System and method of time of flight detection
First Claim
1. An apparatus for determining a distance based on a transmitted signal, comprising:
- a storage device providing a first set of signal values of the transmitted signal, the first set of signal values being divided into sections, each section being assigned one of a plurality of categories, and each section being identified by a sample index corresponding to a position of the signal value in time;
a signal interface for receiving a second set of signal values representing, samples of a received signal, the signal interface assigning to each of second set of signal values one of the categories and a sample index based on a predetermined alignment in time between the first and second sets of signal values;
a set of accumulators each being associated with a corresponding one of the categories and a corresponding sample index, wherein each accumulator sums a subset of the second set of signal values corresponding to the category and the sample index of the accumulator; and
an arithmetic unit for computing one or more convolutions using the first set of signal values and the sums in the accumulators under one or more predetermined offsets in time relative to the predetermined alignment.
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Accused Products
Abstract
A position-determining apparatus, such as a GPS receiver, determines the position of the mobile device based on the time of flight of a transmitted probe signal using a method in which sections of the received signal is classified into two or more categories and accumulated according to categories before being used to compute the convolutions familiar in the context of a matched filter. Using the method of the present invention to compute the convolutions, and optionally applying additional time-saving techniques described herein, a position determination is achieved using a number of arithmetic operations that is significantly reduced from that required in prior art methods to compute the convolutions. The reduced number of arithmetic operations can reduce significantly the power consumption required of a device carrying out a method of the present invention, and thereby realizing a significant advantage.
7 Citations
32 Claims
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1. An apparatus for determining a distance based on a transmitted signal, comprising:
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a storage device providing a first set of signal values of the transmitted signal, the first set of signal values being divided into sections, each section being assigned one of a plurality of categories, and each section being identified by a sample index corresponding to a position of the signal value in time; a signal interface for receiving a second set of signal values representing, samples of a received signal, the signal interface assigning to each of second set of signal values one of the categories and a sample index based on a predetermined alignment in time between the first and second sets of signal values; a set of accumulators each being associated with a corresponding one of the categories and a corresponding sample index, wherein each accumulator sums a subset of the second set of signal values corresponding to the category and the sample index of the accumulator; and an arithmetic unit for computing one or more convolutions using the first set of signal values and the sums in the accumulators under one or more predetermined offsets in time relative to the predetermined alignment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification