Theory, Design, Analysis, and Implementation of a Spectrally Agile Frequency-Incrementing Reconfigurable (SAFIRE) Foward-Looking Ground Penetrating Radar

Open Access
Author:
Phelan, Brian Richard
Graduate Program:
Electrical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 09, 2016
Committee Members:
  • Ram M. Narayanan, Dissertation Advisor
  • Timothy J. Kane, Committee Chair
  • Michael T. Lanagan, Committee Member
  • Randy K. Young, Committee Member
  • Michael T. Lanagan, Outside Member
Keywords:
  • Stepped-Frequency
  • Frequency-Incrementing
  • Forward-Looking
  • Ground-Penetrating
  • Radar
  • GPR
  • Army Research Laboratory
  • ARL
  • Mine Detection
  • Thinned-Spectrum
  • Crowded Spectrum
  • FLGPR
  • IED
  • UXO
  • Synthetic-Aperture Radar
  • SAR
  • RF
  • Radio Frequency
  • Radio Frequency Interference
  • RFI
  • Recursive Sidelobe Mnimization
  • RSM
  • SAFIRE
  • Spectrally Agile Frequency Incrementing Reconfigurable
  • Signal-to-Clutter Ratio
  • SCR
  • Signal-to-Noise Ratio
  • SNR
  • Ultra-Wideband
  • UWB
  • Yuma
  • Yuma AZ
  • YPG
Abstract:
This thesis discusses the design, implementation, and verification of an ultra-wideband (UWB) stepped-frequency ground-penetrating radar (GPR). The main goal of the Spectrally Agile Frequency-Incrementing REconfigurable (SAFIRE) system was to detect buried and concealed landmines and improvised explosive devices (IEDs) from safe stand-off distances. The radar aims to accomplish this goal in the presence of clutter and radio frequency interference (RFI). This dissertation discusses basic stepped-frequency radar (SFR) principles, SAFIRE system specifications and measurements, theoretical performance of forward-looking GPRs for concealed target detection, experimental SAFIRE radar imagery, radar image formation, and applicable signal processing techniques. Traditional stepped-frequency waveforms consist of multiple pulses of narrowband signals (sinusoids). Unlike impulse-based UWB radars, SFRs have the ability to excise specific frequencies within their operating band, thus reducing interference to nearby systems. Furthermore, through spectral sensing techniques, the frequency bands where RFI is present can easily be removed. A brief synopsis of current state-of-the-art forward-looking GPRs used for concealed target detection is given. The rationale for the principal system specifications and user-controllability is given. System architecture and mixing scheme are discussed with a justification for both. Verification of the system's operational specifications was completed via laboratory measurements and theoretical analysis; the laboratory measurements included transmitted power, spectral purity, receiver gain, receiver noise figure, receiver noise floor, dynamic range, antenna measurements, and overall susceptibility to RFI. Thinned spectrum algorithms are discussed, and their performance on measured experiment data are provided. The dissertation concludes with a summary and discussion of suggested system improvements.