Influence of MUD on the System Capability of CDMA

In CDMA communication system, the relativities between users result in Multiple Access Interference (MAI). With the increase of users, MAI becomes the main jam of broadband CDMA communication system. Multi-User Detection (MUD) is the most important technology of anti-jamming in the broadband CDMA communication system, which can eliminates MAI effectively by using the information of all user signals to detection single. This paper analyze the expression of system capability without MUD and with MUD, and puts forward the way to increase system capability by using MUD. Then the influence of MUD on CDMA system capability is discussed by MATLAB emulation. Basing analysis and emulation, the conclusion is got: the higher the MUD efficiency, the better the improvement of CDMA system capability; under the same MUD efficiency, the lower data rate, the smaller inter-cell interference, the lower the ratio of bit energy to power spectrum, the better the improvement of CDMA system capability.     

Research on the improvement of the convergencespeed for CDMA system power control

Optimal power control with game-theory has been a hot research topic in code division multiple access (CDMA) system. However, the convergence speed of the power control algorithm based on traditional static game-theory is not fast enough and the power fluctuation is large during the iterative process. In order to solve this problem, dynamic game-theory is introduced into CDMA system power control algorithm. The simulation results show that the proposed algorithm, compared with the distributed power control algorithm based on the traditional static game theory, can improve the convergence speed obviously with the same power spending.     

Group based DBF MUD in CDMA mobile communication system

For the CDMA wireless cellular communication system, a new methodology is proposed to combine digital beamforming (DBF) with multi user detection (MUD) technology which harnesses the co channel interference mitigation and obtains better performance. The proposed approach assigns all the users within a cell into separated groups according to their direction of arrival (DOA). Then, only one DBF branch is employed for a singular group so that the main lobe is steered to the desired users in the group and nulls are directed to the mobile stations in other group. Furthermore, inter group interference is degraded by MUD following the DBF. The new strategy simplifies the weight vector calculation and solves the unorthogonal channel problem. Additionally, it decreases the bit error rate. The analysis and simulation illustrate the fruits of the new mechanism.     

Joint Parameters Estimation for CDMA Signals

In wireless communications,mobiles emit signals that arrive at a receiver with multiple paths,each with its own direction of arrival(DOA),path delay,fading,and Doppler shift frequency,which influence the quality of communication seriously.These parameters should be taken into account in array signal processing.Based on CDMA signal,a novel Space-Time approach is proposed to estimation the DOA,time delay,and the Doppler shift frequency.Because utilize special signal model about space-time-frequency of mobile communications.The proposed algorithm has simpler structure and high quality of division.The simulation results show the feasibility and effectiveness of the method.     

如何提高LYLDC-1A粮情测控系统的数据采集与传输性能

在广泛调查国内外微机测温系统应用情况的基础上 ,结合我国粮情检测的需要 ,完成了微机测温测湿数据采集与传输系统的研究 ,系统具备了快速、稳定、准确采集传输测温信息的功能 ,较好地解决了抗环境干扰、抗雷击等技术难题。     

Machine Vision Aided Testing System for Flatness Based on Equal Inclination Interference Theory

An approach is described on the automated tracking of interference circle fringe to get the flatness accurately based on the Equal Inclination Interference Theory (EIIT). The system,based on the theory of EIIT, can be applied to grasp the changing fringe information, which is white alternating with black through the CCD camera. Following the basic principle of fringes image centro-symmetric, we create some windows, process only the interference fringes information in the windows. According to the position of the processed interference fringe and the position of the last adjacent interference fringe in the windows, the interference fringe variation value N from the starting measured point is received, it implies the changed altitude value from the starting measurement point. This method allows us not only get the fringe information of the half-wavelength integer multiple but also denote those of the half-wavelength decimal multiple. The system is proved to be effective experimentally. It is useful in metrology department for the high-precision flatness standard unit.     

The study on EMI principle and suppression method of vehicle ignition system

Vehicle ignition system is the main electromagnetic interference source. Electromagnetic radiation produced by ignition system will produce the interference to electromagnetic environment around. It is necessary to study the electromagnetic interference (EMI) principle, noise paths and suppression method. We analyze the electromagnetic interference principle of ignition system, and harness trouble-shooting related to electromagnetic interference is also tested. Results show that the spark discharge between spark plug electrodes is the main interference source in ignition system. Then, the paths of conducted interference and the reason of radiated emission are discussed in detail. Finally, two kinds of power supply cord EMI filters are designed and implemented on the basis of analysis results. Experimental results indicate that the filter can reduce the noise of power-wire in broadband range. Simultaneously, the radiation emission performance from power wire is also reduced observably. The proposed mixing filter has been demonstrated in this paper to perform satisfactorily with excellent effectiveness in suppression of conducted EMI from 10 MHz to 110 MHz, and the object car can also pass the EMC standard tests.     

