07-07-2012, 03:30 PM
Detection of Targets in Noise and Pulse Compression Techniques
[attachment=27162]
Disclaimer of Endorsement and Liability
• The video courseware and accompanying viewgraphs presented on this server were prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor the Massachusetts Institute of Technology and its Lincoln Laboratory, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, products, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof, or any of their contractors or subcontractors or the Massachusetts Institute of Technology and its Lincoln Laboratory.
• The views and opinions expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or any of their contractors or subcontractors
Integration of Radar Pulses
• Improve ability of radar to detect targets by combining the returns from multiple pulses
• Coherent Integration
– No information lost (amplitude or phase)
• Non-coherent integration techniques
– Some information lost (phase)
– Non-coherent (video) Integration
– Binary Integration
– Cumulative detection
– For most cases, coherent integration is more efficient than non- coherent integration
Motivation for Pulse Compression
• Hard to get “good” average power and resolution at the same time using a pulsed CW system
– Higher average power is proportional to pulse width
– Better resolution is inversely proportional to pulse width
• A long pulse can have the same bandwidth (resolution) as a short pulse if the long pulse is modulated in frequency or phase
• These pulse compression techniques allow a radar to simultaneously achieve the energy of a long pulse and the resolution of a short pulse
Summary
• Detection of Targets in Noise
– Both target properties and radar design features affect the ability to detect signals in noise
– Coherent and non-coherent integration pulse integration can improve target detection
– Adaptive thresholding (CFAR) techniques are needed in realistic environments
• Pulse compression offers a means to simultaneous have high average power and good resolution
– A long pulse can have the same bandwidth (resolution) as a short pulse, if it is modulated in frequency or phase
– Phase-encoded pulse compression divides long pulses into binary encoded sub-pulses
– With frequency-encoded pulse compression, the radar frequency is increased linearly as the pulse is transmitted
[attachment=27162]
Disclaimer of Endorsement and Liability
• The video courseware and accompanying viewgraphs presented on this server were prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor the Massachusetts Institute of Technology and its Lincoln Laboratory, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, products, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof, or any of their contractors or subcontractors or the Massachusetts Institute of Technology and its Lincoln Laboratory.
• The views and opinions expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or any of their contractors or subcontractors
Integration of Radar Pulses
• Improve ability of radar to detect targets by combining the returns from multiple pulses
• Coherent Integration
– No information lost (amplitude or phase)
• Non-coherent integration techniques
– Some information lost (phase)
– Non-coherent (video) Integration
– Binary Integration
– Cumulative detection
– For most cases, coherent integration is more efficient than non- coherent integration
Motivation for Pulse Compression
• Hard to get “good” average power and resolution at the same time using a pulsed CW system
– Higher average power is proportional to pulse width
– Better resolution is inversely proportional to pulse width
• A long pulse can have the same bandwidth (resolution) as a short pulse if the long pulse is modulated in frequency or phase
• These pulse compression techniques allow a radar to simultaneously achieve the energy of a long pulse and the resolution of a short pulse
Summary
• Detection of Targets in Noise
– Both target properties and radar design features affect the ability to detect signals in noise
– Coherent and non-coherent integration pulse integration can improve target detection
– Adaptive thresholding (CFAR) techniques are needed in realistic environments
• Pulse compression offers a means to simultaneous have high average power and good resolution
– A long pulse can have the same bandwidth (resolution) as a short pulse, if it is modulated in frequency or phase
– Phase-encoded pulse compression divides long pulses into binary encoded sub-pulses
– With frequency-encoded pulse compression, the radar frequency is increased linearly as the pulse is transmitted