Performance Analysis of LFM Pulse Compression Radar under Effect of Convolution Noise Jamming Eng.: Ahmed Abdo AbouelFadl Assoc. Prof. Dr: Alaauddeen Hussien Asseesy Dr. :Mohamed Samir Abdellatif Assoc. Prof. Dr.: Fathy Abdel Kader

Outlines Introduction. Problem Statement and Objectives. Radar Model. Convolution Jamming Model. LFM-PC Radar Response to Convolution Jamming. Conclusions.

How to solve this contradiction? Introduction Radar designer has two choices for the radar pulse width Long Pulse Width High Average Power High Detection Range Poor Range Resolution Short Pulse Width Low Average Power Short Detection Range High Range Resolution How to solve this contradiction?

Introduction Pulse Compression What about modulation inside the pulse? Good Range Resolution High Detection Range High Processing Gain High Jamming Immunity Pulse Compression What about modulation inside the pulse?

Introduction Pulse Compression Waveforms Supports high Doppler shifts. Frequency Modulation LFM NLFM Stepped Frequency Waveform (SFW) Costas Codes Phase Coding Binary Phase Coding Frank Codes Pseudo-Random (PRN) Codes Supports high Doppler shifts. Time side lobes performance remains excellent with high Doppler shifts. Used with high-speed targets with extremely high time bandwidth products. Compression Ratio = Time Bandwidth Product (B.T)

Problem Definition and Objectives To study the effect of convolution jamming on the detection of LFM-PC radar which has been proposed earlier against SAR. To determine the minimum required Jamming –to –Signal Ratio (JSR) by convolution noise jamming to be effective against LFM-PC search radars.

Problem Definition and Objectives To achieve these objectives, the following tasks have been done: LFM PC radar simulation model Quantitative and qualitative verification of the radar model Modeling and simulation of convolution jamming Studying the response of LFM-PC radar to convolution jamming

Doppler Processor and CFAR Radar Model Radar Block Diagram Waveform Generator Mixer Power Amplifier Duplexer Antenna Low Noise Amplifier Mixer Weighting Filter Matched Filter IF Amplifier/Filter Doppler Processor and CFAR Video Amplifier Display

Radar Model Radar Model Parameters Radar Model PRF[Hz] PW[µs] BW [MHz] Compression Ratio Date VARIANT 3000-9000 10 6 60 2003 TRS-3033 Fractions of 5300 2.7 3.7 APS-143C 200, 1500, 800, 400 5 ,17 10, 14 50,240 2007 SPY-1 12.7 127 2012 DA-08 500,1000 34,68 1.7 57,115 2013 LW-08 500,100 35,69 58,117

Radar Model Radar Model Parameters Target Parameters PRF[KHz] PW[µs] BW [MHz] Compression Ratio Fs[MHz] 2 100 15 1500 67.1 Range[Km] Doppler[KHz] Velocity [Km/min] 185.7263 7 21

Radar Model Radar Model Simulation Block Diagram min Generated Radar Signal Time Domain Frequency Domain Sidelobes Matched Filter Target location Output Waveform Output SNR Improvement Factor MTD (Doppler Processor) Output Doppler Processing gain Probability of Detection Fixed Threshold CA-CFAR GO-CFAR Weighting windows

Matched Filter Improvement 38.7dB Total Radar Processing Gain 50.7dB Radar Model Radar Model Processing Gain Matched Filter Improvement 38.7dB MTD Gain 12dB Total Radar Processing Gain 50.7dB Signal Improvement Factor 31.7 dB Noise Loss Factor 7 dB

Radar Model CA-CFAR Comparator Decision Threshold Doppler Cell#1 window window Guard Cells Doppler Cell # M Cell Under Test (CUT) Constant Factor Comparator Average Decision CA-CFAR Threshold

Radar Model GO-CFAR Comparator Decision Threshold Doppler Cell#1 window window Guard Cells Doppler Cell # M Cell Under Test (CUT) Constant Factor Comparator Greatest Of Decision GO-CFAR Threshold

Radar Model Radar Detection

Convolution Jamming Model FFT IFFT Convolution Jamming Signal Intercepted Radar Signal FFT Pulsed Jamming

Convolution Jamming Model The convolution jamming signal can be expressed as:

Convolution Jamming Model In frequency domain, the power spectral density of the convolution jamming signal can be expressed as:

Convolution Jamming Model JSR=-5 dB and SNR= -30 dB

LFM-PC Radar Response to Convolution Jamming The output of MF to convolutional jamming is:

LFM-PC Radar Response to Convolution Jamming JSR=15 dB and SNR= -30 dB JSR=25 dB and SNR= -30 dB

LFM-PC Radar Response to Convolution Jamming JSR=25 dB and SNR= -30 dB MTD CA-CFAR GO-CFAR Fixed Threshold

LFM-PC Radar Response to Convolution Jamming CA-CFAR GO-CFAR

Conclusions An LFM-PC search radar model has been introduced. It provides more than 50 dB processing gain over conventional pulse Doppler radars. To be effective, convolution jamming signal needs about 30 dB JSR against the proposed radar model for both detector types (CA-CFAR and GO-CFAR). Although the advantage it introduces over conventional AWGN(which needs 34 dB), convolution jamming still requires high JSR which may be unpractical in many cases.

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