Addressing the current challenges of weak target azimuth detection and inadequate precision in frequency modulated continuous wave (FMCW) radar systems, this paper proposes a novel method for precise imaging based on a motion array using FMCW radar for accurate range and azimuth estimation. The approach involves the use of a millimeter-wave FMCW radar with a motion array to capture target angular information, leading to a substantial improvement in azimuth estimation resolution, particularly for munitions. Additionally, spatial Fourier transform array signal processing is employed to achieve two-dimensional precise imaging of radar targets, encompassing both range and azimuth dimensions. Experimental results validate the effectiveness of the proposed approach, showcasing an enhanced angular resolution of the millimeter-wave radar, reaching 2.6°. The method demonstrates favorable azimuth estimation outcomes in diverse scenarios, including those involving multiple and planar targets. Overall, the introduced technique significantly elevates the precise detection capability of automotive millimeter-wave radar systems.
Enhanced optical transmission of metallic nanohole arrays stimulated the blooming research efforts on plasmonics and
rich applications. Here we studied the dependence of enhanced optical absorption on geometric parameters by nanohole
arrays on gold films in infrared wavelength (8~12μm). An empirical modeling for enhanced optical absorption is
summarized (based on a great many of simulation data and deviation analysis, and its goodness-of-fit test and
significance test is acceptable), which takes consideration of not only single parameters but also interaction parameters of
geometries. Through t-test, the interaction parameters with high significance are chosen, which could give high optical
absorption, and the interaction of different parameters was evaluated via Analysis of Variance (ANOVA). Our study
represents a new guiding rule for uncooled infrared detector design.
KEYWORDS: Ranging, Signal processing, Signal to noise ratio, Modulation, Signal detection, Interference (communication), Optical correlators, Frequency modulation, Environmental sensing, Target detection
A kind of signal processing method of the correlation detection is presented for the radio ranging system combined pseudo-random code binary-phase modulation with linear frequency modulation. The autocorrelation function of the ranging system is deduced. Especially, the anti-noise performance of this method is analyzed and simulated. The simulation result is consonant with the calculation value. The results show that the correlation detection method for the ranging system has strong anti-noise capability.
KEYWORDS: Modulation, Phase shift keying, Signal processing, Feature extraction, Radar, Current controlled voltage source, Frequency modulation, Phase modulation, Frequency shift keying, Signal to noise ratio
Currently, mostly used method for Instantaneous Frequency (IF) feature extraction of radar signal is two-dimensional
graph, which is easy for people to distinguish, but not for machines. This article proposes a feature extraction algorithm
based on instantaneous frequency of radiation source. Using the statistical change difference of different IF signals, we
formulate the classification feature vectors describing the various types of signal pulse modulation laws, according which
we do some classification experiments. The experiments prove that instantaneous frequency characteristics of radiation
sources can characterize the change difference of different modulation signals and have some anti-noise performance. We
are sure that this method can be used in signal sorting, and can be realized in practice.
A model of photodetector was established, and the expression of the interference to the photodetector caused by sunlight
directly propagating into the detector was given. With integrals over area elements, the filling of the view field of the
photodetector by the ground was discussed in detail. The expression of the interference to the photodetector caused by
sunlight scattered by the ground was deduced. The research presented in this paper is a contribution to the application of
photodetectors.
With the development of semiconductor laser technology, laser proximity fuzes have been widely used in various kinds
of guided missiles and routine ammunitions. Combined with the current situation, the digital laser fuzes system based on
the FPGA has been proposed in this paper. Combined with the current situation, the system has been divided into
emitting module, receiving module and signal processing module, the three modules have been analyzed in details. In the
emitting module, the driven circuit based on the FPGA has been developed, the laser pulse with 20ns width and 10kHz
repetition frequency have been obtained. Meanwhile, the emitting optical system and receiving optical system have been
designed. In the receiving module, the receiving circuit with preamplifier and A/D sampling and convert circuit have
been developed. In the signal processing module, anti-interference methods were proposed which can find applications in
the laser proximity fuze research.
Ultrasonic inherent characteristic and underwater environment make underwater ultrasonic image have speckle noise, and image contrast is low. So need a method to reduce speckle noise and enhance image contrast at the same time. In certain applications, however, the removal of speckle and image enhancement may be two contradictory problem each other, so we difficult to gain an ideal image processing result. For this reason, considerations in characteristic of the
underwater ultrasonic image, this paper provides a new speckle reduction and image enhancement anisotropic diffusion method based on wavelet technology. An anisotropic diffusion model has been established based on wavelet transform. We analyze the characteristic of the model and discuss the model's mechanism of action for removing speckle and enhance image edge of the underwater ultrasonic image. A compare experiment for real underwater ultrasonic image has been done using the method and other traditional methods. The experimental result indicates that the method proposed have strong speckle reduction and enhancement image ability. The purpose of removing speckle noise and enhancing edge at same time has been reached.
With the development of semiconductor laser technology, laser proximity fuzes have been widely used in various kinds
of guided missiles and routine ammunitions. An approach to pulsed laser fuze based on pseudorandom code is presented
in this paper. Based on the principle of laser fuze using pseudorandom code, the system has been divided into emitting
module, receiving module, optical system and information processing module. The different modules have been
analyzed in details and principles for selecting the parameters of the modules are given. The testing shows that laser fuze
based on pseudorandom code has a better ability of detection and a higher resistance to interference. The theoretic
foundation is provided for scientifically designing pulsed laser fuze of pseudorandom code.
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