Performance and Method of Despread-spectrum in a Matched-filter

The archtecture and characteristic of digital matched filter circuit used for PN code synchronization are introduced and the method of PN code serial search acquition based on DMF has been researched in AWGN channel.Furthermore the detection probability and false alarm probability are derived for different correlation time(partitive period or whole period).Finally,the results of calculation and emulation are given in order to be employed as useful theoretical bases for reserching the acquisition performance of digital matched filter.     

Application of Wavelet & Multi-Resolution Analysis to Detection of the Time of PN Code Acquisition

In the field of CDMA system, DS-SS technology has been used widely. Thereby, a great deal research on acquisition method of PN code is based on DS-SS. In the traditional way, the power detection method of judgment is used widely. Based on the characteristic of PN code acquired signal (namely BPSK signal or QPSK signal) and characteristic of un acquired signal (namely white Gaussian noise), this paper introduces the wavelet detection method of PN code acquisition time. Meanwhile, the performance of wavelet threshold is also studied. In the end, the statistics of parameters in this detection method is made. The result indicates that the wavelet & multi resolution has practical value in the signal processing.     

A blind adaptive reduced-rank receiver for ultra-wideband communication systems

A low-complexity blind adaptive receiver for ultra-wideband (UWB) systems in the presence of both multiple access interference (MAI) and inter symbol interference (ISI) is proposed, which is composed of two stages. In the first stage, a reduced-rank algorithm based on the multi-stage Wiener filter (MSWF) is considered to suppress the MAI and extract multi-path components. Channel estimation using the projection approximation subspace tracking with deflation (PASTd) algorithm and multi-path combining are then performed to further enhance the signal to interference plus noise ratio (SINR) of the desired user in the second stage. The simulation results show that the proposed receiver exhibits reasonably good bit error ratio (BER) performance compared with those of matched filter, conventional Rake receiver, decorrelating Rake receiver and adaptive receiver based on constant modulus algorithm (CMA). Moreover, it has faster convergence speed and less complexity.     

Image Secure Communication Based on Logistic Map

The chaotic sequences generated by logistic map are used as the carrier, and the image secure communication scheme is proposed based on that the sequences possess a good correlation property. Promising results are obtained on Lenna image by computer simulation. The obtained results indicate that the transmitted source image can be correctly recovered and the proposed scheme is reliable when transmitter and receiver using identical initial value even under the situations of a noisy channel. However, the tiny difference of initial value between transmitter and receiver will result in failure to communication. Finally, the quality of recovered source image is assessed, and the approximate formula of bit-error rate in term of code length is also obtained.     

Study and Design on S5933 Special Chip Data Acquisition System Based on PCI Bus

The paper explains the data transfer mechanism based on the PASS-THRU channel of S5933, and gives a method to develop data acquisition system based on PCI bus, the problem of designing the PCI interface controller is avoided, saving time and cost of development production. The use of CPLD makes the stucture of the system more integrated. The 32-bit data acquisition system,the speed of data transmission is faster,the CPU resource and PCI bus resource are spared.     

Novel channel estimation algorithm for OFDM/TDM over fast fading channels

For the shortage of tracking ability against fast fading channel of the existing pilot structures and channel estimation algorithms in OFDM combined with time division multiplexing (OFDM/TDM) system, an improved channel estimation algorithm is proposed. The channel transfer functions are obtained by estimating the channel properties with two adjacent time domain multiplexing (TDM) pilot sequences, while the channel state information of the OFDM/TDM symbols is obtained with interpolation Combined with frequency domain equalization based on minimum mean square error (MMSE-FDE), the proposed algorithm can significantly compensate the path loss over fast fading channels. Simulation results show that, compared with the existing channel estimation algorithms, the proposed algorithm can achieve better performance, which is not only capable of dealing with slow fading channels, but also has a better tracking ability against fast fading channels with the same data transmission efficiency.     

A Data Detector Based on Channel Equalizer Designed for the Downlink of CDMA Systems

In code-division multiple-access (CDMA) systems,sub-optimum multi-user or joint detection algorithms have been studied recently, which are mostly designed for the uplink situation. The algorithms are too complex to implement for the downlink situation. The conventional receiver consisting of matched filters is often inefficient in eliminating MAI. The authors propose a data detection algorithm designed for downlink of CDMA systems which introduce channel equalization to eliminate MAI. It consists of a channel equalizer and code matched filter. The equalization algorithm is based on zero forcing (ZF) criterion.The performance of the algorithm is better than metched filter's and its complexity is cower than tunt of sub-optimum multi-user detection.     

