A J Gasiewski remote sensing course notes lecture21

33 Pages·00.794 MB·English

by  A J Gasiewski

ECEN 5254
Remote Sensing Signals and Systems
Professor Albin J. Gasiewski
Lecture #21 – April 3, 2012
ECOT 246
303-492-9688 (O)
[email protected]
Classes: ECCS 1B14 TR 9:30-10:45 AM
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Administration
• HW4 solutions posted on D2L
• HW5 posted on D2L, due April 10
• Reading:
– RSSS slides
– Skolnik Chapters 10,11 (on D2L)
– Additional references on D2L
• Term Paper:
– ~10 pages + figures, references
– Slide presentations in standard conference format held
on Friday, May 4 at end of semester. Schedule to be
arranged.
– Term paper and slide presentation templates on D2L
• Final Exam: Saturday May 5, 7:30-10:00 PM
in ECCS 1B14
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Last Lecture
• Sampling, resolution, fringe washing
• Noise
• Aperture thinning
• Intensity correlation (Hanbury-Brown-
Twiss Experiment)
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Today’s Lecture
• Radar principles
• Radar cross section
• Doppler effect
• Correlation receiver
• Matched filter
• Ambiguity
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Radar Principles
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Received Power - Point Scatterer
P G ^ ^
σ(k ,k )
General bistatic T T ^
s i
R , k
~
T i
radar system:
^
G
R ,k
R
R s
P
R
Received power in steady state:
^ ^
σ(k ,k ) is bistatic
s i
radar scattering
cross section:
Depends on λ,
size, orientation,
and polarization
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Received Power - Point Scatterer
P G ^ ^
σ(-k ,k )
Monostatic T ^
i i
R , k
~
i
radar system:
P
R
Received power in steady state:
^ ^
σ(-k ,k ) is back-
i i
scattering cross
section:
Depends on λ, size,
orientation, and
P varies as R-4 , G2 : polarization
R
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Radar Cross Section
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Radar Cross Section
Typical RCS values for λ ~ 3 cm wavelength (X-band):
^ ^
σ(-k ,k )
i i
RCS increased by:
 sharp edges
 flat and normal surfaces
 high dielectric contrast
and/or low loss materials
0.01-0.0002  resonant structures (e.g,
λ/2 wires)
RCS ~ f 4D6 for electrically small objects, ~(area) for large objects
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Scattering Coefficients of Hydrometeors
f 4a6
Ice
Liquid
(parameters are sphere radii a in mm)
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