skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: SAR processing with non-linear FM chirp waveforms.

Abstract

Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.

Authors:
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
902597
Report Number(s):
SAND2006-7729
TRN: US200719%%11
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; OPTICAL RADAR; SIGNAL-TO-NOISE RATIO; WAVE FORMS; IMAGE PROCESSING; Synthetic Aperture Radar.; Radar.; Waveforms.-Calculations

Citation Formats

Doerry, Armin Walter. SAR processing with non-linear FM chirp waveforms.. United States: N. p., 2006. Web. doi:10.2172/902597.
Doerry, Armin Walter. SAR processing with non-linear FM chirp waveforms.. United States. doi:10.2172/902597.
Doerry, Armin Walter. 2006. "SAR processing with non-linear FM chirp waveforms.". United States. doi:10.2172/902597. https://www.osti.gov/servlets/purl/902597.
@article{osti_902597,
title = {SAR processing with non-linear FM chirp waveforms.},
author = {Doerry, Armin Walter},
abstractNote = {Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.},
doi = {10.2172/902597},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2006,
month =
}

Technical Report:

Save / Share:
  • Nonlinear FM waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.
  • Wideband radar systems, especially those that operate at lower frequencies such as VHF and UHF, are often restricted from transmitting within or across specific frequency bands in order to prevent interference to other spectrum users. Herein we describe techniques for notching the transmitted spectrum of a generated and transmitted radar waveform. The notches are fully programmable as to their location, and techniques are given that control the characteristics of the notches.
  • Chirp signals have evolved primarily from radar/sonar signal processing applications specifically attempting to estimate the location of a target in surveillance/tracking volume. The chirp, which is essentially a sinusoidal signal whose phase changes instantaneously at each time sample, has an interesting property in that its correlation approximates an impulse function. It is well-known that a matched-filter detector in radar/sonar estimates the target range by cross-correlating a replicant of the transmitted chirp with the measurement data reflected from the target back to the radar/sonar receiver yielding a maximum peak corresponding to the echo time and therefore enabling the desired range estimate.more » In this application, we perform the same operation as a radar or sonar system, that is, we transmit a “chirp-like pulse” into the target medium and attempt to first detect its presence and second estimate its location or range. Our problem is complicated by the presence of disturbance signals from surrounding broadcast stations as well as extraneous sources of interference in our frequency bands and of course the ever present random noise from instrumentation. First, we discuss the chirp signal itself and illustrate its inherent properties and then develop a model-based processing scheme enabling both the detection and estimation of the signal from noisy measurement data.« less
  • EPRI Research Project 502-8 was established to investigate advanced signal processing methods as applied to the ultrasonic inspection of turbine rotor bores. The rf waveform responses from near bore defects contain much information which can be used to characterize these flaws. This information is not used in conventional UT systems. The purpose of this effort has been to (1) determine which signal processing operations could be used to enhance the quality and interpretation of rotor bore inspection data, and (2) to investigate advanced methods of characterizing the defects using the rf waveforms to provide the inspector with additional knowledge asmore » to defect type. An outcome of this effort was to develop an Adaptive Learning Network (ALN) model tested using data recorded on the (retired) Kanawha and Connors Creek rotors. Subsequent destructive results showed that the ALN was able to discriminate accurately between inclusions and crack-like flaws in the Kanawha rotor.« less