Signal evaluation circuit for a motion detector
First Claim
1. A signal evaluation circuit for a motion detector in which an output signal from an infrared sensor has a relatively large direct current component and a small alternating current component, comprising:
- an analog-to-digital converter for digitizing the sensor signal to form a digitized signal;
a digital high-pass filter operatively coupled to the analog-to-digital converter for filtering out the direct current component from the digitized signal; and
an amplifier operatively coupled to the digital high-pass filter for amplifying the alternating current component.
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Accused Products
Abstract
The motion detector generates a sensor signal (SS) which contains a direct current portion and an alternating current portion. The signal evaluation circuit (3) contains means for filtering out the direct current portion, an analogue-to-digital converter (4) and an amplifier for the alternating current portion of the sensor signal. The analogue-to-digital converter (4) is provided for the direct digitizing of the entire sensor signal (SS) and the means for filtering out the direct current portion are formed by a digital high-pass filter (5) connected downstream of the analogue-to-digital converter.
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Citations
17 Claims
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1. A signal evaluation circuit for a motion detector in which an output signal from an infrared sensor has a relatively large direct current component and a small alternating current component, comprising:
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an analog-to-digital converter for digitizing the sensor signal to form a digitized signal; a digital high-pass filter operatively coupled to the analog-to-digital converter for filtering out the direct current component from the digitized signal; and an amplifier operatively coupled to the digital high-pass filter for amplifying the alternating current component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A signal evaluation circuit for a motion detector in which an output signal from a motion sensor has a relatively large direct current component and a small alternating current component, comprising:
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an analog-to-digital converter comprising a sigma-delta structure, for digitizing the sensor signal to form a digitized signal; a digital high-pass filter operatively coupled to the analog-to-digital converter for filtering out the direct current component from the digitized signal; and an amplifier operatively coupled to the digital high-pass filter for amplifying the alternating current component. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification