Method and apparatus for converting a modulated optical signal to an electrical signal with correction for modulation jitter
First Claim
1. A method for converting to an electrical signal a modulated optical signal subject to variation about a predefined modulation frequency, comprising the steps of:
- (a) receiving the optical signal at an optical detector;
(b) producing as an output of said detector an electrical signal corresponding to said optical signal, the amplitude of said electrical signal varying with its frequency;
(c) adjusting the amplitude of said electrical signal in a predefined frequency-dependent manner, inversely to the variation of the amplitude of said electrical signal with frequency of said step (b).
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Abstract
A method for accurately converting to an electrical signal a modulated optical signal, the modulation frequency of which randomly varies in a narrow range about a predefined optimum modulation frequency, includes the steps of receiving the optical signal at an optical detector, producing as an output of the optical detector an electrical signal corresponding to the optical signal, the amplitude of which electrical signal varies with frequency, and modifying the amplitude of the electrical signal, depending on the frequency of the electrical signal, inversely to the variation of the amplitude of the electrical signal with frequency caused by the optical detector.
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Citations
16 Claims
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1. A method for converting to an electrical signal a modulated optical signal subject to variation about a predefined modulation frequency, comprising the steps of:
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(a) receiving the optical signal at an optical detector; (b) producing as an output of said detector an electrical signal corresponding to said optical signal, the amplitude of said electrical signal varying with its frequency; (c) adjusting the amplitude of said electrical signal in a predefined frequency-dependent manner, inversely to the variation of the amplitude of said electrical signal with frequency of said step (b). - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for converting a modulated optical signal subject to variation in its modulation frequency, comprising:
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(a) an optical detector for receiving the optical signal and producing at an output an electrical signal corresponding to the optical signal, the amplitude of the electrical signal varying with the modulation frequency; (b) an electrical circuit coupled to said output of said detector, said electrical circuit adapted to vary the amplitude of an output electrical signal depending on the frequency of an input electrical signal. - View Dependent Claims (7, 8, 9, 10)
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11. A method for obtaining an electrical signal the magnitude of which is representative of a characteristic of a physical body, comprising the steps of:
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(a) irradiating the physical body with an optical signal, modulated at a modulation frequency varying within a narrow range; (b) receiving the optical signal after interaction with the physical body and using a photodetector to convert the optical signal to an electrical signal; and (c) adjusting the amplitude of the electrical signal in a predetermined manner dependent on the frequency of the electrical signal, said predetermined manner being selected to correct for variation of the amplitude of the electrical signal with the frequency of the optical signal. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification