Methods for Synchronizing Multiple Devices and Determining Location Based on the Synchronized Devices

• US 20180302869A1
• Filed: 11/09/2016
• Published: 10/18/2018
• Est. Priority Date: 11/09/2015
• Status: Active Grant

• Current Assignee: WISER Systems, Inc.
• Original Assignee: WISER Systems, Inc.
• Inventors: Hollar, Seth Edward-Austin
• Granted Patent: US 10,462,762 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 5/00 Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using active systems G01S13/00, G01S15/00, G01S17/00
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/0263 by combining or switching between positions derived from two or more separate positioning systems
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04H 20/18 Arrangements for synchronising broadcast or distribution via plural systems
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0025 synchronizing potentially movable access points
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time
• CPC Class Codes: H04W 56/007 Open loop measurement

Abstract

Methods for synchronizing multiple transceivers to a single master clock are provided including broadcasting a message from a master device, the broadcasted message including a device identification number identifying the master device to at least one known device within range of the master device; receiving the message at the at least one other known device and recording a time of arrival (T_arrival-kd) at the at least one other known device; repeatedly broadcasting and receiving messages and recording associated times of arrival at the at least one other known device; and applying a fit curve to the recorded arrival times to estimate a time of an event. Related devices and systems are also provided.

Claims

1. A method for synchronizing multiple transceivers to a single master clock, the method comprising:

broadcasting a message from a master device, the broadcasted message including a device identification number identifying the master device to at least one known device within range of the master device;

receiving the message at the at least one other known device and recording a time of arrival (T_arrival-kd) at the at least one other known device;

repeatedly broadcasting and receiving messages and recording associated times of arrival at the at least one other known device; and

applying a fit curve to the recorded arrival times to estimate a time of an event.

2. The method of claim 1, wherein the fit curve is applied to two recorded arrival times.

3. The method of claim 1, wherein the fit curve is applied to more than two arrival times.

4. The method of claim 1, wherein the broadcast message includes a time of transmission (T_depart-md).

5. The method of claim 1, wherein both the master device and at least one known device are radio frequency devices configured to send data at a precise time and record a timestamp of received data within a certain degree of precision.

6. The method of claim 1, further comprising:

rebroadcasting the message from the at least one known device, the message including the transmitted time stamp in the master device time units; and

receiving, at a device that is out of RF range of the master device, such that the device that is out of range is synchronized to the master device even when out of RF range using the at least one known device as an intermediate master broadcaster.

7. The method of claim 6, further comprising:

rebroadcasting the message including the transmitted time stamp in master device time units from device that is out of RF range;

receiving the rebroadcasted message at a second device that is out of RF range of the master device; and

synchronizing the second device that is out of RF range by using the device that is out of RF range as an intermediate master broadcaster.

8. The method of claim 1, further comprising:

receiving a broadcast time synchronization signal at the at least one known device from a plurality of master devices; and

applying a weighting algorithm to the plurality of signals to determine an arrival time of the message.

9. The method of claim 8, wherein applying a weighting algorithm comprises averaging.

10. A known device in a network including a plurality of known devices and a master device, the known device comprising:

a receiver configured to receive a broadcast message from a master device that is broadcast to the plurality of known devices within range of the master device, the broadcast message including a device identification number identifying the master device; and

a processor configured to;

record a time of arrival (T_arrival-kd) of the broadcast message at the known device, wherein the receiver receives a plurality of broadcast messages and the processor records a time of arrival for each of the plurality of broadcast messages; and

apply a fit curve to the recorded arrival times to estimate a time of an event.

11. The device of claim 10, wherein the processor is configured to apply the fit curve to two recorded arrival times.

12. The device of claim 10, wherein the processor is configured to apply the fit curve to more than two arrival times.

13. The device of claim 10, wherein the broadcast message includes a time of transmission (T_depart-md).

14. The device of claim 10, wherein both the master device and the plurality of known devices are radio frequency devices configured to send data at a precise time and record a timestamp of received data within a certain degree of precision.

15. The device of claim 10, wherein the device further comprises a transmitter configured to rebroadcast the message from the known device, the message including the transmitted time stamp in the master device time units, to a device that is out of RF range of the master device, such that the device that is out of range is synchronized to the master device even when out of RF range using the known device as an intermediate master broadcaster.

16. The device of claim 10:

wherein the receiver is further configured to receive a broadcast time synchronization signal from a plurality of master devices; and

wherein the processor is configured to apply a weighting algorithm to the plurality of signals to determine an arrival time of the message.

17. A system including a plurality of devices synchronized to a single master clock, the system comprising:

a plurality of known devices including a processor; and

a master device configured to broadcast a message, the broadcasted message including a device identification number identifying the master device to at least one of the plurality of known devices within range of the master device;

wherein the at least one of the plurality of known devices receives the broadcasted message and records a time of arrival (T_arrival-kd);

wherein the master device is configured to repeatedly broadcast messages; and

wherein the at least one of the plurality of known devices is configured to receive the messages and record associated times of arrival and apply a fit curve to the recorded arrival times to estimate a time of an event.

18. The system of claim 17, wherein the master device and the plurality of known devices are radio frequency devices configured to send data at a precise time and record a timestamp of received data within a certain degree of precision.

19. The system of claim 17, wherein the plurality of known devices are configured to

receive a broadcast time synchronization signal from a plurality of master devices apply a weighting algorithm to the plurality of signals to determine an arrival time of the message.