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Title: Homodyne impulse radar hidden object locator

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 ismore » portable, light weight, simple to use, inexpensive, and has a low power emission which facilitates the compliance with Part 15 of the FCC rules.« less
Inventors:
 [1]
  1. (Livermore, CA)
Issue Date:
OSTI Identifier:
870399
Assignee:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5512834
Contract Number:
W-7405-ENG-48
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
homodyne; impulse; radar; hidden; locator; electromagnetic; detector; designed; locate; separator; cavity; solid; prf; generator; generating; mhz; pulses; oscillator; khz; square; wave; modulating; transmit; antenna; transmits; modulated; receive; receives; signals; reflected; receiver; path; sample; hold; circuit; coupled; amplifier; filters; dc; bias; level; shifts; rectifier; connected; synchronously; rectifying; transmitted; modulates; signal; continuous; cw; operates; passband; centered; applications; including; detection; metallic; non-metallic; pipes; studs; joists; nails; rebars; conduits; electrical; wiring; wood; wall; ceiling; plywood; particle; board; dense; hardwood; masonry; cement; structure; portable; light; weight; simple; inexpensive; power; emission; facilitates; compliance; 15; fcc; rules; impulse radar; light weight; circuit connected; continuous wave; receive antenna; dc bias; transmit antenna; square wave; hold circuit; rf generator; signals reflected; pulses transmitted; modulated pulse; electrical wiring; pulse radar; rectifier circuit; modulated pulses; antenna transmits; /324/342/

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