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Title: Pulse homodyne field disturbance sensor

A field disturbance sensor operates with relatively low power, provides an adjustable operating range, is not hypersensitive at close range, allows co-location of multiple sensors, and is inexpensive to manufacture. The sensor includes a transmitter that transmits a sequence of transmitted bursts of electromagnetic energy. The transmitter frequency is modulated at an intermediate frequency. The sequence of bursts has a burst repetition rate, and each burst has a burst width and comprises a number of cycles at a transmitter frequency. The sensor includes a receiver which receives electromagnetic energy at the transmitter frequency, and includes a mixer which mixes a transmitted burst with reflections of the same transmitted burst to produce an intermediate frequency signal. Circuitry, responsive to the intermediate frequency signal indicates disturbances in the sensor field. Because the mixer mixes the transmitted burst with reflections of the transmitted burst, the burst width defines the sensor range. The burst repetition rate is randomly or pseudo-randomly modulated so that bursts in the sequence of bursts have a phase which varies. A second range-defining mode transmits two radio frequency bursts, where the time spacing between the bursts defines the maximum range divided by two.
Inventors:
 [1]
  1. (Livermore, CA)
Issue Date:
OSTI Identifier:
871210
Assignee:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5682164
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:
pulse; homodyne; field; disturbance; sensor; operates; relatively; power; provides; adjustable; operating; range; hypersensitive; close; allows; co-location; multiple; sensors; inexpensive; manufacture; transmitter; transmits; sequence; transmitted; bursts; electromagnetic; energy; frequency; modulated; intermediate; burst; repetition; rate; width; comprises; cycles; receiver; receives; mixer; mixes; reflections; produce; signal; circuitry; responsive; indicates; disturbances; defines; randomly; pseudo-randomly; phase; varies; range-defining; mode; radio; time; spacing; maximum; divided; operating range; multiple sensors; repetition rate; radio frequency; electromagnetic energy; intermediate frequency; magnetic energy; frequency signal; sensor field; mixer mixes; sensor operates; close range; field disturbance; disturbance sensor; stable operating; allows co-location; adjustable operating; /342/

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