Location system using ultrasound

Patent metadata

Field	Value
Publication number	US-10114105-B2
Application number	US-201314419207-A
Country	US
Kind code	B2
Filing date	Aug 1, 2013
Priority date	Aug 3, 2012
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A transmitter device transmits an ultrasonic signal encoding a binary identifier. Each bit position in the identifier is associated with a pair of frequencies and with first and second time positions in the signal. The bit value determines which of the pair of frequencies is transmitted at the first time position, with the other being transmitted at the second time position. A receiver device receives the signal. Each bit position of the identifier is decoded based on the strength of the received signal at (a) the first frequency and first time position associated with the particular bit position, (b) the associated first frequency and second time position, (c) the associated second frequency and first time position, and (d) the associated second frequency and second time position. The decoded identifier is used to determine information relating to the position of a mobile one of the devices.

First claim

What is claimed is:

1. A system comprising:
a transmitter device configured to transmit an ultrasonic signal that communicates a binary identifier using an encoding, wherein the encoding is such that each bit position in the identifier is associated with a respective pair of frequencies and with respective first and second time positions in the signal, with the value of the bit position in the identifier determining which frequency of the pair of frequencies is transmitted at the first respective time position in the signal, and with the other frequency of the pair of frequencies being transmitted at the second respective time position in the signal; and
a receiver device comprising an ultrasonic receiver and a processing system, wherein the receiver device is configured to:
receive, with the ultrasonic receiver, said ultrasonic signal that encodes the binary identifier, wherein the encoding is such that each bit position in the identifier is associated with a respective pair of frequencies and with respective first and second time positions in the signal, with the value of the bit position in the identifier determining which frequency of the pair of frequencies is transmitted at the first respective time position in the signal, and with the other frequency of the pair of frequencies being transmitted at the second respective time position in the signal;
use the processing system to determine, for each bit position in the identifier, information relating to the strength of the received signal at (a) the first frequency and first time position, associated with the respective bit position, (b) the first frequency and second time position, associated with the respective bit position, (c) the second frequency and first time position, associated with the respective bit position, and (d) the second frequency and second time position, associated with the respective bit position; and

use the processing system to decode the binary identifier from the received signal by determining a respective value for each bit position in the identifier from said information relating to the strength of the received signal.

2. The system of claim 1 , wherein the transmitter device is a static transmitter station, and wherein the receiver device is a mobile receiver unit.

3. The system of claim 1 , further comprising a position-determining subsystem, wherein the position-determining subsystem is configured to use receipt of the binary identifier by the receiver device to detect proximity between the transmitter device and the receiver device, and thereby to estimate a position of the transmitter device or of the receiver device.

4. The system of claim 1 , wherein the processing system is configured to determine a reliability measure for each bit of the binary identifier in the received signal, and wherein the system further comprises a position-determining subsystem configured to use the decoded binary identifier to determine information relating to the position of the transmitter device or of the receiver device, and to use the reliability measures for all the bits in the identifier when using the decoded binary identifier to determine information relating to the position of the transmitter device or of the receiver device.

5. The system of claim 4 , configured to require a function of the reliability measures for the decoded bits to exceed an inertia threshold value, or to require each bit-reliability measure individually to exceed an inertia threshold value, before the decoded identifier is used to determine a position update for the transmitter device or for the receiver device, when the decoded identifier differs from a preceding decoded identifier.

6. The system of claim 1 , configured not to use a decoded binary identifier to update the position of the transmitter device or of the receiver device when the minimum bit-position received-signal-strength across all the bits of the identifier is less than a predetermined fraction of the average bit-position received-signal-strength across all the bits of the identifier, where the received-signal-strength for a bit position is determined as the larger of (i) the sum of an amplitude value for the first frequency and first time position and an amplitude value for the second frequency and second time position, and (ii) the sum of an amplitude value for the second frequency and first time position and an amplitude value for the first frequency and second time position.

7. The system of claim 1 , comprising a plurality of static transmitter stations, wherein the static transmitter stations are configured to transmit ultrasonic signals substantially simultaneously, and wherein the ultrasonic signals communicate respective binary identifiers according to the aforesaid encoding.

8. The system of claim 7 , wherein the static transmitter stations are configured to transmit their respective ultrasonic signals with the same transmission power as each other.

9. The system of claim 7 , wherein the static transmitter stations are synchronised and wherein the static transmitter stations are configured, for each bit position of their binary identifiers, to transmit at substantially the same time as each other a portion of their respective ultrasonic signals that encodes that bit position of their binary identifiers.

10. The system of claim 7 , comprising two static transmitter stations configured to transmit, at the same time as each other, signal portions encoding at least one bit position of their binary identifiers at which their respective identifiers have the same value as each other, and to transmit, at different times from each other, signal portions encoding at least one other bit position for which their respective identifiers have different values.

11. The system of claim 10 , wherein said two static transmitter stations share a common housing, but have separate respective ultrasonic transducers.

12. The system of claim 7 , wherein the static transmitter stations are configured to transmit zone identifiers and area identifiers within the same ultrasonic signal, and wherein the system further comprises a position-determining subsystem configured to decode a zone identifier from a received signal first and to determine whether the zone identifier has changed from a preceding decoded zone identifier, and to decode the area identifier from the received signal only if the zone identifier has changed.

13. The system of claim 1 , further comprising a position-determining subsystem, located in one or more remote servers and configured to use the decoded binary identifier to determine information relating to the position of the transmitter device or of the receiver device.

14. The system of claim 1 , wherein the receiver device is configured:
to determine whether the decoded binary identifier differs from a previously decoded binary identifier;
to determine whether a reliability criterion for the decoding is satisfied; and
when both determinations are made, to transmit the decoded binary identifier to an external receiver.

15. The system of claim 1 , wherein the transmitter device is a mobile transmitter unit, and the receiver device is a static receiver station.

16. The system of claim 15 , comprising a plurality of mobile transmitter units configured to transmit signals at different times from one another, wherein the system further comprises a position-determining subsystem configured to use (i) a received signal strength for each mobile transmitter unit at one or more static receiver stations, or (ii) time-of-arrival information, or both, to determine information relating to the positions of e

Assignees

• Sonitor Technologies As

Inventors

• Booij Wilfred Edwin
• Olsen Oystein Haug

Classifications

• G01S5/18 Primary

  using ultrasonic, sonic or infrasonic waves · CPC title

• G01S1/75

  Transmitters · CPC title

• G01S1/74

  Details · CPC title