Method and system for demodulating a digital pulse recognition signal in a light based positioning system using a Fourier transform
First Claim
1. A method for demodulating a modulated light signal in a light based positioning system, the method comprising:
- receiving a modulated light signal at a device, wherein the modulated light signal transmits an arbitrary identifier of a light source;
recording the modulated light signal using a rolling shutter image sensor to create a raw image having alternating spaced apart stripes;
subtracting background information from the raw image to create an isolated image;
taking a Fourier transform of an image representative of the isolated image to calculate a Fourier transformed signal; and
determining the arbitrary identifier of the light source based on the Fourier transformed signal, wherein determining the arbitrary identifier of the light source comprises;
applying a filter to the Fourier transformed signal to create a filtered Fourier transformed signal;
removing a DC component of filtered Fourier Transformed signal to create a processed signal; and
selecting a peak frequency in the processed signal as the arbitrary identifier.
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Abstract
In one aspect, the present disclosure relates to a method for demodulating a modulated light signal in a light based positioning system. In some embodiments, the method includes receiving a modulated light signal at a device, the modulated light signal transmitting an arbitrary identifier of a light source, recording the modulated light signal using a rolling shutter image sensor to create a raw image having alternating spaced apart stripes, subtracting background information from the raw image to create an isolated image, taking a Fourier transform of an image representative of the isolated image to calculate a Fourier transformed signal, and determining the arbitrary identifier of the light source based on the Fourier transformed signal.
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Citations
14 Claims
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1. A method for demodulating a modulated light signal in a light based positioning system, the method comprising:
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receiving a modulated light signal at a device, wherein the modulated light signal transmits an arbitrary identifier of a light source; recording the modulated light signal using a rolling shutter image sensor to create a raw image having alternating spaced apart stripes; subtracting background information from the raw image to create an isolated image; taking a Fourier transform of an image representative of the isolated image to calculate a Fourier transformed signal; and determining the arbitrary identifier of the light source based on the Fourier transformed signal, wherein determining the arbitrary identifier of the light source comprises; applying a filter to the Fourier transformed signal to create a filtered Fourier transformed signal; removing a DC component of filtered Fourier Transformed signal to create a processed signal; and selecting a peak frequency in the processed signal as the arbitrary identifier. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An image detection apparatus for demodulating a modulated light signal in a light based positioning system, the image detection apparatus comprising:
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an imaging sensor configured to receive a modulated light signal transmitting an arbitrary identifier of a light source and record the modulated light signal using a rolling shutter image sensor; and a processor in communication with the imaging sensor configured to receive the recorded modulated light signal, create a raw image having alternating spaced apart stripes based on the recorded modulated light signal, subtract background information from the raw image to create an isolated image, take a Fourier transform of an image representative of the isolated image to calculate a Fourier transformed signal, and determine the arbitrary identifier of the light source based on the Fourier transformed signal, wherein the processor is configured to determine the arbitrary identifier of the light source by applying a filter to the Fourier transformed signal to create a filtered Fourier transformed signal, removing a DC component of filtered Fourier Transformed signal to create a processed signal, and selecting a peak frequency in the processed signal as the arbitrary identifier. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification