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Cumulative pulses detection with appropriate cumulative pulses number and threshold has the ability to improve the detection performance of the pulsed laser ranging system with GM-APD. In this paper, based on Poisson statistics and multi-pulses cumulative process, the cumulative detection probabilities and their influence factors are investigated. With the normalized probability distribution of each time bin, the theoretical model of the range accuracy and precision is established, and the factors limiting the range accuracy and precision are discussed. The results show that the cumulative pulses detection can produce higher target detection probability and lower false alarm probability. However, for a heavy noise level and extremely weak echo intensity, the false alarm suppression performance of the cumulative pulses detection deteriorates quickly. The range accuracy and precision is another important parameter evaluating the detection performance, the echo intensity and pulse width are main influence factors on the range accuracy and precision, and higher range accuracy and precision is acquired with stronger echo intensity and narrower echo pulse width, for 5-ns echo pulse width, when the echo intensity is larger than 10, the range accuracy and precision lower than 7.5 cm can be achieved. 相似文献
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目的为了解决传统物流行业机器人避障系统中存在的测距精度低、抗干扰性差等问题。方法提出一种基于DSP的温补与小波阈值滤噪的高精度超声测距系统,包括DSP最小系统、超声波传感器、LCD显示模块、温度补偿电路和报警电路等。超声波测距系统通过实时采集环境温度来修正声速值,采用小波阈值变换算法对回波信号进行处理,以提升回波信号的信噪比和起始点锐度。结果应用CCS4.2软件与DSP芯片进行调试、实验,实验表明在距离0~1200 mm内,系统的测量误差为±4 mm。结论采用小波阈值变换算法和温补电路,提高了传统物流机器人避障系统的测距精度。 相似文献
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宽带声学多普勒流速剖面仪,利用伪随机编码调制发射脉冲信号以及复相关算法计算各水层反射回波的多普勒频移,进而达到测速的目的。复相关算法中,在排除模糊速度干扰的情况下,测速精度与脉冲信号的长度存在正比的关系。而脉冲宽度越长,所用来调制发射脉冲信号的编码阶数也越高,随之带来的便是速度模糊的问题。在复相关测频算法的基础上,针对长编码脉冲信号出现的周期性测频模糊情况,利用短编码脉冲信号的测频结果作为判别标准,选取恰当的周期性频偏作为计算结果,既提高了测速精度,又解决了精度提高所带来的周期性速度模糊问题,并且在实际应用中,提高了低信噪比条件下的测速精度。 相似文献
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A theoretical framework of a modified EP (envelope peak) method is developed. In this method, a wideband echo signal from each A line (one echo sequence) is first filtered in parallel by a bank of narrow-bandpass filters using a split-spectrum processing. The attenuation is then estimated from the EPs of each filtered signal using a narrowband technique. The combination of the split-spectrum processing with the narrowband technique enables the accuracy of the attenuation estimation to be well controlled without the precise measurements of the spectral shape and parameters of the transmitted pulses. On the other hand, the precision of the estimation is still determined by the bandwidth of the original echo signal, and is not affected by the split-spectrum processing. As a result, the modified EP method improves the accuracy of the attenuation estimation while retaining the high precision of the original EP method. Results from phantom experiments supported the theoretical analysis. 相似文献
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Kim H Zagzebski JA Varghese T 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(5):1153-1159
A problem with video signal analysis for estimating frequency-dependent ultrasonic attenuation is that relative echogenicity versus depth curves are distorted when broadband pulses are used. In this correspondence, we present results that demonstrate improved accuracy of attenuation estimates computed from B-mode or envelope data derived after narrowband (1 MHz BW) filtering at different frequencies around the center frequency of the broadband echo signal. Based on the premise that transducer center frequencies are selected in part on penetration or imaging depth requirements, simulation and experimental results for a typical ultrasound imaging system show that narrowband video signal analysis for frequencies lower than or at the center frequency of the broadband pulse provide unbiased attenuation estimation over this depth. Filtered signals above the center frequency of the pulse yield accurate results only at shallow depths. 相似文献
