Position detecting system, responder and interrogator, wireless communication system, position detecting method, position detecting program, and information recording medium

• US 8,284,027 B2
• Filed: 09/18/2006
• Issued: 10/09/2012
• Est. Priority Date: 03/17/2004
• Status: Expired due to Fees

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Taki, Kazunari, Ohashi, Tsuyoshi, Nagai, Takuya
• Primary Examiner(s): BROWN, VERNAL U
• Application Number:
  US11/532,649
• Publication Number:
  US 20070018792A1
• Time in Patent Office: 2,213 Days
• Field of Search: 340/10.1, 340/572.1, 340/505, 342/51, 342/50
• US Class Current: 340/10.1
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: H04B 1/7163 using impulse radio

Abstract

There is provided a radio communication system capable of distinguishing objects from one another while taking advantage of the low power consumption and distance measurement ability of the radio communication of the UWB method. A radio tag TGn includes: a characteristic impedance unit (3) for generating a response signal by using a pulse signal received from a broad-band antenna (1); a transmission path (2) having a predetermined length, transmitting the pulse signal received by the broad-band antenna (1) from the broad-band antenna (1) to the characteristic impedance unit (3), and transmitting the generated response signal from the characteristic impedance unit (3) to the broad-band antenna (1); and the broad-band antenna (1) for receiving the pulse signal and transmitting the response signal. The aforementioned pulse wave is transmitted to the radio tag TGn by the UWB method. The response signal from the radio tag TGn is received and the radio tag TGn is identified from the reception waveform.

Claims

1. A responder comprising:

a generating unit configured to generate a response signal, using a pulse signal that is received through a wideband antenna;

a transmitting unit configured to transmit the pulse signal received through the wideband antenna from the wideband antenna to the generating unit and also to transmit the response signal from the generating unit to the wideband antenna, the transmitting unit having a predetermined length; and

the wideband antenna that receives the pulse signal and transmits the response signal,

wherein the length of the transmitting unit is equal to or greater than a half a value obtained by multiplying a velocity at which the received pulse signal and the response signal are transmitted in the transmitting unit by a time equivalent to a pulse width of the received pulse signal.

2. The responder according to claim 1, wherein the transmitting unit located between the wideband antenna and the generating unit has such a length as to transmit the response signal through the wideband antenna in a different transmission manner from any transmission manner of other responders, the other responders each having the same structure as the responder.

3. The responder according to claim 1, wherein the transmitting unit has characteristic impedance that is constant at a predetermined value at a predetermined length.

4. The responder according to claim 1, wherein the generating unit includes a reflection control unit configured to control a pulse reflection coefficient for the received pulse signal.

5. The responder according to claim 1, wherein the generating unit includes a length control unit configured to control an effective length of the transmitting unit, based on a signal state in which the response signal is to be.

6. The responder according to claim 5, wherein the length control unit controls the length to be equivalent to a value obtained by multiplying the velocity at which the pulse signal and the response signal are transmitted in the transmitting unit by a period of time equivalent to the pulse width of the pulse signal, and then adding N/4 (N being 0 or a natural number) of the multiplication result to a half the multiplication result.

7. The responder according to claim 1, further comprising:

a plurality of generating units; and

a plurality of transmitting units configured to transmit the pulse signal received by the wideband antenna to each of the generating unit from the wideband antenna, and also to transmit the response signal from each of the plurality of generating units to the wideband antenna, the transmitting units having different lengths from one another.

8. The responder according to claim 7, further comprising:

a common transmitting unit configured to function as at least a part of each of the plurality of transmitting units.

9. The responder according to claim 1, wherein the generating unit includes a resonating unit that can resonate at a plurality of resonant frequencies.

10. An interrogator that transmits the pulse signal to the responder according to claim 9 and receives the response signal from the responder,

the interrogator comprising:

a generating unit configured to generate the pulse signal;

a wideband antenna configured to transmit the pulse signal to the responder, and to receive the response signal from the responder in response to the pulse signal;

an analyzing unit configured to perform frequency analysis by sampling the received response signal; and

an identifying unit configured to identify the responder, based on a result of the frequency analysis.

11. The interrogator according to claim 10, further comprising:

a superimposing unit configured to superimpose the received response signal with a template signal that is generated in advance, so as to generate a superimposed signal,

the analyzing unit performing frequency analysis by sampling the superimposed signal.

12. The interrogator according to claim 11, wherein the template signal is generated based on a clock signal that is generated in advance.

13. A responder comprising:

a plurality of element responders each being the responder according to claim 1, wherein at least one of the length of the transmitting unit and the load impedance of the transmitting unit and the generating unit seen from the wideband antenna is different in each one of the element responders from another.

14. The responder according to claim 1, further comprising:

a reception antenna configured to receive radio waves; and

a power supply unit configured to convert the received radio waves into electric power, and to supply the electric power to the generating unit.

15. The responder according to claim 14, wherein the radio waves are continuous waves.

16. The responder according to claim 14, wherein:

the reception antenna is a narrow-band antenna that is in tune with a predetermined tuning frequency; and

the radio waves are continuous waves having the tuning frequency.

17. The responder according to claim 14, wherein the wideband antenna also serves as the reception antenna.

18. An interrogator that transmits the pulse signal to the responder according to claim 1 and receives the response signal from the responder,

the interrogator comprising:

a pulse generating unit configured to generate the pulse signal;

a wideband antenna configured to transmit the pulse signal to the responder, and to receive the response signal from the responder in response to the pulse signal; and

an identifying unit configured to identify the responder by comparing the received response signal with a template signal that is generated in advance.

19. The interrogator according to claim 18, wherein:

the pulse generating unit comprises a first modulated clock signal generating unit configured to generate a first modulated clock signal by performing a first modulating operation on a clock signal, the pulse generating unit using the first modulated clock signal to generate and output the pulse signal to the wideband antenna; and

the identifying unit comprises a second modulated clock signal generating unit configured to generate a second modulated clock signal by performing a second modulating operation on the clock signal, the second modulating operation being different from the first modulating operation, the identifying unit using the second modulated clock signal to generate the template signal and to obtain correlations between the response signal and the template signal.

20. The interrogator according to claim 19, wherein the first modulating operation and the second modulating operation are to delay the cock signal based on a pseudo random code.

21. The interrogator according to claim 18, further comprising:

a reflected wave detecting unit configured to detect a reflected wave that is reflected by the wideband antenna of the responder in response to the received pulse signal;

a response wave detecting unit configured to detect a response wave contained in the response signal; and

a response wave interval detecting unit configured to detect a response wave interval that is a period elapsing between the time of receiving the reflected wave and the time of receiving the response wave,

the identifying unit identifying the responder, based on the detected response wave interval.

22. The interrogator according to claim 18, further comprising:

a transmission/reception interval detecting unit configured to detect a transmission/reception interval that is a period elapsing between the time of receiving a reflected wave reflected by the wideband antenna of the responder in response to the received pulse signal and the time of transmitting the pulse signal; and

a distance recognizing unit configured to recognize the distance between the interrogator and the responder that transmits the reflected wave, based on the detected transmission/reception interval.

23. The interrogator according to claim 18, further comprising:

a determining unit configured to determine the polarity of the response signal.

24. The interrogator according to claim 18, further comprising:

a radio wave transmitting unit configured to transmit the radio waves to a responder comprising a generating unit configured to generate a response signal, using a pulse signal that is received through a wideband antenna, a transmitting unit configured to transmit the pulse signal received through the wideband antenna from the wideband antenna to the generating unit and also to transmit the response signal from the generating unit to the wideband antenna, the transmitting unit having a predetermined length, and wherein the wideband antenna that receives the pulse signal and transmits the response signal, a reception antenna configured to receive radio waves, and a power supply unit configured to convert the received radio waves into electric power, and to supply the electric power to the generating unit.

