| CPC G01S 1/0428 (2019.08) [G01R 23/165 (2013.01); G01S 1/045 (2013.01); G01S 1/725 (2013.01); G01S 1/763 (2013.01); G01S 5/30 (2013.01); H04B 1/7136 (2013.01); H04W 16/14 (2013.01); H04W 64/006 (2013.01); H04B 2001/71367 (2013.01)] | 20 Claims |

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1. A method for determining of a position of a receiver within a space, the method comprising:
providing a plurality of beacon devices at different locations within said space;
transmitting a beacon signal from each of the beacon devices, each beacon signal having a unique information component and a unique frequency pattern within an operating frequency range, each beacon signal being distinguishable from the beacon signals transmitted from any other of the beacon devices based on a combination of its unique information component and its unique frequency pattern;
receiving acoustic frequency signals at the receiver; and
determining the position within the space of the receiver based on a location of each of the beacon devices of a subset of at least three of the plurality of differently located beacon devices, said determining comprising:
filtering the received acoustic frequency signals by the frequencies of the frequency pattern for each beacon signal transmitted from said working subset to generate filtered signals;
carrying out a correlation of each filtered signal with a version of the information component of the corresponding beacon signal;
identifying a correlation peak from each correlation, the correlation peaks providing time-delay information of each beacon signal; and
applying multilateration to determine the position of the receiver based on the location of each beacon device of the working subset of beacon devices and the time-delay information of the beacon signals.
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