Yu Changjun

Widely Linear Quaternion Unscented Kalman Filter for Quaternion-Valued Feedforward Neural Network

Recently, the quaternion-valued feedforward neural network (QFNN) has been developed to process three dimensional (3-D) and 4-D signals in quaternion domain, and the weight matrices and bias vectors of the QFNN were obtained based on the quaternion backward propagation (QBP) method. However, it should be noted that the QBP is a first-order quaternion gradient descent algorithm. The convergence speed of the QBP is usually slow and may not be very suitable to process nonstationary quaternion-valued signals. To address this problem, a widely linear quaternion unscented Kalman filter (WLQUKF) algorithm is proposed to train the QFNN. This is derived by utilizing some recent studies in the augmented quaternion statistics and the

Sound guidance vehicle based on AT89S52

\mathbb {HR}

Track initiation in Monostatic-Bistatic Composite High Frequency Surface Wave Radar Network based on NFE model

-calculus. With the augmented quaternion statistics, the WLQUKF is able to process general quaternion-valued noncircular, nonlinear, and nonstationary signals, effectively. Simulations on both benchmark circular and noncircular quaternion-valued signals, and on real-world quaternion-valued signals support the analysis.

Estimating of RCS of Ionosphere for High Frequency Surface Wave Radar

This system centers on high-performance microcontroller AT89S52. Through the motor control on ASSP chip MMC-1 which controlling two DC motors, it can achieve accuracy position control of the moving acoustic. The buzzer can make an aural signal on a certain frequency using the microcontroller AT89S52. Because the distances between the three audio receivers and the moving acoustic are different, the signal they receive has a certain time difference. Then the control system makes a control signal according to the time difference. This signal is transmitted to the moving sound source through a wireless transceiver module and guides its motion.

The characteristic analysis and improvement based on group delay measurement of Frequency-Translating Devices by using double-frequency phase difference method

Though a Monostatic-Bistatic Composite High Frequency Surface Wave Radar Network (MBC-HFSWR Network) is established to cover the shortage of the monostatic radar, how to judge the real target update from the plausible measurements to initiate tracks quickly and accurately still remains a challenging problem. A novel method utilizing unconventional characteristics for track initiation is proposed in this paper, which uses more accurate information and avoids the problem of low detection precision of high frequency radar. A highly intelligent information fusion model which is a combination of Neural network, Fuzzy reasoning and Expert system (NFE model) is presented to solve the problem above and the validity of the provided method is demonstrated by Monte Carlo simulations.

Simultaneous Altitude and RCS Estimation with Propagation Attenuation in Bistatic HFSWR

High Frequency Surface Wave Radar (HFSWR) has been shown to provide enhanced performance in over the horizon detection of targets and sea states remote sensing by the returns of targets and ocean surface. Meanwhile, HFSWR can also receive ionospheric echoes reflected by the ionosphere, which severely affect the radar detection performance. In this paper, the radar cross section (RCS) of ionosphere for HFSWR is estimated, which would help quantify the impact of the ionosphere to radar system and the performance of clutter mitigation techniques. Simulations are provided to illustrate the effect of parameters including radar operating frequency, scale size of irregularities, aspect angle and detection range on the RCS of ionosphere.

Method and its optimization for group delay measurement of Frequency-Translating Devices by using double-frequency phase difference method

Double-frequency phase difference method is a simple and effective means for measuring the group delay of Frequency-Translating Devices (FTD). Especially for measuring the group delay of FTD which cannot accept the other local oscillator, the method shows the irreplaceable advantage. In order to obtain an accurate description of the group delay characteristics in the pass band of FTD, two improved methods are put forward in this paper which are variable aperture measurement method and multiple-frequency phase difference(MFPD) method on the basis of the measuring group delay by using double-frequency phase difference(DFPD) method. The variable aperture measurement method uses genetic algorithm (GA) to optimize the measurement aperture and the measurement interval on the basis of the rate of the group delay, and the measured data is handled with the cubic spline interpolation and Taylor series expansion method. Finally, an accurate group delay characteristics curve of the system is fitted. The MFPD method turns the double-frequency into the multiple-frequency on the basis of the DFPD method, which improves the testing efficiency and the measurement accuracy in a great extent. However, the premise is that the measured output spectrum should have enough signal-to-noise ratio. The simulation results show that these two improved methods are equally effective in reducing the measurement error and improving the measurement accuracy greatly.

A Knowledge Engineering Method for Track Initiation in Complex Conditions

High frequency surface wave radar (HFSWR) is traditionally unable to detect target altitude information. To simultaneously estimate the target altitude and radar cross-sections (RCS) with bistatic HFSWR, a novel estimation model is proposed with the variation of the propagation attenuation, and the target echoes are utilized to construct the measurement equation. The presented model is completely observable to the target state, which can contribute to preferable estimation results. In order to improve the estimation accuracy, a centralized fusion model is adopted to fuse four measurement vectors. Simulations and practical examples demonstrate the effectiveness of the proposed estimation model.

Bi-station OTH radar locating and tracking using only range and Doppler measurements

Group delay is a key parameter describing the phase characteristic of the signal transmission system, which can also measure the phase linearity of the continuous signal passing through transmission system. The group delay of Frequency-Translating Devices (FTD) is measured by the double-frequency phase difference method in this paper. But the measurement error will increase in the FTD whose group delay changes greatly. In view of this problem, an optimization method is put forward. Combined with polynomial fitting of high order, this proposed method, which uses the reasonable selection of the parameters such as measuring aperture and measurement interval, can improve the measurement precision and the test efficiency.

Method and apparatus for detecting and tracking faint target of high frequency ground wave radar

In a complex environment radar plot is often changing dramatically, non-uniform, discontinuous, uncertain and containing lots of false alarms. It is difficult for tracking system to form tracks in such complex environment. Traditional track formation methods can not accurately determine the size of track initiation gate and select specific initiation criteria. In this paper, an intelligent information processing method is proposed to solve track initiation in complex environments. The track initiation is considered as a progress of plot identification, classification and fuzzy information processing. According to the integration and fusion of neural network (NN), fuzzy reasoning (FR) and expert system (ES) technology, an intellectualized track initiation knowledge reasoning system is constructed which can realize structural, functional, algorithmic and hierarchical complementation. Further more the adaptive robust learning algorithm and the weighted synthesis reasoning algorithm are used in this system. Real data experiment shows that the proposed knowledge engineering method can effectively solve track initiation problem in complex conditions.