The optical isolation method of suppressing electromagnetic interference of automotive ignition system

Electromagnetic radiation, which is caused by the engine ignition system, is the most powerful electromagnetic interference (EMI) source in the vehicles, as well as the main reason of most electronic control unit (ECU) malfunction. In order to reduce interference from ignition noise on ECU, we use optical isolation technology to isolate electrical connections between the interference source and the control circuit. The formation mechanism of the ignition system EMI is analyzed. The possibility of suppressing ignition system EMI with optical isolation technology is discussed. Then, as a result we design an experimental platform of suppressing ignition system EMI. The experimental results show that the effect of suppressing ignition noise, in 20~100 MHz frequency band, is obvious after applying optical isolation circuit. It can address the issue of automotive EMC.     

Leaf Cell‐Wall Components as Influenced in the First Phase of Salt Stress in Three Maize (Zea mays L.) Hybrids Differing in Salt Resistance

The leaf cell wall (CW) chemical composition of three maize (Zea mays L.) hybrids (salt‐resistant SR 03 and SR 12, salt‐sensitive Pioneer 3906) was investigated in the first phase of salt stress (100 mm NaCl) compared with the control (1 mm NaCl) treatment to investigate whether changes in CW composition were responsible for shoot growth reduction. Salt treatment caused a strong inhibition in shoot growth with a concomitant increase in the ratio between CW dry mass (DM) and shoot fresh mass (FM) and a decrease in CW cellulose concentrations in all hybrids. NaCl caused a large increase in the concentrations of total and non‐methylated uronic acid (UA) in salt‐sensitive Pioneer 3906 and salt‐resistant SR 12. The onset of the accumulation of non‐methylated UA was delayed in SR 12, which indicates that this may be one reason for the better growth performance of this hybrid under salt stress compared with Pioneer 3906. It is concluded that a low accumulation of non‐methylated UA in leaf CW may, among other mechanisms, contribute to salt resistance in the first phase of salt stress.     

A Subchannel Allocation Policy of Multicarrier CDMA

To attain high rate data and high quality of service in wireless communication, a subchannel allocation policy combined with subcarriers and power allocation is proposed. In the proposed system, instead of identical power over the subcarriers in parallel, each user's DS waveform is transmitted over the subchannels that have large fading amplitude among all the subchannels. The powers of the subcarriers with small fading amplitude are allocated to the subcarriers with large ones. It can effectively suppress multiple-access interference while obtaining diversity gains. The allocation policy based on fading amplitudes has the advantages of low computation and good convergence compared with the policy proposed in other papers. Thus, it is suitable for engineering.     

Changes of Surface Potential and Phospholipid Composition of Winter Wheat Callus Cells Grown at 5 and 25 °C

Water stress was imposed by cessation of watering (CW) on bread wheats and, in some experiments two spelt wheats, during 9–17 days, starting at the 4–5 leaves stage. Main shoot foliar stages (MSS) were delayed by CW and the effect remained thereafter.
The presence of side tillers (intact or partly destroyed by heat or potassium iodide (KI) was not beneficial to main shoot foliar development after the end of CW. Emergence of tillers after the onset of CW was also delayed, but the effect was small if timing was expressed in MSS. Secondary tillers were the most sensitive to water shortage, their number, size and foliar stage were drastically reduced.
The two cultivars of spelt wheats were not less sensitive to CW than the bread wheat tested.     

PD Online Measurement of Transformers with Wide Frequency Band System and the Noise Eliminating Method by Cascaded IIR Lattice Notch Digital Filter

The frequency band of conventional partial discharge (PD) measurement systems is selected just within several ten kilohertz. With the development of computer and digital signal processing techniques, wide frequency band (WFB) measurement systems have been used to detect PD in electrical equipment for its higher sensitivity. Nevertheless, the WFB measurement systems are easy suffered from the interference of strong field electromagnetism noises. A set of PD online monitoring system with frequency band from 50 kHz to 1 megahertz used for transformer is developed, in which pre-processing device and cascaded 2nd order IIR lattice notch digital filter are mainly used to suppress periodic narrow-band interference. With analysis of field monitored signal at a 220 kV substation, it is shown that the monitoring system not only can detect and extract the discharge pulse signal effectively, but also has the powerful capability of suppressing interference.     

The Application of Narrowband Interference Suppression in Direct Sequence Spread Spectrum

In order to improve the system effect, it is necessary take the technique of digital signal process to suppress interference, because of the finite gain and the narrow-band interference in system of direct sequence spread spectrum. The authors design a new filter structure improving on tunable digital heterodyne adaptive notch filters. This filter can adaptively track the interference frequency and control the bandwidth and depth of notch, which has the excellent agility and utility. The experiment proves this method overcomes limitation of other interference suppressions, hardly weaken the system performances, enhances the stability of the filter system, and can quickly track the interference frequency.     

Application of Trap Filter of 50 Hz in Brainwave Data Acquisition System

It's always difficult in technology to eliminate power interference of 50 Hz in Brainwave Data Acquisition System .Though traditional ways to eliminate it can also gain some effects, they have drawbacks such as high cost and low currency at all time. The use of trap filter of 50 Hz may solve the question radically. Through the authors' repetitious experimentation, it is proved that trap filter of VCVS not only eliminate power interference of 50 Hz farthest but also have merits of simple circuit structure, convenient coupling and upper reliability. The authors offer collected brainwave in strong power interference environment. It may be seen that it is very clear and clean. Because power interference of (50 Hz) exists in almost all Data Acquisition System, this type of trap filter possesses better currency, it is expected to win extensive application in medical apparatus of measurement of other biological electricity signals and industrial observation and control system.     

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.     

Adaptation of quinoa (Chenopodium quinoa) to Northern European agriculture: studies on developmental pattern

The inheritance of resistance to clubroot, caused by Plasmodiophora brassicae in Brassica oleracea was studied in the F₁, F₂and backcross progenies of three crosses between resistant and susceptible doubled haploid lines. Fresh weights of affected (CW) and healthy (HRW) parts of the root system were measured and R = ln((HRW+0.5)/(CW+0.5)) was used as a measure of resistance. R was shown to have a normally distributed error term with a constant standard deviation over the entire scale. Analysis of means indicated the presence of two complementary resistance genes in one of the crosses. In the other two crosses analysis of means also indicated two-locus interactions, in these cases reducing the cumulative effects of loci homozygous for resistance or for susceptibility alleles. The numbers of segregating resistance genes in these two crosses could not be determined. The presence of epistatic interactions precluded analysis of variance; therefore in this case the measurements were not more informative than the symptom grades analyzed in a previous study.R showed a high rank correlation (-0.85) with symptom grades assigned to the same plants. The results of genetic analyses of R were generally in agreement with those obtained earlier using symptom grades. Symptom grades can therefore be regarded as a reliable measure of symptom development, despite their more subjective nature.     

‘三白’石榴再生体系的构建

为建立适用于遗传转化和育种研究的‘三白’石榴再生体系,以带芽茎段为外植体进行组织培养研究。结果表明,最佳初代培养基为MS+BA 2.0 mg/L+ IBA 0.2 mg/L+ PVP 2 g/L,成芽率达83.1%,成芽个数为4.9;最佳增殖培养基为B5+ BA 0.8 mg/L+ IBA 0.5 mg/L+ AgNO3 0.2 mg/L+ GA3 0.2 mg/L+椰汁100 ml/L+PVP 2 g/L,增殖系数达5.6;最佳生根培养基为B5+ IBA 1.0 mg/L+椰汁100 ml/L,生根率达95.6%,移栽成活率达87.3%,由此建立了‘三白’石榴的再生体系。     

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.     

基于广义谐振理论的输电线路中波无源干扰谐振频率预测

现有IEEE（institute of electrical and electronics engineers）标准,目前只能明确0.5~1.7 MHz有限频段的输电线路无源干扰谐振机理。为拓展输电线路无源干扰谐振的研究频率,引入广义谐振理论,提出了一种基于电磁场能量平衡的干扰谐振频率预测构想。将大尺度空间下输电线路铁塔阵列及天线等效为广义封闭系统,从而基于复坡印廷定理,推导了电磁开放系统广义谐振因子的表达式,求解得到的广义谐振因子零值点为无源干扰谐振频点。该方法由于避开了传统将铁塔等效为半波天线的局限,因此可以实现中波频段无源干扰谐振预测。采用IEEE标准算例进行验证,结果表明：1.7 MHz频率以下,基于广义谐振理论的无源干扰谐振频率预测值和缩比模型实测值最大误差不超过±0.169 MHz。     

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.