A Novel Ground Based Multi Bistatic Radar for Interferometric Measument of Displacement Vector -...
Transcript of A Novel Ground Based Multi Bistatic Radar for Interferometric Measument of Displacement Vector -...
Filippo Parrini
Technologies for Environmental and Cultural Heritage Laboratory (TECHLab)Department of Electronics and Telecommunications
University of Firenze (Italy)
Ground based radar interferometry
Ground based radar interferometry
LINE OF SIGHTDISPLACEMENT
Multi-bistatic radar: operating principle
Three independent interferometric measurements:
•TX1 - RX (monostatic)•TX2 - RX (bistatic)•TX3 - RX (bistatic)
Multi bistatic radar: operating principle
d: target displacement d1,d2,d3: target displacement projections
Multi bistatic radar: issues
Instrumental issues Geometric issuesRadar issues
Cable thermal drift Multi-bistatic RCSof natural/artificial
targets
Measurement geometry
determination
Displacement componentsestimation
Instrumental issues: cable’s thermal drift
Highly phase stable cable
This effect has not been compensated yet
Radar issues: bistatic RCS
Natural or man-made reflectors usually havea very low RCS in multi bistatic mode
It is more difficult to have radar reflectorswith a good RCS in several directions
in order to perform a robust interferometric analysis
Geometric issues
2) The targets position in the reference system has to be determined (it can be retrieve from radar range measurement)
3) Target displacement vector (dx, dy, dz) has to be estimated(made with the following relation)
A measurement setup geometrywhich assure a small condition number for matrix A
is necessary for a good accuracy in displacement vector estimation
1) The multi-bistatic radar position in the reference system has to be known(it can be easily measured with additional instruments)
(d1,d2,d3) interferometric measurements
Experimental tests in controlled environment
No vertical baselinewas achieved
Experimental tests
Special multi-bistatic targetautomatically positioned and rotated
Side view Front view
Experimental test #1: displacement along y axis
Direction of the displacement during the 1st test
Displacement of target measured by three radar channels (d1,d2,d3)
Experimental test #1: displacement along y axis
Measurement displacement along the reference system axis(X = red, Y= blue)
Errors:
Mean: -0.01 mm
σ: 0.03 mm
Experimental test #1: displacement along y axis
Experimental test #2: displacement along any direction
Direction of the displacement during the 2st test (β=23.5)
Experimental test #2: displacement along any direction
Errors:
Mean: -0.02 mm
σ: 0.03 mm
Conclusions
The novel sensor was tested in a controlled environment showing good performances in term of measurement accuracy.
A novel multi-bistatic radar sensorhas now been designed and set up in order to provide three dimensional measurement capabilities.
Only LOS component of displacement is provided by traditional interferometric radar.
Measurement of displacement vector is of paramount importance in static and dynamic tests on civil structures.