Based on the fiber optical grating sensing principle and the sensing model of axial stress function on fiber optical grating,two factors which caused the Fiber Bragg Grating axial sensitivity shift are analyzed-elastic foundation effect and wave-guide effect caused by the fiber diameter change,and the changing curves were drew.

Study progress of multipath effect in structural health monitoring based on GPS

The radar interference equation which is used usually is not accurate because of not considering multipath effect.

In order to give assistance to how to use the chaff in various tactical situations,this paper analyzes the influence of the multipath effect on chaff centroid jamming on the basic of introduces the principle of the low altitude target s multipath effect.

In this paper,we introduce the cause of unstable tracking at low-elevation and analyze the fact that surface reflected wave entering antenna mainly causes multi-path effect.

This paper adopts adaptive digital beam forming(ADBF) method to reduce the influence of multi-path effects when the phased array radar detects the small skimming targets.

The results show that the developed antenna choke ring can effectively reduce the multi-path effects and can improve the interference-resistant ability of the .

In this article the multi-path effects model of wireless data link between two aircrafts is established with the field effects analysis method according to the general multi-path effects model based on mirror reflection.

According to the characteristics for the shipboard radar detecting and tracking flying targets in low altitude or super-low altitude, the following models for detecting targets, emission signal , multi-path effects and sea clutter are set up.

This paper carries out a detailed analysis about antenna beam splitting caused by SSR multi-path effects,and it is of great significance for improving the accuracy of radar detection.

Vondrak bandpass filter,which has good signal resolution over its signal truncation frequency band and is effective in separating structural vibrations from global positioning system(GPS) multipath effects,was applied to GPS structural deformation monitoring.

A method based on the technique of cross-validation to automatically identify wavelet signal layers is developed for separating noise from signals in data series,and applied to mitigate GPS multipath effects.

The Vondrak filtering method based on the Helmert type variance component estimation(HVF) is presented and applied to the study on GPS multipath effects.