Positioning of mobile wireless terminal

• US 7,319,428 B2
• Filed: 10/18/2006
• Issued: 01/15/2008
• Est. Priority Date: 04/18/2002
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yamada, Isamu, Ninomiya, Teruhisa
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Mull; Fred H.
• Application Number:
  US11/582,376
• Publication Number:
  US 20070035445A1
• Time in Patent Office: 454 Days
• Field of Search: 342/442, 342/457, 342463-495
• US Class Current: 342/442
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/08 Position of single direction-finder fixed by determining direction of a plurality of spaced sources of known location

Abstract

A wireless apparatus for determining a phase difference of a received RF signal, and method. The apparatus includes antennas displaced from each other by a predetermined distance for receiving an RF signal. The apparatus also includes an exclusive OR (EXOR) circuit comparing binary signals derived from the received RF signal that are associated with respective antennas. An absolute phase difference is based on a pulse width of the comparison.

Claims

1. A wireless apparatus for determining a phase difference of a received RF signal, comprising:

first and second antennas displaced from each other by a predetermined distance for receiving an RF signal;

an exclusive OR (EXOR) circuit comparing two binary signals derived from the received RF signal that are associated with said first and second antennas respectively, wherein an absolute phase difference is based on a pulse width of the comparison; and

a processor for detecting source identification included in said received RF signal.

2. The apparatus according to claim 1, wherein the apparatus is operable in accordance with a Bluetooth standard.

3. The apparatus according to claim 1, wherein the apparatus is operable in accordance with a wireless LAN standard (IEEE 802.11).

4. The apparatus according to claim 1, wherein the wireless apparatus is for determining a phase difference of a received RF signal for estimating an incident angular direction of the RF signal, and for use in a system for estimating a position of a wireless terminal based on the incident angular direction of the RF signal.

5. The apparatus according to claim 1, wherein the processor is for estimating the incident angular direction based on the absolute phase difference and for detecting source identification included in said received RF signal.

6. A method for determining a phase difference based on received RF signals associated with first and second antennas respectively, comprising:

producing a plurality of binary signals based on the received RF signals; and

exclusive ORing at least two of the binary signals; and

detecting source identification included in said received RF signals.

7. The method according to claim 6, wherein the producing the plurality of binary signals comprises:

latching a first signal at a rising edge of a second signal; and

comparing levels of the first and the second signals.

8. The method according to claim 6, wherein the method is for determining a phase difference of a received RF signal for estimating an incident angular direction of the RF signal, and for use in a system for estimating a position of a wireless terminal based on the incident angular direction of the RF signal.

9. The method according to claim 6, further comprising estimating the incident angular direction based on the absolute phase difference.