RADIO ARRIVAL DIRECTION ESTIMATION DEVICE AND RADIO ARRIVAL DIRECTION ESTIMATION METHOD

• US 20110133988A1
• Filed: 09/04/2009
• Published: 06/09/2011
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Fukagawa, Takashi, Mukai, Hirohito, Nakagawa, Yoichi
• Granted Patent: US 8,400,357 B2
• Time in Patent Office: Days
• US Class Current: 342/442
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems

Abstract

A radio arrival direction estimation device that accurately estimates the arrival direction of radio waves from a desired tag, even when there are multiple antennas disposed at short intervals. When ID detection timing is provided from a timing detector (114) to a switch (201), relative amplitude/phase data related to the tag ID digital value “1” or “0” is obtained by an arrival direction estimation unit (125). One relative amplitude/phase datum is formed for each unit cycle in a first adder (202), which adds the relative amplitude/phase datum related to the tag ID digital value “1” to each element in a matrix, and a second adder (203), which adds the relative amplitude/phase datum related to the tag ID digital value “0” to each element in a matrix. An OOK signal causes an arithmetic unit (204) to subtract the relative amplitude/phase data produced by the second adder (203) from the relative amplitude/phase data produced by the first adder (202), and extract the phase of a signal corresponding to the phase of the digital value “1.”

Claims

1. A radio arrival direction estimating apparatus comprising:

an ultra wide band antenna that receives a signal transmitted from a tag;

a tag identification detecting section that detects a tag identification from the signal received by the ultra wide band antenna;

a timing detecting section that associates and detects a timing the tag identification is detected and a sample timing of an identification bit sequence of the tag identification;

an array antenna that is formed with a plurality of antenna elements that receive the signal transmitted from the tag;

a calculating section that calculates relative amplitude phase information to indicate a relative amplitude and phase difference between the plurality of antennas, from the signal received by the array antenna; and

an arrival direction estimating section that estimates an arrival direction of the signal transmitted from the tag, using a timing associated with the sample timing of the identification bit sequence and the relative amplitude phase information.

2. The radio arrival direction estimating apparatus according to claim 1, wherein the arrival direction estimating section comprises:

a first addition section that adds relative amplitude phase information generated using a plurality of items of sample data sampled at a timing associated with bit 1 of the identification bit sequence;

a second addition section that adds relative amplitude phase information generated using a plurality of items of sample data sampled at a timing associated with bit 0 of the identification bit sequence;

an operating section that subtracts the relative amplitude phase information added in the second addition section from the relative amplitude phase information added in the first addition section;

a Fourier beam sweep section calculates an angle spectrum by sweeping a Fourier beam using a subtraction result in the operating section; and

a peak detecting section that detects a peak of the angle spectrum.

3. The radio arrival direction estimating apparatus according to claim 1, wherein the plurality of antenna elements receive a narrower hand signal than the signal received in the ultra wide band antenna.

4. The radio arrival direction estimating apparatus according to claim 1, wherein the calculating section calculates a correlation matrix or covariance matrix from the received signal, as the relative amplitude phase information.

5. The radio arrival direction estimating apparatus according to claim 1, wherein the array antenna comprises:

a plurality of first antenna elements having a first center frequency; and

a plurality of second antenna elements having a second center frequency different from the first center frequency.

6. The radio arrival direction estimating apparatus according to claim 5, further comprising a switching and combining section that switches or combines reception signals received in the plurality of first antenna elements and reception signals received in the plurality of second antenna elements.

7. The radio arrival direction estimating apparatus according to claim 1, wherein the plurality of antenna elements are comprised of first to third antenna elements placed in vertices of a regular triangle and a fourth antenna element placed in a centroid of the regular triangle.

8. The radio arrival direction estimating apparatus according to claim 1, wherein:

the plurality of antenna elements are comprised of first to third antenna elements placed in vertices of a regular triangle; and

the ultra wide band antenna is placed in a centroid of the regular triangle.

9. A radio arrival direction estimating method comprising:

a tag identification detecting step of detecting a tag identification from a signal which is transmitted from a tag and received by an ultra wide band antenna;

a timing detecting step of associating and detecting a timing the tag identification is detected and a sample timing of an identification bit sequence of the tag identification;

a calculating step of calculating relative amplitude phase information to indicate a relative amplitude and phase difference between the plurality of antennas, from the signal which is transmitted from the tag and received by an array antenna formed with a plurality of antenna elements; and

an arrival direction estimating step of estimating an arrival direction of the signal transmitted from the tag, using a timing associated with the sample timing of the identification bit sequence and the relative amplitude phase information.