Research on High-Accuracy Programmable Timer Used in Acquiring UWB Signals

UWB signal digitization depends, to a large extent, on the accuracy of sampling time. A highaccuracy programmable timer is therefore the key to implementing UWB signal data acquisition. A high-accuracy programmable timer based on the principle of ramp generators is described in this paper. The counting range of the timer is up to 16 bits, the timing precision is 8 ps, and the equivalent sampling rate is up to 50G Hz. No other identical product has been reported so far. This timer was successfully used in the data acquisition system for geological radar signals developed by us.

Signal and Data Processing of Television Based on Multistatic Radar Systems

A television based multistatic radar system is described. The commercial television transmitter is used as the illuminator in the multistatic radar system. The reflected commercial television signals are measured by an array of sensors. A data processing scheme is developed that adapts to the poor signal processing ability. The innovation is focused on the construction of the observation space, which could reduce the non linearity error. The new method leads to better system stability than the traditional one. Monte Carlo simulation is utilized and compared with the traditional method.

A quantitative analysis method for GPR signals based on optimal biorthogonal wavelet

Due to the disturbances arising from the coherence of reflected waves and from echo noise,problems such as limitations,instability and poor accuracy exist with the current quantitative analysis methods.According to the intrinsic features of GPR signals and wavelet time–frequency analysis,an optimal wavelet basis named GPR3.3 wavelet is constructed via an improved biorthogonal wavelet construction method to quantitatively analyse the GPR signal.A new quantitative analysis method based on the biorthogonal wavelet(the QAGBW method)is proposed and applied in the analysis of analogue and measured signals.The results show that compared with the Bayesian frequency-domain blind deconvolution and with existing wavelet bases,the QAGBW method based on optimal wavelet can limit the disturbance from factors such as the coherence of reflected waves and echo noise,improve the quantitative analytical precision of the GPR signal,and match the minimum thickness for quantitative analysis with the vertical resolution of GPR detection.

Research on weak signal extraction and noise removal for GPR data based on principal component analysis

The ground penetrating radar （GPR） detection data is a wide band signal, always disturbed by some noise, such as ambient random noise and muhiple refleetion waves. The noise affects the target identification of underground medium seriously. A method based on principal component analysis （PCA） was proposed to ex- tract the target signal and remove the uncorrelated noise. According to the correlation of signal, the authors get the eigenvalues and corresponding eigenvectors by decomposing the covariance matrix of GPR data and make linear transformation for the GPR data to get the principal components （PCs）. The lower-order PCs stand h^r the strong correlated target signals of the raw data, and the higher-order ones present the uneorrelated noise. Thus the authors can extract the target signal and filter uncorrelated noise effectively by the PCA. This method was demonstrated on real ultra-wideband through-wall radar data and simulated GPR data. Both of the results show that the PCA method can effectively extract the GPR target signal and remove the uncorrelated noise.

地雷(四)

3.4 特种地雷 用于警戒、照明、构成火障、造成毒剂或放射性物质沾染地段或其他特种任务的地雷。有水雷、信号地雷、照明地雷、化学地雷、燃烧地雷等。 3.4.1 水雷 布设在近岸浅水海域(通常水深5m以内)或江河、湖泊中,用于迟滞或毁伤舰船、水陆两用车辆等水中兵器。由壳体、引信和装药等组成。受到目标碰撞或目标物理场作用(磁、声、水压场等)时即可爆炸,也可操纵起爆。能破坏目标水下部分,使之沉没或损伤。水雷具有设置隐蔽、作用突然、破坏力大等特点,在现代战争中得到广泛使用。现代水雷以非触发水雷为主。