Method for locating a detection microchip

• US 7,391,360 B2
• Filed: 02/28/2006
• Issued: 06/24/2008
• Est. Priority Date: 02/28/2005
• Status: Expired due to Fees

• Current Assignee: Astra Gesellschaft Fur Asset Management mbH & Company KG
• Original Assignee: Astra Gesellschaft Fur Asset Management mbH & Company KG
• Inventors: Werner, Andreas, Merk, Holger, Stobbe, Anatoli
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US11/364,656
• Publication Number:
  US 20060220861A1
• Time in Patent Office: 847 Days
• Field of Search: 342/107, 342/109, 342/112, 342/105, 342/146, 342/194, 342/125, 342/126, 342/165, 342/173, 342/174, 340/572.1
• US Class Current: 342/107
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/84 for distance determination by phase measurement
• 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: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

A method is described for locating a detection microchip that transmits a detection signal, which is received and evaluated by a reader. The current distance between the reader and the detection microchip is determined from a run-time dependent feature of the received detection signal and the propagation speed of electromagnetic waves.

Claims

1. A method for locating a detection microchip that transmits a detection signal, which is received and evaluated by a reader, comprising determining the current distance between the reader and the detection microchip from a run-time-dependent characteristic of the received detection signal and propagation speed of electromagnetic waves, wherein:

the phase angle of the detection signal is evaluated as the run-time-dependent characteristic of the received detection signal,

a reference detection microchip is disposed at a reference distance from the reader in the vicinity of the detection microchips to be identified, wherein correction value for the reference distance is determined by comparing the measured phase angle to a reference phase angle, and the measured phase angle of the detection microchip to be identified is corrected with the correction value; and

multiple distance measurements are carried out at no less than two different antenna positions of the reader or a plurality of readers and the position of the detection microchip is determined from the intersection points of the distance position curves of the antenna positions of the reader or readers.

2. The method according to claim 1, wherein at least during a locating period, the detection microchip receives a carrier signal from the reader and transmits a detection signal that is modulated with a modulation signal and has the same frequency as the carrier signal, the modulation signal having signal points that are approximable by a straight line in a signal space diagram, wherein the detection signal received by the reader is demodulated, the difference between the phase angle of the detection signal and a reference phase angle is determined for a current distance between the detection microchip and the reader, and the current distance between the detection microchip and the reader is determined and from the difference of the phase angle, the carrier frequency and the propagation speed of the electromagnetic waves.

3. The method according to claim 1, wherein at least during a locating period, the detection microchip receives signals on a first and then at least a second frequency from the reader carrier and transmits detection signals, each modulated by a modulation signal and each having the same frequency as the carrier signals, the modulation signals having signal points that are approximable by a straight line in a signal space diagram, wherein the detection signals received by the reader are demodulated, the respective phase angle of each detection signal is determined and the current distance between the detection microchip and the reader is determined via shared analysis from the phase angles, the carrier frequencies and the propagation speed of the electromagnetic waves.

4. The method according to claim 1, wherein at least during a locating period, the detection microchip receives carrier signals on a first and simultaneously on at least one second frequency from the reader and transmits detection signals, being modulated by a modulation signal and each having the same frequency as the carrier signals, the modulation signals having signal points that are approximable by a straight line in a signal space diagram, wherein the detection signals received by the reader are split and demodulated by filters, the respective phase angle of the detection signal in question is determined, and the current distance between the detection microchip and the reader is determined from the phase angles, the carrier frequencies and the propagation speed of the electromagnetic waves via shared simultaneous analysis.

5. The method according to claim 1, wherein the phase angle is determined at least twice during the locating period with a time interval and a change of the phase angle in the time interval is determined as a relative movement between reader and detection microchip, while a correspondence is determined as a constant distance between reader and detection microchip.

6. The method according to claim 5, wherein the speed or directional vector of the movement is determined from the magnitude of the change of the distance or phase angle within a time interval.

7. The method according to claim 2 wherein the detection signal received by the reader is split into an in-phase and a quadrature component, one amplitude value each is determined from the in-phase and the quadrature components, and the phase angle is determined by a trigonometric function.

8. The method according to claim 7, wherein a resulting amplitude value is determined from the amplitude values of the in-phase and the quadrature components and the resulting amplitude value is evaluated for verification of the distance or at a known distance for testing the quality of a detection microchip.

9. The method according to claim 2, wherein during the locating period the detection signal is modulated with a signal that switches between at least two states, wherein the detection signal received by the reader is split into an in-phase component and a quadrature component in a demodulator and the in-phase component of the modulation signal is derived from the difference between the signal portions of the at least two states for the in-phase component and the quadrature component of the modulation signal is derived from the difference between the signal portions of the at least two states for the quadrature component, and wherein the phase angle is then determined trigonometrically from the in-phase component of the modulation signal and the quadrature component of the modulation signal.

10. The method according to claim 9, wherein the signal portions of the at least two states are evaluated over at least one evaluation period with at least two evaluation functions containing an expected signal sequence, and wherein an evaluation result returning a maximum amplitude is evaluated as the amplitude of the signal portions of the at least two states.

11. The method according to claim 9, wherein amplitudes of the signal portions of the at least two states are determined over multiple evaluation periods.

12. The method according to claim 1, wherein the reference detection signal of the reference detection microchip is modulated with a modulation signal differing from the modulation signal of the detection microchip to be identified, and the reference detection signal of the reference detection microchip and the detection signal of the detection microchip to be identified are separated by filters and simultaneously analyzed in the reader.

13. The method according to claim 1, wherein the different antenna positions are controlled by switching among multiple positionally separated antennae of the reader or readers.

14. The method according to claim 1, wherein after determination of the position of the detection microchip, the radiation lobe of an antenna array including at least two positionally separated antennae is aligned by phaseshifted control of the antennae in the direction of the detection microchip.

15. The method according to claim 1 wherein the detection microchip is activated from at least two different antenna positions before the distance measurement by the reader.

16. The method according to claim 3, wherein the detection microchip is activated on at least two different carrier frequencies before the distance measurement by the reader.