ECEN5633 Radar Theory Lecture #28 23 April 2015 Dr. George Scheets n Read 6.4 n Problems 6.1, Web 15 & 16 n Design Problem Rework u Due by midnight, 28 April (Live) u Due by midnight, 29 April (DL) n Quiz Rework u Due by midnight, 29 April (Live) n Final Exam u 0800 – 0950, Thursday, 7 May u No Later than Thursday, 14 May

Winning Design n Replogle & Washbourne n 5.35 GHz center frequency n 93 element phased array, G = 17,517 n LNA with lowest Temp & Gain = 1,300 n Single Pulse, Coherent Detection u.9486 of pulse energy captured n Chirp u Sweep range of MHz n $12.73 Million

Spread Spectrum Radar n Uses > minimum required BW n Chirp Radar is a form u P r still valid (RF power out of antenna) u Reduce P r by 3 dB prior to calculating P(Hit) F Direct Conversion Receiver

Example) Direct Conversion Receiver 2 μwatt Mixer & Matched Filter 1/4 watt signal A watts noise Detector Standard 2 μwatt Mixer & Matched Filter 1/16 watt signal A/2 watts noise Detector Chirp

F-22 Raptor Uses Frequency Hopping Source: Wikipedia

Estimating FH Ambiguity X X X X X X X X X X OriginalClone Overlap Time Frequency

Estimating FH Ambiguity X X X X X X X X X X OriginalNo Shift Overlap 5

Estimating FH Ambiguity X X X X X X X X X X Original1 Shift Right Overlap 5 0

Estimating FH Ambiguity X X X X X X X X X X Original1 Shift Right 1 Shift Up Overlap 5 0 4

Estimating FH Ambiguity X X X X X X X X X X Original1 Shift Right 1 Shift Up 1 Shift Left Overlap

Estimating FH Ambiguity X X X X X X X X X X Original1 Shift Right 1 Shift Up 2 Shifts Left Overlap

Estimating FH Ambiguity Continuing with this process… (Need 4 more columns & 4 more rows to complete) X X X X X Original

Estimating FH Ambiguity X X X X X X X X X X OriginalClone Overlap

Estimating FH Ambiguity OriginalNo Shift Overlap 5 X X X X X X X X X X

Estimating FH Ambiguity Original 1 Shift Right Overlap 5 0 X X X X X X X X X X

Estimating FH Ambiguity Original 1 Shift Right 1 Shift Up Overlap X X X X X X X X X X

Estimating FH Ambiguity Original 1 Shift Right 1 Shift Up 1 Shift Left Overlap X X X X X X X X X X

Estimating FH Ambiguity Original 1 Shift Right 1 Shift Up 2 Shifts Left Overlap X X X X X X X X X X

Estimating FH Ambiguity Original Overlap X X X X X Continuing with this process… (Need 4 more columns & 4 more rows to complete).

Estimating FH Ambiguity X X X X X Original Overlap Costas Signal (Need 4 more columns & 4 more rows to complete).

Costas Signals FH Ambiguity Overlap (Estimated Ambiguity Function) n FH Sequences with 1 coincidence n 5*4*3*2 = 120 sequences u With 5 hops per pulse u 1 hop to each frequency n 40 possible Costas sequences u Best Choice

Example: Frequency Hopping Ambiguity Function source: Levanon,, RADAR PRINCIPLES Wiley Interscience,, 1988