Development of Data Acquisition and Processing System Based on DSP and USB 2.0

The data acquisition and processing system are proceeding towards faster, more powerful, easier to use and more cost effectiveness. This paper discuss the design of the high speed and convenient data acquisition and processing system based on DSP and USB 2.0, and expatiates the principle and method of the virtual instruments system in detail. The system employs an ADS8346 to sample the six channel signals simultaneously with a resolution of 16-bit.It utilizes EZ-USB FX2 as the USB2.0 interface, which can achieve the high speed communication between the host and the system. It uses TMS320VC33 (dsp) as the core chip, which can accomplish the function of the main control and real-time digital signal processing. The system enhances the virtual instruments' advantage more by the combination between software and hardware.     

嵌入式Linux系统在粮库中的应用

近年来，随着嵌入式计算机技术的飞速发展，嵌入式系统得到了越来越广泛的应用，尤其是在工控、仿真、数据采集等领域。嵌入式系统需要嵌入式操作系统作支持，而由于Linux操作系统结构清晰，源代码开放性等方面的优势，在嵌入式系统中也得到了广泛的应用。本文以中央储备粮赤壁直属库管理监控系统的设计为背景，论述了基于Linux的嵌入式工作站取代传统的工控机为主的现地控制单元在粮库管理监控系统中的应用过程以及基于Linux的嵌入式工作站的设计。     

Multi-Step Iterative MUD Technology for TD-SCDMA System

Joint Detection technology is a hot point in the research of TD-SCDMA system. Because of a SNR degradation, JD can not reach the need of system performance when system loads is close to the spread factor. MSJD and iterative multi-user detection are put forth to overcome the problem. When iterative MUD is adopted, the research shows that system performance is close to single user performance after 3 iterations, but its computational complexity grows exponentially with the number of code channel. When MSJD is adopted, complexity is reduced compared with iterative MUD, but system performance of code channels numbered K is only close to system performance of code channels numbered K/2 as JD is used. Considering computational complexity and system performance, multi-step iterative multi-user detection technology is brought forth based on iterative MUD and MSJD. According to simulation, the result can be concluded that complexity is reduced compared with single iterative MUD and system performance is improved compared with single MSJD.     

Improved CMI code in passive induction setting system 〖JP〗

Aiming at the low energy transmission efficiency of the passive induction setting system with the existing codes, an improved CMI code is proposed as baseband code by changing the equivalent average time of high level during a code cycle under 2ASK modulation. The properties are analyzed, such as energy transmission efficiency, power spectrum and the error probability in incoherent demodulation in AWGN channel. The code is successfully applied to passive induction setting system, and the decoding method and measured voltage waveform are given. With the code, the energy transfer efficiency is improved by 60% than that of CMI code. It is not only beneficial to energy transmission, but also has the merit of CMI code that the bit timing information is extracted easily, which is fully utilized in incoherent demodulation to solve the sampling moment error accumulation problem resulted from the instability of internal oscillator.     

Design of nondestructive test system for plasma clots

One of the most important measures that are used to guarantee blood transfusion safety is to detect clots in the plasma before transfusion. To overcome the disadvantages of manual detection method, this research designs a nondestructive testing (NDT) system for plasma clots inspection based on machine vision technique and artificial neural networks. The key technology for system design are studied and presented. Image acquisition is performed by custom-designed software based on MATLAB platform, and the methods of image cut, reverse color, median filter as well as gray cutting are adopted to preprocess image. The use of fisher discrimination method, combined with iterative threshold segmentation method and the selection of connected domain, can successfully eliminate the interference of air bubble and correctly extract the image of plasma clots. Plasma clots are discriminated by a recognition model based on artificial neural network BP algorithms. The results of clinical contrast experiment shows that the system can effectively detect whether plasma contains plasma clots and the new system shows a much higher degree of repeatability and stability. From the image acquisition and processing to the recognition of plasma clots, the detecting time of a sample is no more than 1 min.     

High Speed Multi-channel Data Acquisition System and Storage System Based on PCI Bus

The paper first introduces principium and the developing actuality of data acquisition system about ICT.The authors then discuss PCI protocol and structure,function and work principle of the PCI bus controller S5933.Base on these,with the circuit design tools such as MAX+PLUSII,PROTEL 99SE and VHDL,etc.,the two types of high speed multi-channel data acquisition system based on PCI bus have been designed by using PASS-THRU channel and FIFO channel of S5933.     

Status Quo and Expectation of Human-machine Interaction in HCR

Human-centered idea and human-machine collaboration are emphasized in the Human Centered Robotics, which is mainly used for human-machine cooperation required mission in dynamic and non-structural environment. This paper presents a WearComp based interface that gets over the space and time limitation on human-robot interaction. By adapting AR(augment reality) in outputting channel, the information of robotics status and warning was accentuated in the transmission. That method effectively saves the resources of transmission band and reappearance, lightens the burden of operators and contributes to a good operator consciousness to local condition and remote environment. By parallel and mutual compensation of MultiModality interaction, and by integrating and fusing the redundant information, the ambiguity and noise of inputting information can be eliminated. All of above get rid of input bottleneck; a more efficient and humanistic human machine interaction is provided.     

