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1. WO2020114917 - A METHOD FOR DEVICE SYNCHRONIZATION

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[ EN ]

CLAIMS:

1. A method for synchronizing a first device (100) and a second device, the first device and the second device being connectable via a wireless link, the method comprising:

generating (202), at the first device, a synchronization signal comprising a sequence of signals, wherein each of the signals in the sequence has a first frequency;

transmitting (204) the sequence of signals from the first device to the second device;

performing (206), at the second device, signal processing of the sequence of signals to determine relative phase information of each of the signals in the sequence; and synchronizing (208), based on the determined relative phase information, the first device and the second device by correcting phase offset of subsequent individual signals transmitted from the first device to the second device.

2. The method according to claim 1, wherein the first device (100) comprises a first transmitter coil (110), a second transmitter coil (120), and a third transmitter coil (130), and wherein transmitting (204) the sequence of signals comprises:

transmitting, from the first transmitter coil, the synchronization signal to the second device (200) as a first signal in the sequence;

transmitting, from the second transmitter coil, the synchronization signal to the second device as a second signal in the sequence; and

transmitting, from the third transmitter coil, the synchronization signal to the second device as a third signal in the sequence.

3. The method according to claim 1 or claim 2, further comprising changing from a synchronization mode in which signal processing of the sequence of signals is performed to a normal mode in which one or more subsequent individual signals are transmitted from the first device (100) to the second device (200).

4. The method according to claim 3, further comprising comparing, in the normal mode, a signal strength of the at least one subsequent individual signals with a predetermined threshold, and changing from the normal mode to the synchronization mode if the signal strength of at least one of the subsequent individual signals is lower than the predetermined threshold.

5. The method according to claim 3 or claim 4, further comprising:

transmitting, in the normal mode, a position signal from each of the first transmitter coil (110), the second transmitter coil (120), and the third transmitter coil (130), wherein the respective position signals from each of the transmitter coils have different frequencies, and

wherein synchronizing the first device (100) and the second device (200) comprises correcting, at the second device, phase offset of each of the transmitted position signals based on the determined relative phase information,

wherein the method further comprises determining, at the second device, a position of the first device relative to the second device based on at least one of the transmitted position signals with corrected phase offsets.

6. The method according to claim 5, wherein correcting phase offset of each of the transmitted position signals comprises determining the phase offset as one of 0° and -180° based on the determined relative phase information.

7. The method according to claim 5 or claim 6, wherein the first device (100) further comprises a functional component (150) located at a predetermined distance from the first to third transmitter coils (110, 120, 130), wherein determining a position of the first device relative to the second device (200) further comprises:

performing signal processing of the position signals to obtain a first position and a second position, wherein one of the first position and the second position corresponds to a hemisphere in which the functional component is located with respect to the first to third transmitter coils;

determining which of the first position and the second position corresponds to the hemisphere in which the functional component is located based on the predetermined distance between the functional component and the first to third transmitter coils; and

selecting the position that corresponds to the hemisphere in which the functional component is located as the correct position of the first device relative to the second device.

8. The method according to any one of claims 2 to 7, wherein performing (206) signal processing of the sequence of signals comprises:

generating a reference signal at the second device (200);

selecting one of the first transmitter coil (110), the second transmitter coil (120), and the third transmitter coil (130) of the first device;

determining a phase offset associated with the selected transmitter coil based on the signal in the sequence transmitted by the selected transmitter coil and the generated reference signal; and

determining, for each of the two other transmitter coils, a phase offset associated with the transmitter coil, wherein determination of the phase offset is based on: the determined phase offset associated with the selected transmitter coil and a phase shift between the signal transmitted from the respective transmitter coil in the sequence and the generated reference signal,

wherein synchronizing the first device and the second device comprises:

synchronizing the phase difference between the first device and the second device based on the determined phase offsets associated with the first to third transmitted coils.

9. The method according to claim 8, wherein the selected transmitter coil is the first transmitter coil (110), and determining the phase offset for the second transmitter coil (120) is performed before determining the phase offset for the third transmitter coil (130).

10. The method according to claim 8 or claim 9, wherein the second device (200) comprises a first receiver coil (210), a second receiver coil (220), and a third receiver coil (230), each of the first to third receiver coils being configured to receive each of the signals in the sequence transmitted from the first device (100), and wherein determining a phase offset associated with a respective transmitter coil comprises:

determining the signal strength of the respective transmitted signal received at each the first receiver coil, the second receiver coil, and the third receiver coil;

selecting one of the first receiver coil, the second receiver coil, and the third receiver coil which corresponds the largest received signal strength; and

determining the phase offset associated with the respective transmitter coil based on the respective transmitter signal received at the selected receiver coil.

11. The method according to any one of claims 2 to 10 , further comprising transmitting a notification from the second device (200) to the first device (100) upon receiving each of the first signal, the second signal, and the third signal.

12. The method according to any one of the preceding claims, further comprising comparing a signal strength of at least one of the signals in the sequence with a

predetermined threshold, wherein the step of synchronizing (208) the first device (100) and the second device (200) is only performed if the signal strength of at least one of the signals in the sequence is higher than the predetermined threshold.

13. A system (10) comprising a first device (100) and a second device (200), the first device and the second device being connectable via a wireless link,

wherein the first device comprises a first control unit (140) configured to: generate a synchronization signal comprising a sequence of signals, wherein each of the signals in the sequence has a first frequency; and

transmit the sequence of signals to the second device, and

wherein the second device comprises a second control unit (240) configured to:

perform signal processing of the sequence of signals to determine relative phase information of each of the signals in the sequence; and

synchronize, based on the determined relative phase information, the first device and the second device by correcting phase offset of subsequent individual signals transmitted from the first device.

14. The system according to claim 13, wherein the second device (200) comprises a first receiver coil (210), a second receiver coil (220), and a third receiver coil (230), and wherein each of the first to third receiver coils is configured to receive each of the signals in the sequence transmitted from the first device.

15. The system according to claim 13 or claim 14, wherein the first device (100) is a personal care device and the second device (200) is a sensor device, and wherein the sensor device is configured to be placed at a predetermined location with respect to a user.