Ambient light sensitive activator
First Claim
1. A light sensitive activator for providing a signal in response to passage of an object of a given shape through a defined airspace, said activator comprising:
- sensor means exposed to ambient light by way of said airspace;
data acquisition means for providing a detection signal representing an amount of ambient light incident upon said sensor means, wherein the detection signal waveform is a function of the shape of the object as the object passes through said airspace; and
means for ascertaining passage of said object of said given shape by receiving said detection signal and responding to a peak value therein to provide an activation signal.
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Accused Products
Abstract
An activation signal is generated when an aircraft passes directly overhead and may be employed to record aircraft noise levels or to trigger a zenith camera for producing a photograph of the aircraft useful in determining aircraft position. When used in connection with a second instrument located at a fixed distance from the first and along the path of the aircraft, aircraft ground speed may be determined. Ambient light, normally passing through an optically defined airspace and thence incident upon light sensors, is partially blocked when an object such as an aircraft is present. A signal proportional to the change in ambient light incident upon the sensors and a function of the size and shape of the aircraft is used to sense the passage of a wing section. Upon detection of the wing section an activation signal is generated.
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Citations
15 Claims
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1. A light sensitive activator for providing a signal in response to passage of an object of a given shape through a defined airspace, said activator comprising:
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sensor means exposed to ambient light by way of said airspace; data acquisition means for providing a detection signal representing an amount of ambient light incident upon said sensor means, wherein the detection signal waveform is a function of the shape of the object as the object passes through said airspace; and means for ascertaining passage of said object of said given shape by receiving said detection signal and responding to a peak value therein to provide an activation signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A light sensitive activator for providing an activation signal, said activator comprising:
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data acquisition means including photoconductive elements for measuring ambient light incident thereon, and light shielding means for defining an optical airspace through which ambient light travels to reach the photoconductive elements, said data acquisition means producing a detection signal representing an amount of ambient light incident upon the photoconductive elements and thereby responding to blockage of ambient light caused by the presence of an object in the airspace; data sampling means for capturing a peak value in the detection signal and providing a scaled peak signal, the scaled peak signal being a fixed percentage of the captured peak value; and comparator means for comparing the scaled peak signal to the detection signal and providing the activation signal when the detection signal is less than the scaled peak signal. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of providing an activation signal in response to the passage of an airplane, the method comprising:
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defining an optical airspace as the space through which ambient light passes to reach light sensor means; generating a detection signal representing an amount of ambient light incident upon light sensor means and thereby responding to blockage of ambient light caused by the presence of an airplane in the airspace; storing a peak value of the detection signal; and comparing a function of the peak value to the detection signal and providing the activation signal in response to said comparison.
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Specification