Laser-based speed measuring device
First Claim
1. A timing analysis circuit comprisinga clock producing a periodic clock signal defining a clock period;
- an input supplying start and end pulses defining an elapsed time period, said pulses having respective start and end arrival times, and said arrival times having respective fractional portions which fall within different individual regions of said clock period;
timing interpolation circuitry connected to receive said clock signal and said start and end pulses, said timing interpolation circuitry being configured to;
output an integral clock count reflective of the number of whole said clock periods elapsing between said start and end pulse arrival times,generate a pair of calibration pulses defining an interpolation interval, and process said calibration pulses to produce calibration clock values reflective of the relative spacing in time of said calibration pulses; and
interpolate said respective fractional portions within said interpolation interval to produce start and end clock values reflective of said respective fractional portions, said start and end clock values being defined with respect to said calibration pulses; and
means for acquiring counts comprising the number of integral said clock periods elapsing between said start and end pulses, said start and end clock values, and said calibration clock values, said means for acquiring counts being connected to said timing interpolation circuitry;
wherein said self-calibrating interpolation is performed at least once each time a measurement of the elapsed time is made.
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Accused Products
Abstract
A laser speed detector is described which includes a laser rangefinder which determines the time-of-flight of an infrared laser pulse to a target and a microprocessor-based microcontroller. The device is small enough to be easily hand-held, and includes a trigger and a sighting scope for a user to visually select a target and to trigger operation of the device upon the selected target. The laser rangefinder includes self-calibrating interpolation circuitry, a digital logic-operated gate for reflected laser pulses in which both the "opening" and the "closing" of the gate can be selectably set by the microcontroller, and dual collimation of the outgoing laser pulse such that a minor portion of the outgoing laser pulse is sent to means for producing a timing reference signal.
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Citations
16 Claims
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1. A timing analysis circuit comprising
a clock producing a periodic clock signal defining a clock period; -
an input supplying start and end pulses defining an elapsed time period, said pulses having respective start and end arrival times, and said arrival times having respective fractional portions which fall within different individual regions of said clock period; timing interpolation circuitry connected to receive said clock signal and said start and end pulses, said timing interpolation circuitry being configured to; output an integral clock count reflective of the number of whole said clock periods elapsing between said start and end pulse arrival times, generate a pair of calibration pulses defining an interpolation interval, and process said calibration pulses to produce calibration clock values reflective of the relative spacing in time of said calibration pulses; and interpolate said respective fractional portions within said interpolation interval to produce start and end clock values reflective of said respective fractional portions, said start and end clock values being defined with respect to said calibration pulses; and means for acquiring counts comprising the number of integral said clock periods elapsing between said start and end pulses, said start and end clock values, and said calibration clock values, said means for acquiring counts being connected to said timing interpolation circuitry; wherein said self-calibrating interpolation is performed at least once each time a measurement of the elapsed time is made.
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2. A laser speed detector, comprising:
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a housing having dimensions suitable for being hand-held during operation; a power source positioned within said housing and providing a high voltage output and a low voltage output as required to other components; a laser rangefinder system disposed within said housing, including a laser pulse generator operable to generate a series of laser pulses, and laser light detection means constructed to receive light reflected from a target, said laser rangefinder being constructed to determine the respective times-of-flight of said laser pulses to a target and back to said light detection means; a sighting scope attached to said housing and operably associated with said laser rangefinder such that when a user views a selected target through said sighting scope, said laser pulse generator and said light detector are simultaneously aimed at said selected target; a trigger mounted to said housing to be operable by a user to trigger operation of said speed detector; and control means including a microcontroller having memory means for storing instructions and data, said microcontroller being communicatively interconnected to said power source and said laser rangefinder and said control means being configured to; calculate a plurality of distances to said target from said flight times and the speed of light, each corresponding to a different successive ones of a series of laser pulses; and calculate by a least squares calculation a velocity of said target relative to said observer based on said distances and the elapsed time between the individual said pulses corresponding to said distances. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A laser-type speed detector for determining the relative velocity of a target, comprising:
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a housing; a power source positioned within said housing and providing a high voltage output and a low voltage output; a laser pulse generator connected to receive high voltage from said power source and operable to generate one or more laser pulses; reference pulse means for generating an REF (reference) pulse representative of the time of firing of said laser pulse; light detection means for receiving and detecting light reflected from said target and in response producing an RX (return) pulse; timing analysis circuitry connected to receive said RX pulse and said REF pulse, and operable to produce said count data relating to the elapsed time between said REF and RX pulses, wherein said count data comprise REF count data and RX count data, and wherein said timing analysis circuitry is further constructed to produce self-calibration pulses and to process said self-calibration pulses in the same manner as said REF and RX pulses to produce calibration count values; and control means including a microcontroller having memory means for storing instructions and data, said microcontroller being communicatively interconnected to said power source, said laser pulse generator, and said timing analysis circuitry, wherein said microcontroller is configured to; read said calibration count values; calculate said time-of-flight from said calibration count values, said REF and RX count data, and the speed of light; and compute a detected velocity of said target from said time-of-flight. - View Dependent Claims (13, 14, 15, 16)
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Specification