Methods and apparatuses for determining a position of a security tag

1. A security tag, comprising:

a memory;

a magnetic field sensing device configured to:

receive a magnetic signal from a magnetic signal transmitter, wherein the magnetic signal includes a transmitter identification associated with the magnetic signal transmitter; and

determine a strength of the magnetic signal at the security tag; and

a radio frequency identification (RFID) device configured to:

receive a RFID interrogatory signal from a RFID scanner;

transmit a RFID response signal, to the RFID scanner, indicating the strength of the magnetic signal and the transmitter identification.

2. The security tag of claim 1 , wherein the memory is configured to store a value associated with the strength of the magnetic signal.

3. The security tag of claim 1 , wherein a modulation of the magnetic signal indicates the transmitter identification.

4. The security tag of claim 1 , wherein the magnetic signal is an electro-magnetic signal or an acousto-magnetic signal.

5. The security tag of claim 1 , wherein the magnetic device is further configured to:

determine a distance between the security tag and the magnetic signal transmitter based on the strength of the magnetic signal; and

wherein transmitting the RFID response signal comprises transmitting a value associated with the distance to the RFID scanner.

6. A method by a radio frequency identification (RFID) scanner, comprising:

obtaining a transmission strength of a magnetic signal transmitted from a magnetic signal transmitter to a security tag;

transmitting a RFID interrogatory signal to the security tag from the RFID scanner;

receiving a RFID response signal, from the security tag, indicating a reception strength of the magnetic signal received at the security tag and a transmitter identification associated with the magnetic signal transmitter; and

determining a distance between the security tag and the magnetic signal transmitter based on the transmission strength of the magnetic signal and the reception strength of the magnetic signal.

7. The method of claim 6 , wherein determining the distance comprises:

determining a difference between the transmission strength of the magnetic signal and the reception strength of the magnetic signal; and

determining a square root or a cube root of the difference.

8. The method of claim 6 , further comprising;

obtaining a second transmission strength of a second magnetic signal transmitted from a second magnetic signal transmitter to the security tag;

obtaining a third transmission strength of a third magnetic signal transmitted from a third magnetic signal transmitter to the security tag;

receiving a second RFID response signal, from the security tag, indicating a second reception strength of the second magnetic signal received at the security tag;

receiving a third RFID response signal, from the security tag, indicating a third reception strength of the third magnetic signal received at the security tag;

determining a second distance between the security tag and the second magnetic signal transmitter based on the second transmission strength and the second reception strength of the second magnetic signal;

determining a third distance between the security tag and the third magnetic signal transmitter based on the third transmission strength and the third reception strength of the third magnetic signal; and

determining a position of the security tag based on the distance, the second distance, and the third distance.

9. The method of claim 6 , wherein the magnetic signal is an electro-magnetic signal or an acousto-magnetic signal.

10. The method of claim 6 , further comprising:

determining whether the distance smaller than or equal to a threshold distance; and

performing a RFID logic or operation in response to determining that the distance is smaller than or equal to the threshold distance.

11. A method by a radio frequency identification (RFID) system, comprising:

transmitting an interrogatory magnetic signal to a RFID tag;

receiving, from the RFID tag, a response magnetic signal in response to the interrogatory magnetic signal;

determining whether the RFID tag is within a threshold distance based on the response magnetic signal; and

in response to determining that the RFID tag is within the threshold distance:

transmitting an interrogatory RFID signal to the RFID tag; and

receiving, from the RFID tag, a response RFID signal in response to the transmitted interrogatory RFID signal.

12. The method of claim 11 , wherein the response RFID signal includes at least one of merchandise information, tag information, or pricing information.

13. The method of claim 11 , further comprising transmitting an unlocking signal to the RFID tag to unlock the RFID tag from a merchandise item.

14. The method of claim 11 , wherein the interrogatory magnetic signal is an electro-magnetic signal or an acousto-magnetic signal.

15. The method of claim 11 , wherein determining whether the RFID tag is within the threshold distance comprises:

determining a tag distance between the RFID tag and at least a portion of the RFID system based on an amplitude of the response magnetic signal; and

determining whether the tag distance is less than the threshold distance.

16. The method of claim 15 , wherein determining the tag distance comprises determining the tag distance based on a transmission strength of the interrogatory magnetic signal and a reception strength of the interrogatory magnetic signal.

17. The method of claim 15 , wherein determining the tag distance comprises determining the tag distance based on a transmission strength of the response magnetic signal and a reception strength of the response magnetic signal.

18. A radio frequency identification (RFID) system, comprising:

a magnetic signal device configured to:

transmit an interrogatory magnetic signal to a RFID tag; and

receive, from the RFID tag, a response magnetic signal in response to the interrogatory magnetic signal; and

a RFID reader configured to:

determine whether the RFID tag is within a threshold distance based on the response magnetic signal; and

in response to determining that the RFID tag is within the threshold distance:

transmitting an interrogatory RFID signal to the RFID tag; and

receiving, from the RFID tag, a response RFID signal in response to the transmitted interrogatory RFID signal.

19. The RFID system of claim 18 , wherein the response RFID signal includes at least one of merchandise information, tag information, or pricing information.

20. The RFID system of claim 18 , wherein the RFID reader is further configured to transmit an unlocking signal to the RFID tag to unlock the RFID tag from a merchandise item.

21. The RFID system of claim 18 , wherein the interrogatory magnetic signal is an electro-magnetic signal or an acousto-magnetic signal.

22. The RFID system of claim 18 , wherein determining whether the RFID tag is within the threshold distance comprises:

determining a tag distance between the RFID tag and at least a portion of the RFID system based on an amplitude of the response magnetic signal; and

determining whether the tag distance is less than the threshold distance.

23. The RFID system of claim 22 , wherein determining the tag distance comprises determining the tag distance based on a transmission strength of the interrogatory magnetic signal and a reception strength of the interrogatory magnetic signal.

24. The RFID system of claim 22 , wherein determining the tag distance comprises determining the tag distance based on a transmission strength of the response magnetic signal and a reception strength of the response magnetic signal.