A Blind Adaptive Jamming Canceller Using Antenna Array for GPS Receiver

Traditional beamformers need to know the incident angle of the desired signal leading while its abili-ty to handle interference is limited.In this paper,the constrained steer vector of linearly constrained min-imum-variance(LCMV)beamformer is modified to make sidelobe null to direction of powerful jammer.Inaddition,the state-space concept is used to describe the anti-jammer filter,and Kalman filter algorithm isdeduced by building the observation model and measurement equation.The new method is more efficient oncomputation and more robust to survive environment with large scale variation in interference strength.Fi-nally,simulation results shows that the new approach can form the null with its depth in proportion to powerin direction of jammer,and has steady convergence process.The novel method can effectively improve thesignal-to-jammer-plus-noise power ratio(SJNR)of GPS signals to make the correlation peak easy to track.

GPS P码接收机本地信号发生器的FPGA实现

P码作为GPS军用伪码,具有结构复杂、周期长且码速率快的特点,这使得使用P码的软件接收机不仅定位精度高,且具有很强的抗干扰和反欺骗能力。能够实现任意卫星的任意时刻P码的产生,对于实现P码直接捕获和跟踪有很重要的意义。对于P码的产生原理和结构进行了分析,基于MATLAB设计了相应的P码发生算法并进行简单的算法仿真。之后针对FPGA硬件平台对P码发生器进行了相应的模块设计,包含寄存器模块、延时模块、周期控制模块和寄存器相位模块等。测试实验结果表明P码发生器可以基本无延迟地生成任意卫星、任意时刻的P码。

A New GPS System for Continuous Deformation Monitoring

This paper presents a multi-antenna GPS based system developed for local continuous deformation monitoring. Due to a large number of points that needs to be monitored, the standard approaches of using permanent GPS receiver arrays will cause high cost. It eventually becomes the limiting factor for large-scale use of GPS in these application areas. Multi-antenna GPS system allows a number of GPS antennas to be linked to one GPS receiver by a specially designed electronic component, i. e. the so-called GPS multi-antenna switch (GMS), The receiver takes data sequentially from each of the antennas attached to the receiver. A distinctive advantage of the approach is that one GPS receiver can be used to monitor more than one point. The cost per monitored point (i. e. the expenses of hardware) is therefore significantly reduced.

A Study on The Multi-Antenna Geometrical Depolarization Channel Modeling

The traditional geometrical depolarization model that single transmitter to single receiver provides a simple method of polarization channel modeling. It can obtain the geometrical depolarization effect of each path if known the antenna configuration, the polarization field radiation pattern and the spatial distribution of scatters. With the development of communication technology, information transmission spectrum is more and more scarce. The original model provides only a single channel polarization state, so the information will be limited that the polarization state carries in the polarization modulation. The research is so significance that how to carries polarization modulation information by using multi-antenna polarization state. However, the present study shows that have no depolarization effect model for multi-antenna systems. In this paper, we propose a multi-antenna geometrical depolarization model. On the basis of a single antenna to calculate the depolarization effect of the model, and through simulation to analysis the main factors that influence the depolarization effect. This article provides a multi-antenna geometrical depolarization channel modeling that can applied to large-scale array antenna, and to some extent increase the speed of information transmission.

Time-Frequency System Builds and Timing Strategy Research of VHF Band Antenna Array

VHF (Very High Frequency) band antenna array will receive analog signal from universe for storage after digital sampling and adding time scale, and then do the interference analysis of different sub-station digital signal. It requires the time-frequency system with high precision and low drifting. This paper explains a time-frequency system of VHF band antenna, which can produce standard 10 MHz signal and clock signal needed by sampler, to ensure that two computers which sampling data has the same system time and the storage data has the accurate time scale, the system includes time comparison programme based on the GPS network timing two different sampling control computers. Timing strategy uses a time comparison software which based on the Labview graphical programming platform. This software captures the system time of two computers to analyze and determine the time deviation when the two computers occurs time offset, and then grant the GPS time of NTP server to the two computers through local area network in this time deviation. Final results show that this method can automatically calibrate the system time of the computers in the LAN, Precision Can Reach 0.1 s Orless.

Efficient design of rotary traveling wave oscillator array via geometric programming

This paper presents an efficient method for globally optimizing and automating component sizing for rotary traveling wave oscillator arrays. The lumped equivalent model of transmission lines loaded by inverter pairs is evaluated and posynomial functions for oscillation frequency, power dissipation, phase noise, etc. are formulated using transmission line theory. The re- sulting design problem can be posed as a geometric programJning problem, which can be efficiently solved with a convex opti- mization solver. The proposed method can compute the global optima more efficiently than the traditional iterative scheme and various design problems can be solved with the same circuit model. The globally optimal trade-off curves between competing objectives are also computed to carry out robust designs and quickly explore the design space.