Range-gated field disturbance sensor with range-sensitivity compensation
First Claim
1. A sensor comprising:
- a transmitter which transmits a sequence of transmitted bursts of electromagnetic energy to produce a sensor field, the sequence of bursts having a burst repetition rate, and each burst having a burst width and comprising a number of cycles at a transmitter frequency;
a receiver which receives electromagnetic energy at the transmitter frequency, including a mixer which mixes a transmitted burst with reflections of the transmitted burst to produce an intermediate frequency signal, so that the burst width defines a sensor range; and
circuitry, coupled to the receiver and responsive to the intermediate frequency signal, to indicate disturbances in the sensor field.
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Accused Products
Abstract
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 pseudorandomly modulated so that bursts in the sequence of bursts have a phase which varies.
196 Citations
29 Claims
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1. A sensor comprising:
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a transmitter which transmits a sequence of transmitted bursts of electromagnetic energy to produce a sensor field, the sequence of bursts having a burst repetition rate, and each burst having a burst width and comprising a number of cycles at a transmitter frequency; a receiver which receives electromagnetic energy at the transmitter frequency, including a mixer which mixes a transmitted burst with reflections of the transmitted burst to produce an intermediate frequency signal, so that the burst width defines a sensor range; and circuitry, coupled to the receiver and responsive to the intermediate frequency signal, to indicate disturbances in the sensor field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A sensor comprising:
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a modulated transmitter which transmits a sequence of transmitted bursts of electromagnetic energy, the sequence of transmitted bursts having a burst repetition rate, and each burst having a burst width and comprising a number of cycles at a transmitter frequency, the sequence of bursts being modulated at an intermediate frequency; a receiver which receives electromagnetic energy at the transmitter frequency, including a mixer which mixes a transmitted burst with reflections of the same transmitted burst to produce an intermediate frequency signal, so that the burst width defines a sensor range of about one-half the burst width; and circuitry, coupled to the receiver and responsive to the intermediate frequency signal, to indicate motion within the sensor range. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A sensor comprising:
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a transmitter which transmits a sequence of transmitted bursts of electromagnetic energy to produce a sensor field, the sequence of bursts having a randomly or pseudo randomly modulated burst repetition rate, and each burst having a burst width and comprising a number of cycles at a transmitter frequency; frequency modulation circuitry coupled to the transmitter which switches the transmitter frequency between at least a first frequency and a second frequency at an intermediate frequency; a receiver which receives electromagnetic energy at the transmitter frequency, including a mixer which mixes a transmitted burst with reflections of the transmitted burst to produce an intermediate frequency signal, so that the burst width defines a sensor range; and circuitry, coupled to the receiver and responsive to the intermediate frequency signal, to indicate disturbances in the sensor field. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification