Entity

Time filter

Source Type


Fan D.,Shandong University of Science and Technology | Fan D.,Shandong Provincial Key Laboratory of Robotics and Intelligent Technology | Lv C.,Shandong University of Science and Technology | Cao M.,Shandong University of Science and Technology
Advanced Materials Research | Year: 2011

Gabor transform is very suitable for time-frequency analysis and good for filtering non-stationary signals. The threshold of the Gabor transform filter is a key factor for the filter's effectiveness. A novel threshold based on initial highest inter-cluster distance probability (IH-ICDP) is described in this paper and it can make the filter more efficient. Some experiments have been carried out under several conditions to evaluate the new threshold's characteristics. The experimental results show that Gabor transform filter with this proposed threshold works better than wavelet transform filter, especially when the signal's SNR is very low. From the evaluation results, it is possible to consider that the threshold presented is optimal or nearly optimal. Source


Fan D.,Shandong University of Science and Technology | Fan D.,Shandong Provincial Key Laboratory of Robotics and Intelligent Technology | Liang H.,Shandong University of Science and Technology | Cao M.,Shandong University of Science and Technology
Sensors and Transducers | Year: 2014

The amplitude difference of the sediment layer’s echoes is always so large that the acoustic time difference becomes much difficult to get correctly. The existing methods of time varying enhancement for the multipath signal like ultrasonic echo have some limits in de-noising or practical application. This paper employs the second Iterative Passive Time Reversal Mirror to accomplish time varying enhancement for the ultrasonic signal. According the principle of measuring the sediment thickness in borehole by ultrasonic, the paper has established the system model to describe the processing of ultrasonic transmitting through the mud-sediment media, and simplified the channel in a linear, space-invariant, time-invariant multipath channel with two paths. Based on the model, the process of enhancing echoes of sediment layer by 2nd Iterative Passive Time Reversal Mirror is presented. Using the echoes of sediment with different thickness obtained in lab circumstance, two typical experiments to enhance the echoes have been taken. From the two experiments’ results we can see, 2ndIterative Passive Time Reversal Mirror is sure to give the later arrival echo bigger gain than to the earlier one, thus reduce the amplitude difference of the two echoes. © 2014 IFSA Publishing, S. L. Source


Fan D.,Shandong University of Science and Technology | Fan D.,Shandong Provincial Key Laboratory of Robotics and Intelligent Technology | Gao Y.,Shandong University of Science and Technology | Cai Q.G.,Shandong University of Science and Technology
Applied Mechanics and Materials | Year: 2013

The ultrasonic technique is a new method for detecting the borehole sediment thickness and has been gradually developed in recent years. However, there are still several key technologies needing to be further studied and developed. This paper focuses on studying and designing the ultrasonic processing circuits including the mono-stable flip-flop circuit, the driving circuit, the amplification filtering circuit and the automatic gain control circuit. Under the environment of Multisim 10.0, the designed circuits are simulated. The results show that the deigned ultrasonic driving circuit has a strong driving capacity and is capable of completely meeting the bandwidth requirements in measuring the sediment thickness by ultrasonic. The automatic gain control circuit is capable of strengthening the ultrasonic signal in a time varying mode so that the output signal can be kept stable within the given range. So it has a significant effect on the ultrasonic measurement of sediment; the designed amplification, filter bandwidth and the quality value can all meet the system requirements. Meanwhile, the integrated filter is adopted and few peripheral components are used, therefore, the system design is greatly simplified. © (2013) Trans Tech Publications, Switzerland. Source


Fan D.,Shandong University of Science and Technology | Fan D.,Shandong Provincial Key Laboratory of Robotics and Intelligent Technology | Gao Y.,Shandong University of Science and Technology | Zhao Y.,Shandong University of Science and Technology
Applied Mechanics and Materials | Year: 2013

As the key junction between the ground and underground, hoisting systems as well as mines themselves are of vital importance to coalmine production. Laser ranging method is studied as a new solution of getting the real-time position directly. Furthermore, multi-scale phase-based laser ranging principles are utilized in the system. The paper is aimed to conduct research into the problems existing in standard signal generating while using laser to locating the hoisting container, and to design standard sine generator circuits with DDS technology and DDS devices AD9850 to generate multiple frequency standard signals. In view of the serious noise disturbance in high frequency output, 4-order Chebyshev low-pass filter is designed, by using the integrated analog filters LT 6600-15, to filter the sine signals from AD9850 and to effectively weaken the noise disturbance. The established practical circuits are tested, obtaining trillion level high frequency and low frequency sine signals and fulfilling the requirements for the location system of hoisting containers. © (2013) Trans Tech Publications, Switzerland. Source


Fan D.,Shandong University of Science and Technology | Fan D.,Shandong Provincial Key Laboratory of Robotics and Intelligent Technology | Lan A.,Shandong University of Science and Technology | Liang H.,Shandong University of Science and Technology | Cao M.,Shandong University of Science and Technology
Information Technology Journal | Year: 2013

Time Varying Enhancement (TVE) is an important technology to deal with multipath fading often encountered in communication and measurement using electromagnetic wave, sound or laser. The self-focusing function of Time Reversal Mirror (TRM) makes it effective in blind TVE by realizing the thought of TVE automatically. Iterative Passive TRM (IPTRM) further strengths its TVE competence by using iterations. This study illustrated and analyzed the principle of TVE of IPTRM for the multipath signal in mathematics, presented the formulas of Gain Ratio and its times in 2nd IPTRM and also simulated and discussed the characteristics of IPTRM in both TVE and noise-removing. Based on the characteristics, study further pointed out the optimal selection of interesting part in IPTRM result and the method to select optimized original gain ratio, so that to get more remarkable TVE without any decreasing the SNR promotion. Contrasted to the present ways of TVE, IPTRM in this study is more simplified and practicable by realizing blind TVE and de-noising at the same time. It is much better that the TVE's performance can be controlled by simply changing the original gain ratio in estimated channel. © 2013 Asian Network for Scientific Information. Source

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