ECEN5633 Radar TheoryECEN5633 Radar TheoryLecture #28 23 April 2015Lecture #28 23 April 2015Dr. George ScheetsDr. George Scheetswww.okstate.edu/elec-eng/scheets/ecen5633www.okstate.edu/elec-eng/scheets/ecen5633

ECEN5633 Radar TheoryECEN5633 Radar TheoryLecture #28 23 April 2015Lecture #28 23 April 2015Dr. George ScheetsDr. George Scheetswww.okstate.edu/elec-eng/scheets/ecen5633www.okstate.edu/elec-eng/scheets/ecen5633

Read 6.4Read 6.4 Problems 6.1, Web 15 & 16Problems 6.1, Web 15 & 16 Design Problem ReworkDesign Problem Rework

Due by midnight, 28 April (Live)Due by midnight, 28 April (Live) Due by midnight, 29 April (DL)Due by midnight, 29 April (DL)

Quiz ReworkQuiz Rework Due by midnight, 29 April (Live)Due by midnight, 29 April (Live)

Final Exam Final Exam 0800 – 0950, Thursday, 7 May0800 – 0950, Thursday, 7 May No Later than Thursday, 14 MayNo Later than Thursday, 14 May

Winning DesignWinning Design Replogle & WashbourneReplogle & Washbourne 5.35 GHz center frequency5.35 GHz center frequency 93 element phased array, G = 17,51793 element phased array, G = 17,517 LNA with lowest Temp & Gain = 1,300LNA with lowest Temp & Gain = 1,300 Single Pulse, Coherent DetectionSingle Pulse, Coherent Detection

.9486 of pulse energy captured.9486 of pulse energy captured ChirpChirp

Sweep range of 1.154 MHzSweep range of 1.154 MHz $12.73 Million$12.73 Million

Spread Spectrum RadarSpread Spectrum Radar

Uses > minimum required BWUses > minimum required BW Chirp Radar is a formChirp Radar is a form

PPrr still valid (RF power out of antenna) still valid (RF power out of antenna)

Reduce PReduce Prr by 3 dB prior to calculating P(Hit) by 3 dB prior to calculating P(Hit) Direct Conversion ReceiverDirect Conversion Receiver

Example) Direct Conversion ReceiverExample) Direct Conversion Receiver

2 μwatt

Mixer&

Matched Filter

1/4 watt signalA watts noise

Detector

Standard

2 μwatt

Mixer&

Matched Filter

1/16 watt signalA/2 watts noise

Detector

Chirp

F-22 RaptorF-22 Raptor

Uses Frequency Hopping

Source: Wikipedia

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

X

X

X

X

X

X

Original Clone Overlap

Time

Fre

quen

cy

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

X

X

X

X

X

X

Original No Shift Overlap

5

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

X

X

X

X

X

X

Original 1 Shift Right Overlap

5 0

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

XX

X

X

X

X

Original 1 Shift Right1 Shift Up

Overlap

5 04

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

XX

X

X

X

X

Original 1 Shift Right1 Shift Up1 Shift Left

Overlap

5 040

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

XX

X

X

X

X

Original 1 Shift Right1 Shift Up2 Shifts Left

Overlap

5 0400

Estimating FH AmbiguityEstimating FH AmbiguityContinuingwith this process…(Need 4 more columns & 4 more rows tocomplete).

5 04000 00000

0 0000 0 0

00

00

34

3

X

X

X

X

X

Original

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

X

X

X

X

X

X

Original Clone Overlap

Estimating FH AmbiguityEstimating FH Ambiguity

Original No Shift Overlap

5X

X

X

X

X

X

X

X

X

X

Estimating FH AmbiguityEstimating FH Ambiguity

Original 1 Shift Right Overlap

5 0X

X

X

X

X

X

X

X

X

X

Estimating FH AmbiguityEstimating FH Ambiguity

Original 1 Shift Right1 Shift Up

Overlap

5 00X

X

X

X

X

X

X

X

X

X

Estimating FH AmbiguityEstimating FH Ambiguity

Original 1 Shift Right1 Shift Up1 Shift Left

Overlap

5 000X

X

X

X

X

X

X

X

X

X

Estimating FH AmbiguityEstimating FH Ambiguity

Original 1 Shift Right1 Shift Up2 Shifts Left

Overlap

5 0000X

X

X

X

X

X

X

X

X

X

Estimating FH AmbiguityEstimating FH Ambiguity

Original Overlap

5 00000 20030

3 0000 0 0

02

00

00

0X

X

X

X

X

Continuingwith this process…(Need 4 more columns & 4 more rows tocomplete).

Estimating FH AmbiguityEstimating FH Ambiguity

X

X

X

X

X

Original Overlap

5 01001 01001

0 1010 0 1

00

00

01

0Costas Signal(Need 4 more columns & 4 more rows tocomplete).

Costas Signals FH AmbiguityCostas Signals FH Ambiguity

Overlap(EstimatedAmbiguityFunction)

FH Sequences with 1 FH Sequences with 1 coincidencecoincidence

5*4*3*2 = 120 sequences5*4*3*2 = 120 sequences With 5 hops per pulseWith 5 hops per pulse 1 hop to each frequency1 hop to each frequency

40 possible Costas sequences40 possible Costas sequences Best ChoiceBest Choice

Example: Frequency Hopping Ambiguity Function

Example: Frequency Hopping Ambiguity Function

source: Levanon,, RADAR PRINCIPLESWiley Interscience,, 1988