Applied Mechanics and Materials Vols. 519-520

Abstract: In this paper, A new on-line LLR optimization method based on the generalized mutual information (GMI) maximization is proposed for LDPC coded BICM systems. As the BP decoder is sensitive to imperfect soft demodulator output information, it is necessary to correct the LLRs to provide the reliable information for BP decoder. The proposed method searched the scalar factors to maximize the GMI for each bit channel, and applied them to the demodulator output LLRs. Different from the previous reference, the proposed found the factors by on-line computation with minor complexity. This characteristic makes it is more effective in the real systems where the channel changes rapidly. Numerical and simulation results verify that the proposed method achieves noticeable performance improvement for MIMO-BICM systems with LDPC codes.

Abstract: Although Non-continuous OFDM (NC-OFDM) has the unique advantage of eliminating interference to authorized user in cognitive radio context, it also confronts a difficulty of reducing peak to average power ratio (PAPR) like other OFDM techniques. In this paper, carrier interferometry is proposed to apply in NC-OFDM system in order to reduce its PAPR using the construction feature of CI code itself. The coding principle of CI code is analyzed at first. Then NC-OFDM base-band system based on carrier interferometry (CI/NC-OFDM) is modeled. Theoretical analysis and matlab simulation results indicate that CI code can bring 3 dB lower PAPR reference with the same probability of exceeding some PAPR reference, compared with traditional NC-OFDM system. This method is effective and feasible and gets better BER performance as well.

Abstract: This paper studied separation algorithms for Seismic signals with time dependence. A covariance-based procedure was adopted to compute the polarization angle in crosswell seismic data, accomplishing the separation of reflecting P wave and conversion SV wave. Numerical experiments show that the width of sliding windows should be 1.5 apparent period of seismogram. The results of experiments illustrate the procedure is effective.

Abstract: An novel decoupled estimation algorithm based on kalman filter is presented to solve the line-of-sight (LOS) rate estimation problem in terminal guidance of air-to-air combat. The measurements of target azimuth and elevation are obtained by missile-borne active radar seeker which use a monopulse doppler radar. As it cant be directly measured by this kind of radar, the LOS rate which is needed as the input of guidance law should be estimated from these angle measurements. The close-loop simulation of LOS rate estimation in typical terminal guidance scenario that an air-to-air missile seeks a military fighter validates the presented algorithm.

Abstract: This paper makes some improvements on Roberts representation for straight line in space and proposes a coarse-to-fine three-dimensional (3D) Randomized Hough Transform (RHT) for the detection of dim targets. Using range, bearing and elevation information of the received echoes, 3D RHT can detect constant velocity target in space. In addition, this paper applies a coarse-to-fine strategy to the 3D RHT, which aims to solve both the computational and memory complexity problems. The validity of the coarse-to-fine 3D RHT is verified by simulations. In comparison with the 2D case, which only uses the range-bearing information, the coarse-to-fine 3D RHT has a better practical value in dim target detection.

Abstract: The accuracy of radar measurement is an available data source to ads-b measure. Track fusion can make the aircraft track is more accurate, it is more significance to the accuracy of radar measurement. Through the establishment of ads-b and radar measurement equation, the algorithm is put forward, and verified the simulation and confirmed the feasibility of the algorithm.

Abstract: This paper analyzed a blind source separation algorithm based on cyclic frequency of complex signals. Under the blind source separation model, we firstly gave several useful assumptions. Then we discussed the derivation of the BSS algorithm, including the complex signals and the normalization situation. Later, we analyzed the complex WCW-CS algorithm, which was compared with NGA, NEASI and NGA-CS algorithms. Simulation results show that the complex WCW-CS algorithm has the best convergence and separation performance. It can also effectively separate mixed image signals, whose performance was better than NGA algorithm.

Abstract: Based on wavelet threshold de-noising method which put forward by Donoho, we analyze and compare the advantages and disadvantages of hard threshold, soft threshold and some improved threshold methods. Based on polynomial interpolation method, a new threshold function is proposed, which is continuous in the whole threshold area, with little constant deviation between the estimated wavelet coefficients and original signal wavelet coefficient, and high-order derivative and easy processing. The simulation results show that this method can give better optical effect, SNR gains and MSE performance.

Abstract: The measurement noise variance in the process of EKF is prone to bring error accumulation and can lead to filter divergence. Aiming at this kind of shortcoming, in this paper we build model of target motion observed on a single measurement point in a two-dimensional plane firstly. Secondly, we compare two methods, the variance estimation based on the signal-to-noise separation of wavelet transform and EKF algorithm based on noise variance estimation, applying in target tracking. Then, we adopt the wavelet transform to distinguish noise from the measurement signal real-timely. And the median variance estimator is used to estimate the measurement noise, which can improve the precision in EKF of target tracking by combining with EKF. Finally, the method of Monte Carlo simulation is used to prove its effectiveness and practicality.

Abstract: A no op amp structure full CMOS reference voltage circuit is designed. The two currents which are proportional to absolute temperature (PTAT) and complementary to absolute temperature (CTAT) are added together to get the reference output voltage which is obtained through a resistance. The characteristics of the new circuit are simulated using 0.5 μm BSIM3V3 spice models in HSPICE. The simulation results show that the output voltage of the circuit is 997mV, the power consumption is 1.12mW, the temperature coefficient is 15.2 ppm/°C in the range from-30°C to 100°C at the supply voltage of 2V.