Apparatus for generating a signal providing information regarding a radiating source, especially an infrared source
First Claim
1. An apparatus for generating a deviation signal and a presence signal, wherein said deviation signal represents a deviation of an optical axis of an optical means from a line connecting said optical means with the center of a distant radiation source which is imaged by said optical means onto its image plane, and wherein said presence signal represents an information whether said radiation source is located at all within a range of vision of said optical means, said apparatus comprising an oscillating chopper disk being located in said image plane of said optical means and having a diameter equal to that of the image of said radiation source and sensor means for receiving all the radiation components passing periodically past the edges of said oscillating chopper disk and for producing therefrom a periodic analog sensor signal, drive means for driving said chopper disk, pick-up means arranged for producing a periodic analog chopper signal, an analog-to-digital converter connected to receive said analog sensor signal for converting said analog sensor signal into a digitized sensor signal, a phase-locked-loop circuit including a phase detector having a first input for receiving said periodic analog chopper signal for providing a phase control signal, control amplifier means connected to an output of said phase detector for integrating said phase control signal, an oscillator connected to said control amplifier means for producing start impulses, means connecting said oscillator to a start input of said analog-to-digital converter for repeatedly starting a sampling and digitizing of said analog sensor signal, mode-M counter means having an input connected to said oscillator and an output connected to a second input of said phase detector thereby providing a closed loop phase control circuit, said mode-M counter means counting up to a preselected number M and, upon reaching the count of M, providing phase reference carry signals to said second input of said phase detector, fast Fourier transformation processing means having a first input connected to said analog-to-digital converter for receiving said digitized sensor signal, and means connecting a second input of said fast Fourier transformation processing means to said mode-M counter means for receiving counted values having the same frequency or rhythm as said start impulses and being continuously numbered between two neighboring phase reference carry signals, whereby said fast Fourier transformation processing means produce said deviation signal and said presence signal.
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Accused Products
Abstract
Information regarding an object, especially brightness information, is obned by scanning the object with an optical scanner, especially an infrared scanner to provide a respective analog signal. The analog signal is produced by passing the received radiation past a chopper disk onto a detector through a secondary optical assembly. The output signal of the detector is digitized and supplied to a fast Fourier transformation processor which also receives a counting signal derived from the oscillation of the chopper disk. The system may be used, for example, for obtaining deviation and/or presence signals regarding the orientation of an earth satellite relative to the center of the earth.
31 Citations
9 Claims
- 1. An apparatus for generating a deviation signal and a presence signal, wherein said deviation signal represents a deviation of an optical axis of an optical means from a line connecting said optical means with the center of a distant radiation source which is imaged by said optical means onto its image plane, and wherein said presence signal represents an information whether said radiation source is located at all within a range of vision of said optical means, said apparatus comprising an oscillating chopper disk being located in said image plane of said optical means and having a diameter equal to that of the image of said radiation source and sensor means for receiving all the radiation components passing periodically past the edges of said oscillating chopper disk and for producing therefrom a periodic analog sensor signal, drive means for driving said chopper disk, pick-up means arranged for producing a periodic analog chopper signal, an analog-to-digital converter connected to receive said analog sensor signal for converting said analog sensor signal into a digitized sensor signal, a phase-locked-loop circuit including a phase detector having a first input for receiving said periodic analog chopper signal for providing a phase control signal, control amplifier means connected to an output of said phase detector for integrating said phase control signal, an oscillator connected to said control amplifier means for producing start impulses, means connecting said oscillator to a start input of said analog-to-digital converter for repeatedly starting a sampling and digitizing of said analog sensor signal, mode-M counter means having an input connected to said oscillator and an output connected to a second input of said phase detector thereby providing a closed loop phase control circuit, said mode-M counter means counting up to a preselected number M and, upon reaching the count of M, providing phase reference carry signals to said second input of said phase detector, fast Fourier transformation processing means having a first input connected to said analog-to-digital converter for receiving said digitized sensor signal, and means connecting a second input of said fast Fourier transformation processing means to said mode-M counter means for receiving counted values having the same frequency or rhythm as said start impulses and being continuously numbered between two neighboring phase reference carry signals, whereby said fast Fourier transformation processing means produce said deviation signal and said presence signal.
Specification