System and methods for dynamic range extension using variable length integration time sampling
First Claim
1. A method of sampling a photo-detector signal, the method comprising:
- performing a series of integrations of the photo-detector signal wherein the series comprises alternating long and short integration intervals; and
forming a plurality of overlapping sample sets wherein each sample set comprises integrations performed during at least one long interval to yield a first signal value and at least one short interval to yield a second signal value and wherein each sample set overlaps with its neighboring sample set by at least one of the long or short intervals.
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Abstract
A photo-detector generated signal is measured as a sample set comprising a long signal and a short signal. The short signal is scaled to the value of the long signal if the long signal exceeds a dynamic range associated with the photo detector. In one embodiment, the short signal is obtained during a short time interval that is at the approximate middle of a long time interval such that the short and long intervals share a common median time value. Given such symmetry, an approximately linear signal yields a proportionality parameter between the long and short signals thereby allowing the short signal to be scaled. The proportionality parameter facilitates determination of an integration independent component of the photo detector signal that should be removed from the measured long and short signals before scaling. A plurality of sample sets can also be processed such that each sample set overlaps with its neighboring sample set, thereby increasing the effective number of sample sets.
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Citations
8 Claims
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1. A method of sampling a photo-detector signal, the method comprising:
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performing a series of integrations of the photo-detector signal wherein the series comprises alternating long and short integration intervals; and forming a plurality of overlapping sample sets wherein each sample set comprises integrations performed during at least one long interval to yield a first signal value and at least one short interval to yield a second signal value and wherein each sample set overlaps with its neighboring sample set by at least one of the long or short intervals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification