Adaptively transmitting a signal for activating a tag

• US 20060220792A1
• Filed: 03/07/2006
• Published: 10/05/2006
• Est. Priority Date: 03/07/2005
• Status: Active Grant

• Current Assignee: Sensormatic Electronics LLC (Johnson Controls International plc)
• Original Assignee: Sensormatic Electronics Corporation (Johnson Controls International plc)
• Inventors: Frederick, Thomas J., Oakes, Jeffrey T.
• Granted Patent: US 7,564,355 B2
• Time in Patent Office: Days
• US Class Current: 340/10.300
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00
• CPC Class Codes: H04B 1/40 Circuits

Abstract

Adaptive transmission of a tag activation signal and detection of a tag. By monitoring the effects of a load on a tag activation signal, a signal analyzer adjusts the transmission waveform from which the signal is generated so that the next tag activation signal transmitted into the load more closely corresponds to a desired activation signal.

Claims

1. An apparatus for transmitting a signal for activating a tag comprising:

a transmitter controller for providing a transmission waveform;

a transmitter circuit for receiving the provided transmission waveform and providing a transmission signal corresponding to said transmission waveform, said transmission signal being adapted to activate a tag;

a signal analysis device for receiving the transmission signal, determining at least one variance characteristic of said transmission signal, and adjusting the transmitter controller in response to the determined variance characteristic of the transmission signal determined for improving the determined variance characteristic.

2. The apparatus of claim 1 wherein the signal analysis device further comprises:

an analog to digital converter for receiving the transmission signal and providing a digitized transmission signal representative of the received transmission signal;

a waveform analysis device for receiving the digitized transmission signal and determining the at least one variance characteristic of said digitized transmission signal; and

a logic device for receiving the determined characteristic of the digitized transmission signal and adjusting the transmitter controller in response to determined characteristic received thereby.

3. The apparatus of claim 1 wherein adjusting the transmission controller comprises adjusting waveform parameters that the transmission controller uses to determine the transmission waveform.

4. The apparatus of claim 1 wherein the at least one variance characteristic of the transmission signal comprises one or more of the following:

risetime, overshoot, regulation, lagging, ringing, and oscillation.

5. The apparatus of claim 4 wherein if a variance characteristic of ringing is determined, the signal analysis device is configured to not determine any other variance characteristics.

6. The apparatus of claim 4 wherein if a variance characteristic of oscillation is determined, the signal analysis device is configured to not determine any other variance characteristics.

7. The apparatus of claim 1 wherein the at least one variance characteristic is improved for subsequent tag activation signals.

8. The apparatus of claim 1 wherein the transmission signal is broadcast within a range, said range being at least partially determined by a current level supplied to the transmitter circuit.

9. The apparatus of claim 8 wherein the current level is adjusted as a function of a schedule, said schedule being based on at least one of the time of day, the day of the week, the day of the month, and the day of the year.

10. The apparatus of claim 1 wherein the transmission signal is periodic, repeating, and of a set frequency, duration, and duty cycle.

11. A method of controlling a transmission signal for activating a tag comprising:

determining at least one variance characteristic of a transmission signal, said transmission signal being adapted to activate a tag;

adjusting a transmission waveform from which the transmission signal is generated based on the determined variance characteristic such that the variance characteristic is improved; and

transmitting an adjusted transmission signal corresponding to the adjusted transmission waveform.

12. The method of claim 11 wherein adjusting a transmission waveform comprises:

receiving the determined variance characteristic of the transmission signal; and

adjusting parameters used to determine the transmission waveform in response to the determined characteristic.

13. The method of claim 11 wherein variance characteristics comprise one or more of the following:

risetime, overshoot, regulation, lagging, ringing, and oscillation.

14. The method of claim 13 wherein said determining at least one variance characteristic of the transmission signal further comprises:

determining if the transmission signal is oscillating and if the transmission signal is oscillating, only determining an oscillation variance characteristic of the transmission signal;

determining if the transmission signal is ringing and if the transmission signal is ringing, only determining a ringing variance characteristic of the transmission signal;

determining if the transmission signal is overshooting;

determining if the transmission signal is lagging; and

determining if the transmission signal is inadequately regulated.

15. The method of claim 11 wherein adjusting the transmission controller comprises adjusting proportional, integral, and derivative parameters that are used to determine the transmission waveform.

16. The method of claim 11 wherein the at least one variance characteristic is improved for subsequent tag activation signals.

17. The method of claim 11 wherein the adjusted transmission signal is broadcast within a range, said range being determined by a current level used in said transmitting.

18. The method of claim 17 wherein the current level is adjusted as a function of a schedule, said schedule being based on at least one of the time of day, the day of the week, the day of the month, and the day of the year.

19. The method of claim 11 wherein the transmission signal is periodic, repeating, and of a set frequency, duration, and duty cycle.

20. A system for providing an alarm signal comprising:

a transmitter controller for providing a transmission waveform;

a transmitter circuit for receiving the transmission waveform and providing a transmission signal corresponding to said transmission waveform;

an antenna for broadcasting the transmission signal within a range and for receiving a detection signal from within the range;

a plurality of tags for receiving the broadcast transmission signal and providing a corresponding detection signal to the antenna, wherein said detection signal is positive if any of the plurality of tags is within the range and negative if none of the plurality of tags are within the range;

a signal analysis device for receiving the transmission signal and the detection signal and for determining at least one variance characteristic of said transmission signal, and adjusting the transmitter controller in response to the determined variance characteristic to improve said variance characteristic.

21. The system of claim 20 wherein the signal analysis device further comprises:

an analog to digital converter for receiving the transmission signal and the detection signal and providing a digitized signal representative of the received signals;

a waveform analysis device for receiving the digitized transmission signal and determining at least one variance characteristic of said digitized transmission signal; and

a logic device for receiving the at least one variance characteristic of the digitized transmission signal and adjusting at least one parameter in a set of parameters used by the transmitter controller to determine the transmission waveform in response to the determined variance characteristic received thereby.

22. The system of claim 20 wherein said signal analysis device is configured to provide an alarm signal when the detection signal received by the antenna is determined to be positive.

23. The system of claim 20 wherein variance characteristics comprise one or more of the following:

risetime, overshoot, regulation, lagging, ringing, and oscillation.

24. The system of claim 20 wherein adjusting the transmission controller comprises adjusting proportional, integral, and derivative parameters that are used to determine the transmission waveform.

25. The system of claim 20 wherein the at least one variance characteristic is improved for subsequent RFID tag activation signals.

26. The system of claim 20 wherein said range is determined by a current level supplied to the transmitter circuit.

27. The system of claim 26 wherein the current level is adjusted as a function of a schedule, said schedule being based on at least one of the time of day, the day of the week, the day of the month, and the day of the year.

28. The system of claim 20 wherein the transmission signal is periodic, repeating, and of a set frequency, duration, and duty cycle.