>22. It should be noted that elements in this embodiment similar to the first embodiment are referred to by similar reference numerals, and repeated descriptions thereof are omitted.

In this embodiment, the first portable device 20 includes a first processor 200, a first modulable magnetic source 202, a first memory 204 and a second modulable magnetic source 206. The first modulable magnetic source 202, the first memory 204 and the second modulable magnetic source 206 are electrically connected to the first processor 200.

Similar to the first electronic device mentioned in the first embodiment, the first processor 200 can be configured to control the first modulable magnetic source 202 to generate a first modulated magnetic field M21, and control the second modulable magnetic source 206 to generate a second modulated magnetic field M22.

Specifically, the first modulable magnetic source 202 and the second modulable magnetic source 206 can be configured in different ways, so as to transmit identification information corresponding to the first modulable magnetic source 202 and the second modulable magnetic source 206, and the transmitted identification can be used to identify the first modulable magnetic source 202 and the second modulable magnetic source 206 once received.

In some embodiments, the first processor 200 can control the first modulable magnetic source 202 to generate the first modulated magnetic field M21 with a first modulation mode D21, and control the second modulable magnetic source 206 to generate the second modulated magnetic field M22 with a second modulation mode D22. The first modulation mode D21 and the second modulation mode D22 are similar to the predetermined modulation pattern mentioned in the first embodiment, and each directly or indirectly defines one or more of a frequency, a strength and an orientation of the modulated magnetic field. It should be noted that the first modulation mode is different from the second modulation mode, such that the generated first and second modulated magnetic fields M21 and M22 can be used to identify different magnetic sources.

In some embodiments, the first processor 200 can be configured to determine the first modulation mode D21 according to first predetermined information D23, and determine the second modulation mode D22 according to second predetermined information D24. It should be noted that the first predetermined information D23 and the second predetermined information D24 can be, for example, unique serial numbers corresponding to the first modulable magnetic source 202 and the second modulable magnetic source 206, and can be stored in the first memory 204. The encoding rule mentioned in the first embodiment can be similarly utilized in the present embodiment to determine the first modulation mode D21 and the second modulation mode D22, which can also be stored in the first memory 204.

Referring to FIG. 3, the host device 22 includes a host processor 220, a magnetic sensor 222 and a host memory 224.

In FIGS. 3 and 4, the magnetic sensor 222, which is similar to the magnetic sensor 122 in the first embodiment, can be configured to detect the first modulated magnetic field M21 and the second modulated magnetic field M22. The host processor 220, which is similar to the second processor 120 mentioned in the first embodiment, can be configured to receive the detected first modulated magnetic field M21 to identify the first modulable magnetic source 202, and to the detected second modulated magnetic field M22 to identify the second modulable magnetic source 206.

In detail, in response to receiving the detected first modulated magnetic field M21 and the detected second modulated magnetic field M22 from the magnetic sensor 222, the host processor 220 can decode the detected first modulated magnetic field M21 and the detected second modulated magnetic field M22, by executing a decoding algorithm D25 stored in the host memory 224, to obtain the first predetermined information D23 and the second predetermined information D24.

Next, the host processor 220 can identify the first modulable magnetic source 202 and the second modulable magnetic source 206 according to a device table D26 stored in the host memory. The device table D26 is a table that defines correspondences between multiple devices and identification information. For example, the first predetermined information D23 and the second predetermined information D24 can be identification information corresponding to the first modulable magnetic source 202 and the second modulable magnetic source 206, therefore, the host processor 220 can obtain devices, such as the first modulable magnetic source 202 and the second modulable magnetic source 206, that respectively correspond to the first predetermined information D23 and the second predetermined information D24 from the device table D26.

On the other hand, the host processor 220 can be further configured to obtain first positioning information of the first modulable magnetic source 202 and second positioning information of the second modulable magnetic source 206, by analyzing the detected first modulated magnetic field M21 and the detected second modulated magnetic field M22. For example, the host processor 220 analyzes the detected first modulated magnetic field M21 to obtain a strength and an orientation of the first modulable magnetic source 202.

Afterward, the strength and the orientation can be compared to Earth's magnetic field (also known as the geomagnetic field), that is, the first positioning information can be obtained by comparing the strength and the orientation of the detected first modulated magnetic field M21 with the strength and the orientation of the geomagnetic field, and so forth, the second positioning information of the second modulable magnetic source 206 can be similarly obtained. The mechanisms mentioned in the present embodiment can be utilized in various applications.

As shown in FIG. 4, the first portable device 20 can be a wearable device, such as a head-mounted display (HMD) device 20A, the first modulable magnetic source 202 and the second modulable magnetic source 206 can be arranged inside a housing of the HMD device 20A in a predetermined arrangement. For example, the first modulable magnetic source 202 and the second modulable magnetic source 206 can be arranged on two opposite inner sides of the housing, respectively.

When a user U1 places the wearable device on a body part of the user, such as placing the HMD device 20A on the head of the user U1, since the first modulable magnetic source 202 and the second modulable magnetic source 206 can be identified and their position information can also be obtained through the magnetic sensor 222, the host processor 220 can be configured to obtain a direction and a position of the body part (e.g., head) according to the first positioning information and the second positioning information. It should be noted that movements of the first modulable magnetic source