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OS-CFAR and CA-CFAR Performance Study in Measured
Land Clutter
by Asem Melebari, M. Y. Abdul Gaffar, R. De Wind,
Amer Melebari, F. Alzaid
1 National Center for Sensors and Defense Systems Technology
Problem Statement
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Detect slow moving ground vehicles in a Saudi Arabia environment and achieve a constant false alarm rate.
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Problem Statement
1. Delores Johnson , (2014), Tawazun military vehicles [ONLINE]. Available at: http://www.thenational.ae/uae/technology/military-special-forces-to-meet-at-amman-conference.
Figure 1: Tawazun military vehicles 1
2. Ministry of Defense UK [ONLINE]. Available at: http://www.defenceimagery.mod.uk
Figure 2: Military vehicles 1
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• Introduction
• Radar & RSP configurations
• Measured land clutter
• Detection in measured land Clutter
• Future Work
• Conclusion
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Outline
Introduction
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• CFAR algorithms fix the false alarm rate.
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Introduction
Figure 3: CFAR processor diagram3
3. Richards, Mark A.; James A. Scheer; William A. Holm, Principles of Modern Radar, Raleigh, NC: SciTech Publishing, 2010.
Radar & RSP configurations
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• X-band radar.
• The transmitted pulse was
a square pulse with linear
frequency modulation.
• The waveform bandwidth
was 400 MHz
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Radar Configuration
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• Digital Down mixing.
• Transmitted pulse was windowed in the pulse compression process.
• Windowing was applied in slow time before Doppler processing.
• Two CFAR algorithms were used: Cell Averaging CFAR (CA-CFAR) and Ordered Statistic CFAR (OS-CFAR).
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RSP Configuration
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• Ignore the Doppler bins close to zero Doppler in detection.
• Point targets were added in the Range-Doppler map.
• The target fluctuation was set to be Swerling one.
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RSP Configuration
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CFAR Windows
Doppler
Range
Range
a. 2-D
Doppler
Range
c. 1-D Doppler
b. 1-D Range
CUT
Guard Cells
Reference Cells
Ranged. 2-D Mod.
Doppler
Doppler / p
ulses
Measured Land Clutter
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Date Farm
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Date Farm
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Detection in Measured Land Clutter
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• PD: probability of detection.
• PFA: probability of false alarm.
• PFA error: relative error between desired PFA and the actual PFA.
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Detection in Land Clutter
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OS-CFAR
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OS-CFAR
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CA-CFAR
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CA-CFAR
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• Windowing in slow time produces correlation in slow time.
• Windowing the transmitted pulse causes a mismatch in the pulse compression process.
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Windowing Effect
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CFAR Windows
Doppler
Range
Range
a. 2-D
Doppler
Range
c. 1-D Doppler
b. 1-D Range
CUT
Guard Cells
Reference Cells
Ranged. 2-D Mod.
Doppler
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Date Farm
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OS-CFAR
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OS-CFAR
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CA-CFAR
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CA-CFAR
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Future Work
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• Fix the PFA when windowing function is applied.
• Use more various types of clutter in different weather condition.
• Detecting very slow moving targets.
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Future Work
Conclusion
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• Detecting land target is similar to detection in noise for fast moving targets.
• Windowing in slow time or the transmit pulse causes a large error in the PFA.
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Conclusion
Thank You
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