Impulse radar studfinder
First Claim
Patent Images
1. A portable device for locating a wall stud positioned behind a wall surface, comprising:
- means for radiating a sequence of electromagnetic impulses toward the wall;
non-ringing antenna means for receiving reflected electromagnetic signals from the wall;
a detection circuit connected to the antenna means for detecting a change in amplitude of the reflected electromagnetic signals from a fixed range behind the wall; and
indicator means connected to the detection circuit for indicating the change in amplitude of reflected electromagnetic signals whereby by moving the device adjacent to the wall, the change in amplitude of reflected electromagnetic signals from said fixed range caused by the stud in the wall as indicated by the indicating means defines the location of the wall stud.
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Abstract
An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.
317 Citations
20 Claims
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1. A portable device for locating a wall stud positioned behind a wall surface, comprising:
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means for radiating a sequence of electromagnetic impulses toward the wall; non-ringing antenna means for receiving reflected electromagnetic signals from the wall; a detection circuit connected to the antenna means for detecting a change in amplitude of the reflected electromagnetic signals from a fixed range behind the wall; and
indicator means connected to the detection circuit for indicating the change in amplitude of reflected electromagnetic signals whereby by moving the device adjacent to the wall, the change in amplitude of reflected electromagnetic signals from said fixed range caused by the stud in the wall as indicated by the indicating means defines the location of the wall stud. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus comprising:
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a pulse repetition frequency (PRF) generator for producing a sequence of pulses; a first step generator connected to the PRF generator for producing a sequence of transmit pulses; a transmit antenna connected to the first step generator for transmitting the transmit pulses toward a surface; a range delay generator connected to the PRF generator for producing a delayed sequence of pulses having a fixed delay relative to the transmit pulses; a second step generator connected to the range delay generator for producing a sequence of gating pulses; a receive antenna for receiving reflected pulses from an object in the path of the transmit pulses; an averaging sample/hold (S/H) circuit for sampling a plurality of reflected pulses to produce an average reflected signal; gating means connected between the receive antenna and the S/H circuit, and to the second step generator so that only reflected pulses from a fixed range are sampled by the S/H circuit; amplification means connected to the S/H circuit to amplify the average reflected signal; display means connected to the amplification means to display the amplified average reflected signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting a hidden object at a fixed distance behind a surface, comprising:
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transmitting a sequence of ultra-wideband (UWB) unipolar radar pulses without a carrier frequency from a detection position toward the surface; detecting reflected pulses from a fixed range from the detection position, said fixed range corresponding to the fixed distance of the object behind the surface; averaging the detected pulses over repeated pulses to produce a measured signal; measuring changes in amplitude of the measured signal produced by moving laterally along the surface so that transmitted pulses are reflected by the object to define the location of the object.
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Specification