共查询到18条相似文献,搜索用时 156 毫秒
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针对多样化攻击对终端设备嵌入式系统安全造成的严重威胁,设计一种嵌入式系统固件安全验证方法。基于固件安全分析和可信根完整性度量,提出基于Hash算法嵌入式系统固件安全验证方法,在验证计算机上设计安全验证软件,通过通信协议分析、串口侦听,实现固件二进制数据提取、安全固件Hash值建立、未知安全固件Hash建立等功能,完成嵌入式系统固件载入或者升级过程的完整性验证,并设计基于MD5算法的PLC固件验证软件进行对比实验。实验结果表明:该方法可以正确判断PLC系统固件完整性,可推广应用到其他具有固件的嵌入式系统设备中。 相似文献
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高性能和小型化是水声设备的重要发展趋势,研究嵌入式Linux平台在水声设备中的应用十分有意义。TI公司开发的OMAPLl37芯片采用独特的DSP与ARM相结合的双核结构,具有集成度高、硬件稳定性强、速度快、开放性好等特点。研制了基于OMAPLl37平台的数字信号处理分机系统,并对复相关测频算法在该平台上的实现方法进行了研究。具体包括该算法的原理分析,嵌入式Linux交叉编译平台的搭建、内核的编译下载、基于ARM与DSP双核操作系统的通信方式以及算法的硬件实现方法等,最后进行了电联调实验,实验结果达到了预期的效果。对于嵌入式Linux平台在水声设备中应用有一定的参考价值。 相似文献
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基于车体振动的特点提出一种应用于车载设备的三维隔振系统,建立了该系统的半主动模糊最优控制模型,并通过实验验证了该多维隔振系统的性能。该系统通过使用磁流变(MR)阻尼器与弹簧组成的隔振子系统代替3-RPC(旋转副-平移副-螺旋副)并联机构中的驱动器实现空间三维振动隔离。控制模型结合了H∞状态反馈控制方法和MR阻尼器的工作原理得到阻尼器的可输出控制力,并通过模糊模型计算得到MR阻尼器的输入电流。设计制造了一套振动隔离实验平台,并采用正弦信号和随机信号进行振动实验完成了对平台的隔振性能的验证。通过测量上平台的振动加速度表明此隔振系统具有良好的隔振效果。 相似文献
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多普勒测速仪是水面或水下平台速度测量的主要设备。提出了利用随机样本一致(Random Sample Consensus,RANSAC)算法来估计多普勒频移,从而使速度测量具有更高的稳定性。多普勒测速仪信号处理的核心是测量多普勒频移,该方法利用回波复相关相位是多普勒频移的一次函数来估计多普勒频移,进而计算得到平台速度,在估计频移时采用RANSAC算法以提高测频精度。为了验证方法有效性,对信号形式为连续波(Continuous Wave,CW)脉冲对的情形进行了仿真。结果表明,提出方法的稳定性得到明显提高。 相似文献
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《高技术通讯》2020,(1)
针对大部分基于深度学习的方法在一些计算力低的嵌入式设备中难以保证速度和精度上同时满足实际需求的问题,本文提出了一种面向嵌入式设备的基于深度学习的快速人群计数算法。本文首先设计了弱计算力平台加速网络(LPANet),结合单阶段目标检测算法对图像中出现的人体头肩区域进行快速检测,然后引入快速多目标跟踪算法对连续多帧的检测结果进行轨迹关联,进而进行准确的人群计数。本文建立了完备的头肩数据集对算法进行验证,算法以640×480的分辨率在ARM平台(双核cortex-A72)上获得20帧/s的运行速度和1.15的计数平均绝对误差精度。基于深度学习的头肩检测结合跟踪的人群计数算法为嵌入式设备在多种场景下的应用提供了可行方案。 相似文献
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针对深海海底探测中MultiPing(Multiple Pings)技术的回波识别问题,研究了编码多Ping发射与回波识别技术.信号编码使用2DPSK相位调制方式,以ADSP-CM403F混合信号处理器为核心设计MultiPing编码信号的DSP发射系统;回波解码使用差分相干解调法,用Gardner内插同步算法进行位同步,并基于Matlab中可视化的simulink平台搭建回波解码仿真模型,在示波器中显示回波信号到达的准确时间和解调出的码元序列,根据码元一致性确定每一列编码信号的传播时间,从而得到需要的海底信息;设计实验使用ADSP-CM403F在实验水池中发射75kHz中心频率编码信号,并在接收回波信号中加入不同信噪比的高斯白噪声模拟深海回波信号进行解码研究,得出不同判决门限下,误码率与信噪比的关系.通过对编码MultiPing技术的研究,验证了该方法的可行性. 相似文献
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富钴结壳作为一种重要的海底矿产资源,在工业生产中有着重要应用,具有潜在的开采价值,富钴结壳的厚度是评估开采矿区资源量的重要指标。论文基于原位参量探测器测量富钴结壳厚度,探测器向结壳垂直发射调制信号,并接收返回的原频、差频双通道回波信号,分别提取两个回波信号的包络,然后提取回波信号峰值点的到达时刻,采用时延差法测量结壳厚度。回波到达时刻的提取是影响测厚精度的关键因素,传统的包络提取方法如希尔伯特变换,可以准确地提取出原频信号的包络,但对差频信号的提取精度较差。因此,通过希尔伯特变换与自相关算法分别提取原频信号与差频信号包络,提高了测厚的精度。通过水池试验分析了该算法的测厚性能,随后将该算法应用于中国大洋某航次的富钴结壳海试数据,验证了该算法的可行性。 相似文献
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Dash P.K. Jena R.K. Panda G. Routray A. 《IEEE transactions on instrumentation and measurement》2000,49(4):746-753
The design of an extended complex Kalman filter for the measurement of power system frequency has been presented in this paper. The design principles and the validity of the model have been outlined. A complex model has been developed to track a distorted signal that belongs to a power system. The model inherently takes care of the frequency measurement along with the amplitude and phase of the signals. The theory has been applied to standard test signals representing the worst-case measurement and network conditions in a typical power system. The proposed algorithm is suitable for real-time applications where the measurement noise and other disturbances are high. The complex quantities can be conveniently handled using a floating point processor. Comparison of the results of the proposed method with those obtained from a real extended Kalman filter reveals the superior performance of the former method 相似文献
