SYSTEM AND METHOD OF TIME OF FLIGHT DETECTION

摘要

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.

主权项

1. An apparatus for determining a distance based on a transmitted signal, comprising:
a storage device providing a first set of signal values representing time-ordered noise-less signal values of the transmitted signal, the first set of signal values being divided into sections, each section being associated according to a predetermined criterion with one of a plurality of categories, and each section having a predetermined number of signal values with each signal value being associated with a sample index representing a temporal position of the signal value in time; a signal interface for receiving a second set of signal values representing samples of a received signal, each of the signal values in the second set of signal values being assigned a category and a sample index based on a predetermined alignment in time with the signal values of the first set of signal values, wherein each signal value in the second set of signal value is assigned the same category and sample index as the corresponding signal value in the first set of signal values to which the signal value in the second set of signal values is aligned; a set of accumulators each being associated with a corresponding one of the categories and a corresponding sample index, each accumulator being configured to sum a subset of signal values selected from the second set of signal values, the subset of signal values being signal values that are assigned to corresponding category and sample index; and an arithmetic unit configured to compute one or more convolution of the transmitted signal and the received signal 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.