Wireless Sensor Network (WSN) technology has been applied more and more widely and node localization is an important aspect of it. Bounding Box localization algorithm has been used in many cases. The purpose of this paper is to study the localization accuracy of the three different strategies based on Bounding Box localization algorithm and to explore the influence of the two parameters, the number of the anchor nodes and communication radius, on the localization accuracy. Firstly, the paper illustrates the principals of three strategies according to whether the unknown nodes that have been located will participate in locating other unknown nodes or not. Then the simulation condition is set, and the average localization error is gotten using three strategies respectively. The result shows the localization accuracy of Strategy C is the highest. Finally, the paper studies the influence of the number of the anchor nodes and the length of the communication radius on the localization accuracy and gives the optimal number of anchor nodes and communication radius when used in practice.
For the high cost of practicality experiments and the low precision of available model data cause the deficiently of the effectiveness of the aeromagnetic detection result, a magnetic field simulation method of submarine aircraft model is proposed based on COMSOL Multiphysics finite element software. First, the submarine is equivalent to the hollow cylinder model, and the magnetic field distribution of the distance of 5 times the length of the submarine is received through the simulation. Then the aircraft geometrical model is established to analyze the mechanism of aircraft jamming magnetic field, and the four-way flight scheme of compensation flight state is proposed to get magnetic field simulation data. For the simulation difficulties of large-scale model in the detection flight state, a simulation method of model separation and data superposition is proposed to get the component and the total data of magnetic field. Finally, the aircraft interference magnetic field modeling and the use of ridge estimation method to compensate for compensation flight and detection flight magnetic field data. Four-course flight data compensation accuracy within 0.5nT and detection flight data after compensation can be distinguished the submarine signal. The correctness of the finite element simulation method and the magnetic field data is verified, which is of great significance to the study of aeromagnetic deection simulation.
Proc. SPIE. 9679, AOPC 2015: Optical Fiber Sensors and Applications
KEYWORDS: Fiber optic communications, Signal to noise ratio, Signal processing, Sensors, Array processing, Fiber optics sensors, Interference (communication), Data processing, Data conversion, Computer simulations
The single-channel blind source separation (SCBSS) technique makes great significance in many fields, such as optical fiber communication, sensor detection, image processing and so on. It is a wide range application to realize blind source separation (BSS) from a single optical fiber sensor received data. The performance of many BSS algorithms and signal process methods will be worsened with inaccurate source number estimation. Many excellent algorithms have been proposed to deal with the source number estimation in array signal process which consists of multiple sensors, but they can not be applied directly to the single sensor condition. This paper presents a source number estimation method dealing with the single optical fiber sensor received data. By delay process, this paper converts the single sensor received data to multi-dimension form. And the data covariance matrix is constructed. Then the estimation algorithms used in array signal processing can be utilized. The information theoretic criteria (ITC) based methods, presented by AIC and MDL, Gerschgorin’s disk estimation (GDE) are introduced to estimate the source number of the single optical fiber sensor’s received signal. To improve the performance of these estimation methods at low signal noise ratio (SNR), this paper make a smooth process to the data covariance matrix. By the smooth process, the fluctuation and uncertainty of the eigenvalues of the covariance matrix are reduced. Simulation results prove that ITC base methods can not estimate the source number effectively under colored noise. The GDE method, although gets a poor performance at low SNR, but it is able to accurately estimate the number of sources with colored noise. The experiments also show that the proposed method can be applied to estimate the source number of single sensor received data.
There are varies modulation formats such as ASK, OOK, BPSK, QPSK, DP-QPSK. The DP-QPSK modulation format appears as the best performing 50 Gbit/s modulation format solution with higher transmission efficiency and stronger anti-interference ability. Therefore, this topic has great significance for the study of a test system of DP-QPSK optical transmission. There is hardware and software design of the test system. Hardware design is the basis and prerequisite for the design of the test system, requiring further understanding of the composition of the test system. The software which completes the work of data processing is a crucial part of the whole test system.
Differential phase-shift keying (DPSK) has been widely implemented and developed in high-speed optical communication systems. The low error rate detection at high access rate is one of the considerable issues in practical engineering application. Balanced detection based on fiber Mach-Zehnder delay interferometer (MZDI) is the typical optical DPSK signal detecting method. It requires that the free spectrum range (FSR) of the MZDI equals the reciprocal of symbol period of the DPSK signal. For the reasons of ambient temperature variation and nonlinear phase noise, a dynamic frequency offset always exists between the FSR and the reciprocal of symbol period. That may introduce some optical signal-to-noise ratio (OSNR) costs and fault detections. Therefore, it is significant to inhibit the frequency offset on DPSK detection. In this paper, firstly, we discuss the effects of frequency offset on DPSK detection, and realize the conclusion that frequency offset is virtually equivalent to an additional phase difference between adjacent symbols. Secondly, through simulation, we analyze the feasibility of DPSK detection in the presence of a definite range of frequency offset, and present the quantitative computation of effective coverage, duty cycle, and optimal sampling time of symbol interference. Some issues which should be considered in practical implementation are also discussed. Finally, according to the relationship among phase difference, temperature and voltage, we propose a phase difference compensation scheme which can automatically adjust the voltage for optimal detections, and dynamically track the changing of ambient temperature and nonlinear phase noise. Furthermore, we ascertain the performance of the voltage requested for implementing the scheme. The scheme can be also developed to quadrature phase-shift keying (QPSK) and differential QPSK (DQPSK) modulation situations.
With the improvement of people’s living standard, the requirement of network is higher and higher. The rate and capacity of network communication are rising all the time, it ’s outstanding on the backbone networks. The rate of backbone network had improved from 10G to 100G in recent years. This change also put forward new requirement for optical network equipment . The key technologies of lower order cross-connect equipment is discussing in this passage. This passage mainly discusses the following aspects: time division multiplexing of STM-1 lower-order pointer interpretation and lower -order pointer generation. By using the technologies discussed in this passage, the lower -order cross-connect devices has the higher cross-connect capacity under consuming the same logic resource, and the equipment will meet the requirement of the backbone network transmission capacity.
In order to achieve the receiving task of 100Gbps Dual Polarization-Quadrature Phase Shift Keying (DP-QPSK) optical signal acquisition instrument, improve acquisition performance of the instrument, this paper has deeply researched DP-QPSK modulation principles, demodulation techniques and the key technologies of optical signal acquisition. The theories of DP-QPSK optical signal transmission are researched. The DP-QPSK optical signal transmission model is deduced. And the clock and data recovery in high-speed data acquisition and offset correction of multi-channel data are researched. By reasonable hardware circuit design and software system construction, the utilization of high performance Advanced Telecom Computing Architecture (ATCA), this paper proposes a 100Gbps DP-QPSK optical signal acquisition instrument which is based on ATCA. The implementations of key modules are presented by comparison and argumentation. According to the modularization idea, the instrument can be divided into eight modules. Each module performs the following functions. (1) DP-QPSK coherent detection demodulation module; (2) deceleration module; (3) FPGA (Field Programmable Gate Array); (4) storage module; (5) data transmission module; (6) clock module; (7) power module; (8) JTAG debugging, configuration module; What is more, this paper has put forward two solutions to test optical signal acquisition instrument performance. The first scenario is based on a standard STM-256 optical signal format and exploits the SignalTap of QuartusII software to monitor the optical signal data. Another scenario is to use a pseudo-random signal series to generate data, acquisition module acquires a certain amount of data signals, and then the signals are transferred to a computer by the Gigabit Ethernet to analyze. Two testing results show that the bit error rate of optical signal acquisition instrument is low. And the instrument fully meets the requirements of signal receiving system. At the same time this design has an important significance in practical applications.
In the era of information, the big data, which contains huge information, brings about some problems, such as high speed transmission, storage and real-time analysis and process. As the important media for data transmission, the Internet is the significant part for big data processing research. With the large-scale usage of the Internet, the data streaming of network is increasing rapidly. The speed level in the main fiber optic communication of the present has reached 40Gbps, even 100Gbps, therefore data on the optical backbone network shows some features of massive data. Generally, data services are provided via IP packets on the optical backbone network, which is constituted with SDH (Synchronous Digital Hierarchy). Hence this method that IP packets are directly mapped into SDH payload is named POS (Packet over SDH) technology. Aiming at the problems of real time process of high speed massive data, this paper designs a process system platform based on ATCA for 40Gbps POS signal data stream recognition and packet content capture, which employs the FPGA as the CPU. This platform offers pre-processing of clustering algorithms, service traffic identification and data mining for the following big data storage and analysis with high efficiency. Also, the operational procedure is proposed in this paper. Four channels of 10Gbps POS signal decomposed by the analysis module, which chooses FPGA as the kernel, are inputted to the flow classification module and the pattern matching component based on TCAM. Based on the properties of the length of payload and net flows, buffer management is added to the platform to keep the key flow information. According to data stream analysis, DPI (deep packet inspection) and flow balance distribute, the signal is transmitted to the backend machine through the giga Ethernet ports on back board. Practice shows that the proposed platform is superior to the traditional applications based on ASIC and NP.
In this paper, a novel single grating system is constructed to test the dynamic characteristics of FTRG (Friction Twister Roller Guider). There are only several simple optical components in this instrument. To acquire high precision result in optical displacement measuring, the signal quality of moire fringes must be kept reliable and constant. And several adaptive processing methods to enhance the signal quality are provided in this system. The process platform is based on SHARC (Super Harvard Architecture Computer) DSP and flash sample technique. At last, the result of the test is listed to show the effects of the optical system and the algorithms in digital signal processor. After combining the counting algorithm, subdivision algorithm and adaptive filters together, the qualities of the signals are highly enhanced. The typical test experiments on FTRG, which are demonstrated in this article, include Long displacement without vibration and Short displacement with axial vibration. Between the two experiments, the latter is more difficult to measure displacement during a vibrating environment. All the measure results are compared with other advanced instruments. It is still precise and reliable when some other instrument out of work in axial vibrating environment.
A kind of software solution is provided to implement counting and division of moire fringes in this paper. No complex electronic circuit of digital counter exists in the digital reader that adopts this software solution. The counting and division of the fringes are completed in DSP (digital signal processor), so it can solve the problems that counting circuit can't match the subdivision system properly by logical judgement. Because of utilizing high-speed optoelectronic convertor and flash sample technique, the system can process moire signal with wide frequency range. The example demonstrated in the paper can count and divide signals from DC to 1MHz, i.e., if the optical sensitivity of the signal is 1 fringe per micrometers , the fastest measure speed can reach 1000mm/s. The experimental result shows that the software solution has high accuracy and sound reliability.
Proc. SPIE. 4223, Instruments for Optics and Optoelectronic Inspection and Control
KEYWORDS: Signal processing, Digital signal processing, Moire patterns, Digital filtering, Electronic filtering, Optical signal processing, Filtering (signal processing), Optical amplifiers, Optoelectronics, Data acquisition
To acquire high precision of subdivision in optical displacement measuring, the signal quality of moire fringes must be kept reliable and constant. Several software solutions to enhance the signal quality of moire fringes are provided in this paper. The process platform is based on SHARC DSP and flash sample technique. Three methods of adaptive digital filter are used respectively to eliminate the unwanted drift of signal, improve the orthogonality of two channels of sine and cosine intensity signals of moire fringe, and keep the amplitude of the signal constant. Firstly, the operation procedure of the acquisition and process system is described, then the principle of the adaptive signal process is explained. And at the same time, the result of the experiment is also listed to show the effects of the process software in digital signal processor.
The basic principle and characteristics of displacement sensor with nonsymmetrical double gratings (DSNDG) are briefly described in the paper firstly. Besides the wide range and high resolution, very fine optical subdivision can be attained with the technique of DSNDG, which can largely expand the measurement range without decreasing the resolution. Then DSNDG is proved with the theories of Doppler effect. And the experimental research is done in the end. In the experimental research, some experimental phenomena are analyzed. The reasons and conditions for the formation of moire fringe are introduced. The effect of optical configuration, such as the angle of incidence and position of the two gratings, on the moire fringe is discussed. Then the factors affecting the moire fringe contrast and the methods to improve the fringe contrast are analyzed.
According to the characteristics of video sensor output, a method based on DSP (Digital Signal Processor) and VLSI (Very-Large Scale Integrated Circuit) memory is provided. Firstly, this paper introduces the signal characteristics of the video sensors, e.g. high-speed 2-D array charge coupled device and infrared image devices. Then the special requests are got to process and store video signals from the point of view of output speed and data capacity. In the sequence of the function modules of normal signal processing system, the pipeline cache, pre-process, smart trigger, dynamic storage, and permanence storage of signals or data are systematically explained. And to satisfy the need of video frequency process system, different devices and operation modes are determined for every module. Among these, the selection and performance request of DSP applied in video system, the characters of all kinds of memory, and the begotten problems when they are applied in the system are described in detail. Secondly, the interfaces that utilize video FIFO, great- capacity DRAM, and flash memory for permanence storage are emphasized. In the last design, the DMA (Direct Memory Access) page operation mode is presented in detail when DSP and flash memory are used. At the end of this paper, the methods by which the video signal process system communicates with computer are introduced.
This paper introduces the master-slave DRCP (Distributed Control Protocol), a new protocol for field bus. In this protocol, the master controller uses differential signals to transmit control command and to communicate with the executive units. It can control several executive units at the same time, and can also command each unit respectively. Because the protocol adopts bi-directional communication mode, the controller can obtain the feedback information and measure data from the executive units while it is sending commands. So the protocol has data acquisition ability. First, the reason and significance to bring forward this protocol is presented, then the physical link and the signals transmitted on data line is introduced, which is followed with an example based on RS485 standard. Secondly, the application situation and system configuration to utilize this protocol is described. In this part, the standard to select the operation speed of processor is given. Thirdly, the paper emphasizes on communication regulation. In the end, an applied example is given.