TITLE:
Frequency Structures Vibration Identified by an Adaptative Filtering Techiques Applied on GPS L1 Signal
AUTHORS:
Ana Paula C. Larocca, Ricardo E. Schaal, Gabriel do N. Guimarães, Igor Machado da Silveira, Paulo César Lima Segantine
KEYWORDS:
L1 GPS Frequency Processing; Filtering Techniques; Millimetric Displacements; Single Frequency Receiver
JOURNAL NAME:
Positioning,
Vol.4 No.2,
May
21,
2013
ABSTRACT:
This paper
is part of a research under enhancement since 2001, in which the main
objective is to measure small dynamic displacements by analysis of L1 GPS
carrier frequency with 1575.42 MHz—wavelength 19.05 cm, under an
adaptive method for collecting data and filtering techniques. This method,
named Phase Residual Method (PRM) is based on the frequency domain analysis of
the phase residuals resulted from the L1 double difference static data
processing of two satellites in almost orthogonal elevation angle. In this work
it is proposed to obtain the phase residuals directly from the raw phase
observable collected in a short baseline during a limited time span, in lieu of
obtaining the residual data file from regular GPS processing programs. In order
to improve the ability to detect millimetric displacements, two filtering
techniques are introduced. The first one is the autocorrelation that reduces
the phase noise with random time behavior. The other one is the running mean to
separate low frequency from the high frequency phase sources. Two trials are
presented to verify the proposed method and filtering techniques applied. One
simulates a 2.5
millimeter vertical GPS antenna displacement and the
second using the data collected during a bridge dynamic load test. The results
show a good consistency to detect millimetric oscillations from L1 frequency
and filtering techniques.