Homodyne impulse radar hidden object locator

Patent · 01 January 1996

OSTI ID:870399

McEwan, Thomas E ^[1]

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1. Livermore, CA

An electromagnetic detector is designed to locate an object hidden behind a separator or a cavity within a solid object. The detector includes a PRF generator for generating 2 MHz pulses, a homodyne oscillator for generating a 2 kHz square wave, and for modulating the pulses from the PRF generator. A transmit antenna transmits the modulated pulses through the separator, and a receive antenna receives the signals reflected off the object. The receiver path of the detector includes a sample and hold circuit, an AC coupled amplifier which filters out DC bias level shifts in the sample and hold circuit, and a rectifier circuit connected to the homodyne oscillator and to the AC coupled amplifier, for synchronously rectifying the modulated pulses transmitted over the transmit antenna. The homodyne oscillator modulates the signal from the PRF generator with a continuous wave (CW) signal, and the AC coupled amplifier operates with a passband centered on that CW signal. The present detector can be used in several applications, including the detection of metallic and non-metallic objects, such as pipes, studs, joists, nails, rebars, conduits and electrical wiring, behind wood wall, ceiling, plywood, particle board, dense hardwood, masonry and cement structure. The detector is portable, light weight, simple to use, inexpensive, and has a low power emission which facilitates the compliance with Part 15 of the FCC rules.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 5512834
• OSTI ID: 870399
• Country of Publication: United States
• Language: English

Related Subjects

/324/342/
15
amplifier
antenna
antenna transmits
applications
bias
board
cavity
ceiling
cement
centered
circuit
circuit connected
compliance
conduits
connected
continuous
continuous wave
coupled
cw
dc
dc bias
dense
designed
detection
detector
electrical
electrical wiring
electromagnetic
emission
facilitates
fcc
filters
generating
generator
hardwood
hidden
hold
hold circuit
homodyne
impulse
impulse radar
including
inexpensive
joists
khz
level
light
light weight
locate
locator
masonry
metallic
mhz
modulated
modulated pulse
modulated pulses
modulates
modulating
nails
non-metallic
operates
oscillator
particle
passband
path
pipes
plywood
portable
power
prf
pulse radar
pulses
pulses transmitted
radar
rebars
receive
receive antenna
receiver
receives
rectifier
rectifier circuit
rectifying
reflected
rf generator
rules
sample
separator
shifts
signal
signals
signals reflected
simple
solid
square
square wave
structure
studs
synchronously
transmit
transmit antenna
transmits
transmitted
wall
wave
weight
wiring
wood