Transmitter and a method for transmitting data

• US 20060022797A1
• Filed: 08/26/2004
• Published: 02/02/2006
• Est. Priority Date: 12/24/1997
• Status: Active Grant

• Current Assignee: SATO Holdings Corporation
• Original Assignee: Magellan Technology Pty. Ltd (SATO Holdings Corporation)
• Inventors: Littlechild, Stuart Colin, Murdoch, Graham Alexander Munro
• Granted Patent: US 7,978,073 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H03C 3/00 Angle modulation H03C5/00, H03C7/00 take precedence

Abstract

Apparatus and methods for transmitting data include using data to phase modulate a carrier signal to have side bands substantially lower in amplitude than the carrier. Phase modulation may be less than 90 degrees. The apparatus and methods may apply transponders, RFID apparatus and methods, passive signal devices, and single antenna equipment and methods.

Claims

1. A method of transmitting data and a powering signal from a first antenna, said method comprising the steps of:

providing a carrier signal;

imposing a phase modulation of less than 90°

on the carrier signal in accordance with a data signal to create a modulated signal having a carrier frequency and sidebands, the sidebands being substantially lower in amplitude than the carrier frequency; and

providing the modulated signal to said first antenna for transmission.

2. A method according to claim 1, comprising the step of receiving the modulated signal with a second antenna which, in response thereto, produces a first signal which is provided to receiver means, the receiver means deriving a second signal indicative of the data signal.

3. A method according to claim 2, wherein the first signal is used to power the receiver means.

4. A method according to claim 2, wherein both the first and second antennas have a high Q factor.

5. A method according to claim 1, comprising the step of deriving the modulated signal from the sum of the carrier signal and an attenuated quadrature carrier signal which is modulated with the data signal.

6. A device comprising:

a first antenna;

oscillator means for providing a carrier signal; and

mixing means for imposing a phase modulation of less than 90°

on the carrier signal in accordance with a data signal to create a modulated signal, the mixing means also providing the modulated signal to the first antenna for transmission, wherein the modulated signal has a carrier frequency and sidebands, the sidebands being substantially lower in amplitude than the carrier frequency.

7. A device according to claim 6, wherein the modulated signal is received by a second antenna which, in response thereto, produces a first signal which is provided to receiver means, the receiver means deriving a second signal indicative of the data signal.

8. A device according to claim 7, wherein the first signal is used to power the receiver means.

9. A device according to claim 6, wherein at least one of the first and second antennas have a high Q factor.

10. A device as claimed in claim 6, wherein at least one of the first and second antennas have a low Q factor.

12. A device according to claim 6, wherein the antenna is a tunable coil.

13. A device as claimed in claim 6, wherein the receiver means is a Radio Frequency Identification Device.

14. A device as claimed in claim 6, wherein the receiver means is a passive device.

15. A device as claimed in claim 6, wherein the receiver means is a transponder.

16. A luggage identification system comprising a device as defined in claim 6.

18. A method as claimed in claim 14, wherein the modulation is phase quadrature modulation.

19. A method as claimed in claim 14, wherein the phase modulation is attenuated.

20. A method according to claim 14, further comprising the step of deriving the modulated signal from the sum of the carrier signal and an attenuated quadrature carrier signal which is modulated with the data signal.

21. A method as claimed in claim 20, further comprising the step of phase shifting the carrier signal 90 degrees to produce the quadrature signal.

22. A method as claimed in claim 21 further comprising the step of modulating the quadrature signal with data.

23. A method as claimed in claim 22, wherein the modulation is phase reverse keying PRK.

11. A device according to clam 6, wherein the modulated signal includes the sum of the carrier signal and an attenuated quadrature carrier signal which is modulated with the data signal.

17. A method for transmitting data from a device having a first antenna, said method comprising the steps of:

providing a carrier signal;

imposing a phase modulation on the carrier signal in accordance with a data signal to create a modulated signal having a carrier and sidebands, the amount of phase modulation being selected such that the amplitude of the sidebands is substantially lower than that of the carrier; and

transmitting the modulated signal from the first antenna.

24. A method of imposing a low level signal having a modulated quadrature component on a carrier signal, the method comprising the steps of:

providing a carrier signal, and

imposing on the low level signal, a data signal to create a modulated signal.

25. A method as claimed in claim 24, wherein the modulated signal has a carrier and sidebands, the amount of phase modulation being selected such that the amplitude of the sidebands is substantially lower than that of the carrier.

26. A method as claimed in claim 24, wherein the modulation is phase quadrature modulation.

27. A method as claimed in claim 24, wherein the phase modulation is attenuated.

28. A method according to claim 24, further comprising the step of deriving a modulated signal for transmission from the sum of the carrier signal and an attenuated quadrature carrier signal which is modulated with the data signal.

29. A method as claimed in claim 28, further comprising the step of phase shifting the carrier signal 90 degrees to produce the quadrature signal.

30. A method as claimed in claim 29, further comprising the step of modulating the quadrature signal with data.

31. A method as claimed in claim 30, wherein the modulation is phase reverse keying PRK.

32. A method of transmitting data from a first antenna, said method comprising the steps of:

providing a modulated signal as claimed in claim 24, and

providing the modulated signal to said first antenna for transmission.