25. A wireless communication system comprising:

one or a plurality of the responders according to claim 1;

a plurality of the interrogators, wherein each interrogator comprises a pulse generating unit configured to generate the pulse signal, a wideband antenna configured to transmit the pulse signal to the responder and to receive the response signal from the responder in response to the pulse signal, and an identifying unit configured to identify the responder by comparing the received response signal with a template signal that is generated in advance; and

a determining unit configured to determine the position of each of the responders, based on the distance between each of the responders and each of the interrogators, the distance being detected by each of the interrogators.

26. A position detecting system that includes a plurality of interrogators each transmitting a pulse signal as an interrogating wave, and a responder that receives the pulse signal and returns a response signal based on the received pulse signal,

the position detecting system comprising:

a first distance detecting unit configured to receive the pulse signal transmitted by each of the interrogators and to detect the distance between each two of the interrogators;

a second distance detecting unit configured to detect the distance between each of the interrogators and the responder, based on the pulse signal and the response signal; and

a device position detecting unit configured to detect the position of each of the interrogators and the responder in the position detecting system, based on each of the detected distances.

27. The position detecting system according to claim 26, further comprising:

a plurality of the responders;

a responder identifying unit configured to identify each of the responders, based on the response signal; and

a distance information transmitting unit configured to transmit distance information to each of the interrogators, the distance information indicating each of the detected distances.

28. The position detecting system according to claim 27, further including a fixed responder that can be fixed beforehand in a position in the position detecting system,

the position detecting system further comprising:

a third distance detecting unit configured to detect the distance between the fixed responder and each of the interrogators,

the device position detecting unit detecting the absolute position of each of the interrogators and each of the responders in the position detecting system, based on each of the detected distances.

29. The position detecting system according to claim 26, further comprising:

a receiving unit configured to receive a return signal that is returned from a moving body located in the position detecting system in response to the transmitted pulse signal;

a determining unit configured to determine whether the moving body is the responder, based on the received return signal; and

a reporting unit configured to report that the moving body is determined not to be the responder by the determining unit.

30. The position detecting system according to claim 27, wherein the distance information transmitting unit transmits the distance information in the form of pulse waves to each of the interrogators.

31. The position detecting system according to claim 26, further comprising:

an interrogator number detecting unit configured to detect the number of interrogators located in the position detecting system.

32. The responder that is in the position detecting system according to claim 26, comprising:

a wideband antenna configured to receive the transmitted pulse signal and transmits the response signal;

a generating unit configured to modulate the received pulse signal to generate the response signal; and

a transmitting unit configured to transmit the received pulse signal to the generating unit through the wideband antenna, and also to transmit the response signal from the generating unit to the wideband antenna.

33. A position detecting method that is utilized in a position detecting system that includes a plurality of interrogators each transmitting a pulse signal as an interrogating wave, and a responder that receives the pulse signal and returns a response signal based on the received pulse signal,

the position detecting method comprising:

a first distance detecting step of detecting the distance between each two of the interrogators after receiving the pulse signal transmitted by each of the interrogators;

a second distance detecting step of detecting the distance between each of the interrogators and the responder, based on the pulse signal and the response signal; and

a device position detecting step of detecting the position of each of the interrogators and the responder in the position detecting system, based on each of the detected distances.

34. The position detecting method according to claim 33, wherein the position detecting system includes a plurality of the responders,

the position detecting method further comprising the steps of:

identifying each of the responders, based on the response signal; and

transmitting distance information to each of the interrogators, the distance information indicating each of the detected distances.

35. A non-transitory computer-readable medium recording a program to be performed by a computer in a position detecting system that includes a plurality of interrogators each transmitting a pulse signal as an interrogating wave, and a responder that receives the pulse signal and returns a response signal based on the received pulse signal, the program comprising:

detecting the distance between each two of the interrogators after receiving the pulse signal transmitted by each of the interrogators;

detecting the distance between each of the interrogators and the responder, based on the pulse signal and the response signal; and

detecting the position of each of the interrogators and the responder in the position detecting system, based on each of the detected distances.