Imaging synthetic aperture radar

Patent · Wed Jan 01 00:00:00 EST 1997

OSTI ID:870851

Burns, Bryan L ^[1]; Cordaro, J Thomas ^[2]

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1. Tijeras, NM
2. Albuquerque, NM

A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-76
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 5608404
• OSTI ID: 870851
• Country of Publication: United States
• Language: English

Related Subjects

imaging
synthetic
aperture
radar
linear-fm
method
apparatus
produce
real-time
image
arranging
returned
signals
plurality
subaperture
arrays
columns
array
samples
dechirped
baseband
pulses
including
processing
obtain
coarse-resolution
azimuth
fine-resolution
range
lastly
combine
processed
subapertures
final
efficiency
achieved
transmitted
signal
local
oscillator
mixed
varied
pulse-to-pulse
basis
function
motion
moreover
novel
circuit
adjust
sampling
location
sample
rate
combined
greatly
reduces
time
hardware
steps
implementing
window
stabilizing
central
reference
respect
doppler
frequency
sorting
compressing
standard
fourier
transforms
stabilization
accomplished
vector
multiplication
waveforms
generated
synthesized
integrated
circuits
migration
simple
particularly
useful
feature
correcting
spatially
varying
phase
errors
prior
application
autofocus
process
radar motion
greatly reduces
aperture radar
phase error
processing time
particularly useful
integrated circuits
integrated circuit
fourier transform
processing steps
synthetic aperture
local oscillator
varying phase
processing step
phase errors
oscillator signal
transmitted signal
doppler frequency
returned signal
subaperture array
greatly reduce
fourier transforms
imaging radar
aperture arrays
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