Association analysis for detecting significant single nucleotide polymorphisms for phosphorus-deficiency tolerance at the seedling stage in soybean [Glycine max (L) Merr.]

Tolerance to low-phosphorus soil is a desirable trait in soybean cultivars. Previous quantitative trait locus (QTL) studies for phosphorus-deficiency tolerance were mainly derived from bi-parental segregating populations and few reports from natural population. The objective of this study was to detect QTLs that regulate phosphorus-deficiency tolerance in soybean using association mapping approach. Phosphorus-deficiency tolerance was evaluated according to five traits (plant shoot height, shoot dry weight, phosphorus concentration, phosphorus acquisition efficiency and use efficiency) comprising a conditional phenotype at the seedling stage. Association mapping of the conditional phenotype detected 19 SNPs including 13 SNPs that were significantly associated with the five traits across two years. A novel cluster of SNPs, including three SNPs that consistently showed significant effects over two years, that associated with more than one trait was detected on chromosome 3. All favorable alleles, which were determined based on the mean of conditional phenotypic values of each trait over the two years, could be pyramided into one cultivar through parental cross combination. The best three cross combinations were predicted with the aim of simultaneously improving phosphorus acquisition efficiency and use efficiency. These results will provide a thorough understanding of the genetic basis of phosphorus deficiency tolerance in soybean.     

Channel estimation for MB OFDM UWB system based on tap detecting

A novel channel estimation algorithm is proposed for MB OFDM Ultra Wide Band systems based on tap detecting by exploiting the sparse property of channel impulse response. The channel parameters are estimated using the DFT algorithm based on cyclic convolution property of the receive signals. The nonzero taps are detected by exploiting the matching pursuit(MP) algorithm. The new estimated channel parameters are obtained by forcing the zero taps to zeros. Simulation results demonstrate that it has better MSE (mean square error) performance for the four channels proposed by IEEE. Especially for CM1 and CM2 channels, the performance of the algorithm has been greatly improved.     

Multiple Turbo Codes for Satellite Communications

Satellite communication channel has the characteristic of power limited, band abundance, and powerful error correcting ability FEC scheme is needed. For its near Shannon limit error correcting capability, Turbo codes may be suitable for satellite communication systems. The multiple Turbo codes can utilize channel capacity sufficiency and overcome the disadvantages of power limited for satellite communication systems. Force on the needed for satellite communication systems, multiple Turbo codes is adopted and server decoding schemes were proposed with simulation. Simulation results show that, the schemes proposed can get near channel capacity error correcting performance with short code block.     

Development of Measurement and Control System of Engine Test-bed Experiment for Motorcycle

Engine test-bed experiments are the main means of engine performance test, whose necessary developing trend is to apply measurement and monitoring system based on the computer. This paper introduces alteration for engine test-bed experiment system. By adopting data acquisition system, using web and ftp technique, computer-controlling and remote monitoring in real-time are realized. And the details of singlechip are mainly discussed based on data acquisition system, testing-software, web and ftp technique. The improved system realizes automation of engine test-bed experiment and data processing. It can save time and manpower, increase the productivity and improve the working condition. Especially the interface of system software developed by Delphi under Windows is simple, clear and easily dealt. The practical application proves that the new system has good value for engineering.     

Improved DMT systems with multiple time domain equalization

DFT(discrete fourier transform)based discrete multi tone (DMT) transceivers have achieved great success in high speed data transmission. When the cyclic prefix is no shorter than the channel impulse response (CIR), the DMT system is ISI (inter symbol interference) free. For the channels with very long CIR, such as DSL loops, time domain equalizer (TEQ) is typically added at the receiver to shorten the impulse response and improve performance. This paper proposes a filter banks approach to design the TEQ to maximize the bit rate. A DMT system is introduced with a pair of complex conjugating TEQs. For the design and implementation costs, the scheme shows the best performance price ratio.     

Real-time Infrared Image Acquisitionand Processing System Based on PCI Bus

In the system of infrared imaging acquisition, it is necessary to improve data transfer to satisfy the characteristics of high speed and real time. So,this paper introduces PCI bus and PCI inerface to imaging acquisition. The protocol of data transfer of PCI local bus and the structure of PCI9050 are studied in detail, and the IRFPA data acquisition system are described based on the protocol of data transfer of PCI local bus. The system adopts frame buffer to make slow transmission between peripheral circuit and PCI bus.CPLD is also used as a master of logic time control?