US 11,375,468 B2Granted

Method and apparatus for synchronising a location network

AssigneeLocata Corporation Pty Ltd

InventorsDavid Small, Ian Sainsbery

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Abstract

Apparatus and methods are presented for synchronising a slave device signal to a reference timebase, in situations where the slave device lacks knowledge of the propagation delay for signals from the reference device, e.g. if the positions of one or both of the devices are unknown or classified, or the inter-device signal propagation distance is otherwise a-priori unknown. Reference signal propagation delay is determined using an exchange of signals between the devices, with each device using a differencing procedure for eliminating effects of receiver line bias and other hardware delays. In another aspect an exchange of signals between the devices is used to detect a time residual arising from an inaccurate propagation delay estimate. The synchronisation methods can be applied to a plurality of slave devices for providing a synchronised location network. In certain embodiments signals are transmitted wirelessly, while in other embodiments they are transmitted via a fixed line.

Claims16

Dependent claims

A method for synchronising a second signal generated and transmitted by a second device to a timebase of a first device, said method comprising the steps of:

(i) said first device generating and transmitting a first signal comprising first time information indicating the time of transmission of said first signal according to the timebase of said first device;
(ii) said second device:
(a) receiving and interpreting said first signal;
(b) generating and transmitting said second signal comprising second time information indicating the time of transmission of said second signal;
(c) receiving and interpreting said second signal;
(d) calculating a first time difference between said first time information and said second time information;
and
(e) adjusting the generation of said second signal according to said first time difference, thereby adjusting said second signal and said second time information;
(iii) said first device:
(a) receiving and interpreting said first signal and the adjusted second signal;
(b) calculating a second time difference between said first time information and the adjusted second time information;
and
(c) transmitting said second time difference, or a quantity related thereto;
and
(iv) said second device:
(a) receiving said second time difference or the related quantity and obtaining therefrom a measure of the propagation delay of said first signal;
and
(b) adjusting the generation of said second signal according to said measure of said propagation delay,
thereby synchronising said second signal to said timebase.

16 more elements

An apparatus for synchronising a second signal generated and transmitted by a second device to a timebase of a first device, said apparatus comprising:

a first device configured to generate and transmit a first signal comprising first time information indicating the time of transmission of said first signal according to a timebase of said first device;
and
a second device configured to:
receive and interpret said first signal;
generate and transmit a second signal comprising second time information indicating the time of transmission of said second signal;
receive and interpret said second signal;
calculate a first time difference between said first time information and said second time information;
and
adjust the generation of said second signal according to said first time difference, thereby adjusting said second signal and said second time information;
wherein said first device is further configured to:
receive and interpret said first signal and the adjusted second signal;
calculate a second time difference between said first time information and the adjusted second time information;
and
transmit said second time difference, or a quantity related thereto;
and wherein said second device is further configured to:
receive said second time difference or the related quantity and obtain therefrom a measure of the propagation delay of said first signal;
and
adjust the generation of said second signal according to said measure of said propagation delay,
thereby synchronising said second signal to said timebase.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/980,421Filed 14 Mar 2019
Priority: AU 201890084114 Mar 2018
Published: US 2021/0007075 A17 Jan 2021
Granted: 28 Jun 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

H04W 56/0065
Determining timing error of reception due to propagation delay: using measurement of signal travel time
G01S 1/024
Means for monitoring or calibrating: of beacon transmitters
G01S 1/08
Using radio waves: systems for determining direction or position line
G01S 1/24
Using a comparison of transit time of synchronised signals transmitted from non-directional antennas or antenna systems spaced apart, i.e.…: the…