transition from small-scale experiments accessing energies below 10 18 eV to experiments with a reach for energies beyond 10 19 eV. We have demonstrated that air shower radio signals carry information on both the energy and the mass of the primary particle, and current experiments are in the process of quantifying the precision with which this information can be accessed. All of this rests on solid understanding of the radio emission processes which can be interpreted as a coherent superposition of geomagnetic emission, Askaryan charge-excess radiation, and Cherenkov-like coherence effects arising in the density gradient of the atmosphere. In this article, I highlight the “state of the art” of radio detection of cosmic rays and briefly discuss its perspectives for the next few years. 相似文献
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介绍了基于核四极矩技术的爆炸物检测原理及信号处理方法.系统分析了NQR信号检测中主要误差来源,提出多种方法消除NQR信号处理中检测误差,主要包括相关累加消除随机噪声;单通道自适应消除振铃影响;相关性检测抑制同频干扰.实验表明相关检测可有效提高NQR信号信噪比,提高微弱NQR信号检测的准确性. 相似文献
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电磁波检测技术的应用,可以防止对人体的辐射。当今无线通讯技术迅猛发展,如何对变电所及输电线与移动电话基地台所产生的电磁场强度进行评估,便成为一个重要的工作。通过分析电磁波特征,提出了对这些电磁波辐射设施所产生的电磁场强度检测的方法。 相似文献
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Jinwei Jia Limin Liu Yuying Liang Zhuangzhi Han Xuetian Wang 《Entropy (Basel, Switzerland)》2022,24(11)
Radio frequency (RF) stealth anti-sorting technology can improve the battlefield survival rate of radar and is one of the research hotspots in the radar field. In this study, the signal design principle of anti-sequential difference histogram (SDIF) sorting was explored for the main sorting algorithm of the SDIF. Furthermore, we designed a piecewise linear chaotic system with interval number parameterization based on random disturbance and proposed a method to modulate the repetition period of widely spaced signal pulses using a chaotic system. Then, considering the difficulty of the traditional signal processing method to measure the velocity of the highly random anti-sorting signals designed in this paper, we used compressed sensing (CS) technology to process the echoes of the signals to solve the velocity and distance of the detection targets. Finally, simulation verification was performed from the correctness of the signal design principle, the performance of the chaotic system, the anti-sorting performance of the designed signals and the recovery and reconstruction performance of the signals by CS. The results show that: (a) the signal design principle presented in this paper can guide the signal design correctly; (b) the performance of the piecewise linear chaotic system with interval number parameterization is better than that of the classical one-dimensional chaotic system; (c) the anti-sorting signal modulated by the chaotic system can achieve anti-SDIF sorting, and the anti-sorting signals designed in this paper can be processed to obtain the velocity and distance of the targets. 相似文献
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介绍了一种基质辅助激光解吸电离的进样方法-气溶胶进样方法.包含基质和分析物的气溶胶粒子在大气压力下直接进入气溶胶飞行时间质谱仪,粒子产生的散射光信号由光电倍增管收集,通过外部的时序电路,给出气溶胶粒子粒径的信息并触发266 nm Nd:YAG激光器,可以同时获得气溶胶粒子的粒径和基质辅助激光解吸电离质谱与其他的液体进样方式相比,它可以实现单粒子进样,因而样品消耗较少.主要研究了基质与分析物的摩尔比和激光能量对分析物离子信号的影响,合适的摩尔比和激光能量分别为50-110:1和200-400μJ. 相似文献
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Experiments which show coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays are designed for a detailed study of the development of the electromagnetic part of air showers. Radio detectors can operate with 100 % up time as, e.g., surface detectors based on water-Cherenkov tanks. They are being developed for ground-based experiments (e.g., the Pierre Auger Observatory) as another type of air-shower detector in addition to fluorescence detectors, which operate with only ~10 % of duty on dark nights. The radio signals from air showers are caused by coherent emission from geomagnetic radiation and charge-excess processes. The self-triggers in radio detectors currently in use often generate a dense stream of data, which is analyzed afterwards. Huge amounts of registered data require significant manpower for off-line analysis. Improvement of trigger efficiency is a relevant factor. The wavelet trigger, which investigates on-line the power of radio signals (~V2/R), is promising; however, it requires some improvements with respect to current designs. In this work, Morlet wavelets with various scaling factors were used for an analysis of real data from the Auger Engineering Radio Array and for optimization of the utilization of the resources in an FPGA. The wavelet analysis showed that the power of events is concentrated mostly in a limited range of the frequency spectrum (consistent with a range imposed by the input analog band-pass filter). However, we found several events with suspicious spectral characteristics, where the signal power is spread over the full band-width sampled by a 200 MHz digitizer with significant contribution of very high and very low frequencies. These events may not originate from cosmic ray showers but could be the result of human contamination. The engine of the wavelet analysis can be implemented in the modern powerful FPGAs and can remove suspicious events on-line to reduce the trigger rate. 相似文献
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We calculate beam patterns (BPs) and power characteristics of radio telescopes in the multibeam regime with the use of different types of microstrip focal arrays. A terrace design of focal array for illumination of the asymmetric secondary mirror of the RATAN-600 radio telescope and a symmetric paraboloid dish is proposed. Ways for optimization of this type of array are considered. Characteristics of a radio telescope with a millimeter-wave planar circularly polarized focal array are calculated. Some applications of multibeam microstrip focal arrays are considered.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,Vol.48, No. 2, pp. 95–109, February 2005 相似文献
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