A J Gasiewski remote sensing course notes lecture12

60 Pages·01.506 MB·English

by  A J Gasiewski

EECCEENN 55225544
Remote Sensing Signals and Systems
Professor Albin J. Gasiewski
Lecture #12 – February 23, 2012
ECOT 246
303-492-9688 (O)
[email protected]
CCllasses: EECCCCSS 11BB1144 TTRR 99:3300-1100:4455 AAMM
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Last Lecture
• FT property of lenses
•• HHuummaann eeyyee
• Telescopes
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Today’s Lecture
• Direct detection radiometry
• Digital sampling resolution
• LLooww-ppaassss RRCC ffiilltteerriinngg//ssaammpplliinngg
• Gain, noise figure, Friis formula
• YY-ffacttor
• Gain & offset fluctuations
• Homodyne detection
• LLiinneeaarr ccaalliibbrraattiioonn
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ECEN 5254 Remote Sensing Signals & Systems Spring 2012 University of Colorado at Boulder
Direct Detection Radiometry
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Direct Detection Radiometer
TT ((ff)) == TT ((ff)) ++ TT ((ff))
SYS A R BBPPFF LPF
h (t)
vvvvvvv (((((((ttttttt))))))) BBBB BBBBB vvvvvv ((((((tttttt)))))) vvvv ((((tttt)))) LPF v (t)
AAAAAAA BBBBBB DDDD o
1
TT ((KK)) 1
RR
t
----ffff fffff τ
oooo ooooo i
GGGGGGGGGG ((((((((((ppppppppppoooooooooowwwwwwwwwweeeeeeeeeerrrrrrrrrr)))))))))) BBBBBBBBBB,,,,, ffffffffff ((((((((((vvvvvvvvvv))))))))))22222 ττττττττττ
iiiiiiiiii
ooooo
LLeett vv ((tt)) bbee rraannddoomm,, zzeerroo mmeeaann,, GGaauussssiiaann::
AA
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Spectrum of v and v
A B
TT ((ff)) == TT ((ff)) ++ TT ((ff))
SYS A R BPF
h (t)
v (t) BBBB BBBBB v (t)
LPF
A B
1
TT ((KK)) 1
RR
t
----ffff fffff τ
oooo ooooo i
GG ((ppoowweerr)) BB, ff
o
f
ff
-f f
o o
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Spectrum of v
D
TT ((ff)) == TT ((ff)) ++ TT ((ff))
SYS A R BPF
h (t)
BBBB BBBBB v (t) v (t)
LPF
B D
1
TT ((KK)) 1
RR
t
----ffff fffff τ
oooo ooooo i
GG ((ppoowweerr)) BB, ff ((vv))2
o
Lemma: For any four CZMGRVs:
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Spectrum of v (cont’d)
D
9
Spectrum of v (cont’d)
D
*
ff ff
-f f -f f
o o o o
f
~~ ~~
-2f -B -2f -2f +B -B 0 B 2f -B 2f 2f +B
o o o o o o 10
Spectrum of v
o
LPF
h (t)
BBBB BBBBB v (t) LPF v (t)
D
o
1
T (K) 1
R
tt
----ffffffff ffffffffff τ
oooo ooooo i
h (t)
LPF
τ 2
|H (f )|2
i
LPF
11 || ||22
= τ 2sinc2(fτ )
i i
t f
ττ
11//ττ
ii ii
1/τ « B (typical)
i
f
-B 0 τ -1 B
11
i