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Bucci G. Landi C. Ocera G. 《IEEE transactions on instrumentation and measurement》2000,49(5):1009-1017
The paper discusses a novel technique for testing Minimum Shift Keying (MSK) impulsive radio-frequency (RF) signal transmitters. This technique utilizes the acquired samples of a single shot signal to determine the trajectories of the frequency and phase, by means of a time domain analysis. The theoretical foundation of this technique is given, discussing the application to a pulsed RF MSK signal modulated with a bit-rate of 5 Mb/s, having a total duration of 6 μs and whose central frequency falls in the band going from 960 to 1206 MHz. The performance of the measurement algorithm (robustness, influence of the digitizer resolution, time base jitter, and noise on the precision of the measurement) has been evaluated by means of simulation tests. The method has been experimentally verified for the characterization of identification friend or foe (IFF) time division multiple access (TDMA) actual devices 相似文献
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A 24-GHz FMCW radar system is presented using a fractional-N phase-locked loop ramp generator. This fractional-N ramp generator achieves relative ramp nonlinearities below 10/sup -8/. Among others linear frequency ramps are important tools in high precision FMCW radar systems. Highly linear frequency ramps make post measurement error correction feasible. Other important aspects of the high performance FMCW radar system are the design of the microwave circuit and the digital signal processing of the IF signals. Furthermore, a large RF bandwidth of more than 3 GHz obtained by thorough simulations results in a high range resolution and a good potential measurement accuracy. To maintain this high potential accuracy, a phase slope algorithm is used to calculate the precise range value leading to a significantly better precision with absolute range errors below 0.8 mm, compared to the commonly used spectral center algorithm. 相似文献
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为了解决传统白光干涉测量技术中对线性位移机构的位移精度要求过高的问题,本文提出了一种全视场外差白光干涉测量技术。该技术主要通过使用存在差频的白光干涉信号作为光源来实现在大扫描步长和低扫描精度条件下相干峰位置的高精度检测。本文首先建立了白光外差干涉的数学模型,再根据数学模型提供的光强信号特性提出了整体系统设计方案,然后对测量方案的可行性进行了实验验证。最后针对多种误差对算法计算精度的影响进行了理论分析和数据对比。误差分析的结果表明:白光外差干涉测量技术提供更高的测量精度和更好的抗干扰性能,有效地降低了传统白光干涉测量对线性位移机构精度的严苛依赖,为光学自由曲面检测技术提供了更多的可选解决方案。 相似文献
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Routray A. Pradhan A.K. Rao K.P. 《IEEE transactions on instrumentation and measurement》2002,51(3):469-479
A simple and novel approach in the design of an extended Kalman filter (EKF) for the measurement of power system frequency has been presented in this paper. The design principles and the validity of the model have been outlined. The performance of this filter has been compared with some of the existing methods for estimating the frequency of a signal under noisy conditions. The feasibility of the proposed filter has been tested in the laboratory under worst-case measurement and network conditions, which might occur in a typical power system. Also, the proof of the stability for the proposed filter has been discussed for a single sinusoid. It has been found that the proposed algorithm is suitable for real-time applications especially when the frequency changes are abrupt and the signal is corrupted with noise and other disturbances due to harmonics 相似文献