ECEN5633 Radar Theory
Lecture #22
2 April 2015
Dr. George Scheets
www.okstate.edu/elec-eng/scheets/ecen5633
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Read 4.3
Problems 4.10, Web 8 & 9
Design Problem due 7 April (Live), 9 April (DL)
 Late turn in fee = -1 per working day
Reworked exams due 14 April (Live)
Quiz #2 Results
Hi = 13.6, Low = 6.50, Ave = 11.33, σ =2.71
2015 OSU ECE Spring Banquet
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Hosted by Student Branch of IEEE
Wednesday, 15 April, at Meditations
Doors open at 5:30 pm, meal at 6:00 pm
Cash Bar
Sign up in ES202 to reserve your seat(s)
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Speakers: Ron Sinnes (Level3, Director IP)
& Eric Miller (VYVX, Sports Manager)
Dress is Business Casual
Many door prizes available!
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$5 if pay in advance (< 8 April) &
resume submitted to ieee@okstate.edu
$10 on 9 & 10 April. (A $20 value.)
Known best: 8.4" Samsung Galaxy Tab S, two Fluke Multimeters
+6 points extra credit
All are invited!
Sponsored in part by:
Coherent Detection
RCVR Local Oscillator
PLL seeks echo frequency & phase lock
tp = 1 μsec, fc = 10 GHz → 10,000 cycles
 Will take some time
Some echo energy is lost
Matched Filter fed sinusoid until lock
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 Area
around zero
Locked → Matched Filter fed baseband pulse
 Best Potential Performance
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Non-coherent Detection
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RCVR Local Oscillator at transmitted fc
Stationary target with respect to radar
Zero doppler, baseband pulse to Matched Filter
Moving target with respect to radar
Wide variety of signals fed to Matched Filter
May get almost nothing when sampled
Quadrature Detection
If energy not in I channel, it's in Q channel
Ambiguity Function
+∞
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X(τ,ν) = ∫ g(t)g*(t - τ) ej2πνt dt
-∞
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X(τ,0) = Autocorrelation
of complex envelope g(t)
= Matched Filter output envelope
 at
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Zero doppler
X(0,ν) = F.T. of signal's magnitude (AM)
Ambiguity Function
+∞
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X(τ,ν) = ∫ g(t)g*(t - τ) ej2πνt dt
-∞
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For most accurate range estimates
 Want
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For most accurate radial velocity estimate
 Want
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narrow width along τ (time) axis
narrow width along ν (frequency) axis
Since X(0,0) = 1 &
Volume of |X(τ,ν)|2 = 1 (if complex E = 1)
May not be able to do both
Selected e Integrals
Gaussian Pulse Ambiguity Function
 tp
= 1.0
source: west 5633 notes
Matched Filter Outputs as fd ↑
fd = 1
fd = 2
fd = 3
fd = 5
Rectangular Pulse Ambiguity Function
source: skolnik, Introduction to Radar Systems