Bocheng Zhu

Reduced-order H∞ filtering for navigation with carrier phase

A reduced-order H∞ filtering algorithm for navigation with carrier phase is presented. By taking advantage of decoupling between filtering states in a navigation solution, this algorithm reduces computational cost and is robust in colored noise. Furthermore, the estimation precision is also improved by taking ambiguities as nuisance states when the filtering process converges. Applications to kinetic simulations under different noise are presented to demonstrate robustness and efficiency of the algorithm.

Improved innovation-based adaptive Kalman filter for dual-frequency navigation using carrier phase

A new adaptive Kalman filtering algorithm for dual-frequency navigation using carrier phase is presented. This algorithm gives consideration to both robustness and sensitivity by combining the two main approaches of adaptive Kalman filtering based on innovation-based adaptive estimation (IAE) and fading filtering. Applicable to the navigation using carrier phase measurements typically, this algorithm can balance the weights of observations and predicted states preferably. Applications to both practical static data and kinetic simulations are presented to demonstrate the validity and efficiency of the algorithm.

Scattering characteristics of dielectric periodic structures based on Floquet mode analysis and hybrid finite element methods

The scattering characteristics of dielectric periodic structures are discusses based on Floquet modes analysis and hybrid finite element methods in the paper. Propagating and evanescent Floquet modes are analyzed theoretically. The hybrid finite element method is developed. Then the effects of structure parameters, dielectric material, incident angle and frequency on propagation directions and power of Floquet modes are studied through numerical simulations and analysis. Meaning conclusions are drawn. Thus, this paper is of both theoretical and practical interest for the design and analysis of DPSs.

Volume scattering of 3-D discrete scatterers by using UV multilevel partitioning method

A fast method-UV multilevel partitioning method (UV-MLP) is developed to solve volume scattering by 3-D random-distributed scatterers. In the method Foldy-lax equations with higher order spherical partial wave expansions are used for spherical scatterers. Then the fast method UV-MLP is presented to accelerate the solution, where three key points: multilevel partitioning, rank pre-determination and UV decomposition are introduced. Finally we demonstrate the technique to the electromagnetic scattering problem by a large number of random-distributed particles.

A new DS-CDMA code synchronization scheme

DS-CDMA is widely used in 3G communication systems, GPS, WLAN and some other fields that require robust resistance against narrow band interference, multi-path time spread or interception. One most challenging and important problem in DS-CDMA is code synchronization, which includes code acquisition and code track. When SNR of the received signal is low, the synchronization becomes not very reliable, which means the system will miss the correct phase of the received signal at a high probability. And therefore, more synchronization iteration is needed. If the PN code is very long, more iteration will become unaffordable because it elongates the synchronization time. In this paper, a non-coherent addition method is proposed to increase synchronization reliability. Another problem that hasnpsilat been discussed in previous literature is chip doppler. It will make the synchronization lose locked abnormally. In the paper, a PLL aid resample method is also proposed to solve this problem. LabVIEW simulation shows that above two methods are very effective.

Radiation Analysis of Dielectric Conical Conformal Log-Spiral Antennas

Radiation properties of conical log-spiral antennas (CLSA) conformal on dielectric cones are analyzed by using the hybrid finite element and boundary integral equation method (FE-BI) in the paper. Firstly the radiation patterns of CLSA conformal on different dielectric cones and the ordinary CLSA are compared at the same geometry parameters and frequency. Then the influence of the spiral wrap angle and cone angle on the radiation of dielectric conical antennas are discussed. A design of geometry parameters of the dielectric CLSA with best radiation performance are finally obtained based on numerical simulations under the given dielectric parameters.

Cycle slip processing based on wavelet reconstruction for single-frequency GPS signal in kinetic precise point positioning

A new method for correcting carrier phase cycle slips in single-frequency GPS signal is presented. In order to ensure real-time capability and accuracy, processing based on wavelet reconstruction is developed to restrain the influence of noise. Applied to kinetic precise point positioning, this method can detect cycle slips sensitively and make correction accurately by processing linear combination of phase and code signals. An application on practical data is also presented to prove the effectiveness of this algorithm and show the superiority to conventional method.