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随着电子技术的发展,半导体开关元件的切换频率不断提高。为了检测开关元件在快速切换开关时产生的脉冲电压信号,本文讨论了窄脉冲信号检测的原理和方法,设计并实现了脉冲测量电路。该电路分别采用高速ADC和DDR2存储器进行波形采集和存储,并在FPGA中设计检测电路,通过信号同步触发的形式实现窄脉冲信号的实时检测。实验表明:系统能够有效捕获到脉宽为100纳秒级的信号,且具有较高的幅度精度以及良好的实时性。同时,预触发长度可以通过编程实现。 相似文献
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目前隧道衬砌空洞检测以人工敲击判断为主,检测过程中由于受到检测人员水平、注意力等主观因素影响,检测结果存在较大不确定性,因此有必要研制一种智能化的检测装置实现空洞自动识别。文章开展了衬砌空洞敲击回声智能识别算法研究,通过提取隧道衬砌冲击回波的梅尔倒谱系数(Mel Frequency Cepstral Coefficient, MFCC)作为特征,针对敲击回声脉冲信号长度不一的特点,提出了变帧长MFCC优化算法,并面向小样本条件,建立了支持向量机(Support Vector Machine, SVM)的识别模型。试验结果表明,该模型对衬砌空洞识别准确率可达89.9%。 相似文献
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基于啁啾脉冲的反射层析激光雷达成像 总被引:1,自引:0,他引:1
反射层析激光雷达成像具有系统简单及对湍流不敏感的优势,但普通脉冲发射信号难以兼顾远距离和高精度探测的要求.基于上述情况,本文提出了一种基于啁啾脉冲信号的反射层析激光雷达成像处理方法.该方法首先对啁啾脉冲回波进行相干压缩处理,通过对处理后信号的包络提取得到目标在各方向的反射层析投影数据,最后利用卷积反投影算法实现高分辨力的图像重构.仿真结果表明,在同一投影角度,利用该方法得到的包络与目标反射率投影相一致;在投影角度范围大于60°时能够得到目标的轮廓信息,角度范围越大,成像越精确.研究结果验证了该方法的有效性. 相似文献
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Benkhelifa M.A. Gindre M. Le Huerou J.-Y. Urbach W. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1994,41(5):579-587
Theoretical studies made in the early 1980's suggest that ultrasonic imaging using correlation technique can overcome some of the drawbacks of classical pulse echography. Indeed by transmitting a continuous coded signal and then compressing it into a short, high resolution pulse at the receiver the total signal to noise ratio (SNR) is improved. The target location is determined by cross correlation of the emitted and the received signal. The band compression allows, by increasing SNR, the retrieval of echo signals buried in the receiver noise. Thus in medical-type echography, where the signal attenuation at fixed depth is proportional to the frequency, the SNR improvement allows the use of higher frequency signals and leads to improved resolution. We report here the results of comparative experimental studies of simple echo B type images as obtained by the classical pulse echo and correlation techniques. Because the optimisation of the coded signal plays a crucial role in the performance of the correlation technique we will also present a comparative study of the performances of the most common codes (m-sequences and complementary series). In particular we shall emphasise the following points: the relative importance of the central lobe as compared to the side lobes of the correlation function, which is directly related to the dynamic of the imaging system, the width of the correlation peak which is directly related to the axial resolution of the system, the facility of the realisation. The merit of B-mode images obtained with the coded signals will be discussed showing that as far as signal modulation is used the best results are obtained with periodic m-sequences 相似文献
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基于匹配追踪的稀疏分解方法原理简单,在工程实际中应用广泛,但其计算量大,重构精度也不够理想。针对此问题,利用水下目标回波信号的块稀疏特性,提出了水下目标回波的块信号稀疏分解方法。首先基于水下目标回波和块稀疏信号的基本理论,结合回波信号仿真结果,分析了水下目标回波信号的块稀疏特性;然后,充分考虑回波信号本身的稀疏结构,利用信号分块和原子分块的思想,针对水下目标回波提出了块信号的稀疏分解和块匹配追踪重构算法,并从理论上对其计算复杂度进行了分析;最后,采用仿真实验的方式,与传统方法进行对比。结果表明,该方法大大减少了计算量,提高了重构精度。 相似文献
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S. Yu. Demochko 《Measurement Techniques》1993,36(9):982-986
A simple processing method is described for correcting dynamically distorted pulse signal waveforms with high accuracy. The processing widens the effective working passband of the means of measurement by factors ranging from two to three.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 19–21, September, 1993. 相似文献