33. A method as claimed in claim 32, wherein the modulated signal is phase modulation.

34. A method as claimed in claim 32, wherein the modulated signal is amplitude modulation.

35. A method as claimed in claim 32, wherein the low level signal is phase jitter.

36. A method as claimed in claim 32, wherein the modulation is phase jitter modulation.

37. A method as claimed in claim 32, further comprising the step of passing the signal through a phase shifter.

38. A method as claimed in claim 32, further comprising the step of passing the signal through an RC filter.

39. A method as claimed in claim 32, further comprising the step of passing the signal through a tuned circuit.

40. A method as claimed in claim 32, further comprising the step of passing the signal through a variable length delay means.

41. A method as claimed in claim 32, wherein the step of imposing a low level phase modulation includes the step of imposing a phase modulation of less than 90°

on the carrier signal in accordance with a data signal to create a modulated signal having a carrier frequency and sidebands.

42. A method as claimed in claim 32, wherein the signal provided to the first antenna is amplitude limited.

43. A method as claimed in claim 32, wherein the phase deviation caused by the low level signal is arctan (2×

Mag(PRK)/Mag(Fc)), where

PRK is the modulated quadrature component, and

Fc is the excitation signal.

44. A method as claimed in claim 43, wherein for a 40 dB attenuated PRK signal, the phase deviation is 1.2 degrees.

45. A method as claimed in claim 43, wherein for a 60 dB attenuated PRK signal, the phase deviation is 0.12 degrees.

46. A device comprising:

a first antenna;

oscillator means for providing a carrier signal; and

mixing means for imposing a low level phase modulation on the carrier signal in accordance with the method as claimed in claim 24, the mixing means also providing the modulated signal to the first antenna for transmission.

47. The transmitter of claim 46, wherein the low level phase modulation is less than 90°

and wherein the modulated signal has a carrier frequency and sidebands.

48. A device as claimed in claim 46, operatively adapted to transmit data from the first antenna in accordance with the method of claim 35.

49. A device adapted to receiving a modulated signal and derive there from a data signal, the device comprising:

an antenna adapted to receive the modulated signal and, in response thereto, produce a first signal,

receiver means adapted to derive from the first signal, a local oscillator signal used to demodulate the first signal and obtain an indicative data signal.

50. A device as claimed in claim 49, wherein the receiver includes a phase locked loop to derive the local oscillator signal.

51. A device as claimed in claim 50, wherein the phase locked loop is a low loop bandwidth phase locked loop.

52. A device as claimed in claim 49, wherein the receiver includes a mixer in demodulating the first signal.

53. A device as claimed in claim 49, wherein the receiver includes a multiplier in demodulating the first signal.

54. A device as claimed in claim 49, wherein the first signal is used as a source of power for the device means.

55. A device according to claim 49, wherein the antenna has a high Q factor.

56. A device as claimed in claim 49, wherein the device is a Radio Frequency Identification Device.

57. A device as claimed in claim 49, wherein the device is a passive device.

58. A device as claimed in claim 49, wherein the device is a transponder.

59. A method of demodulating a modulated signal received by a device and deriving there from a data signal, the method comprising the steps of

receiving the modulated signal

producing a first signal being a local oscillator signal,

demodulating the modulated signal using the local oscillator signal to obtain an indicative data signal.

60. A method as claimed in claim 59, wherein a phase locked loop is used to derive the local oscillator signal.

61. A method as claimed in claim 60, wherein the phase locked loop is a low loop bandwidth phase locked loop.

62. A method as claimed in claim 59, wherein a mixer is used in demodulating the first signal.

63. A method as claimed in claim 59, wherein a multiplier is used in demodulating the first signal.

64. A method as claimed in claim 59, wherein a low pass filter is used to filter out high frequency signal components and pass the demodulated data signal.

65. A method as claimed in claim 59, wherein the first signal is used as a source of power for the device means.

66. A method of encoding a data signal for transmission by a device, the method comprising the steps of:

providing an excitation reference signal,

passing the reference signal through a 90 degree splitter,

combining one output from the splitter with a data signal, and

adding another output from the splitter to the combined data signal for transmission.

67. A method as claimed in claim 66, wherein the data signal is PRK modulated.

68. A method as claimed in claim 66, wherein the combined data signal is PRK quadrature modulated.

69. A method as claimed in claim 66, wherein the combined data signal is attenuated.

70. A method of demodulating a modulated signal received by a device and deriving there from a data signal, the method comprising the steps of:

receiving the modulated signal and inducing into an antenna of the device, an antenna voltage signal,

amplifying the antenna signal

providing a portion of the amplified signal to a phase locked loop to filter off sidebands and creating a first signal

passing another portion of the amplified signal through a delay means and creating a second signal

XORing the first and second signals to provide indicative data.

71. A method as claimed in claim 70, wherein the antenna signal is amplified by squaring the signal by a Schmitt trigger device.

72. A method as claimed in claim 70, wherein the phase locked loop is a low bandwidth phase locked loop device.

73. A method as claimed in claim 70, wherein the data is detected using a floating point comparator device.