SYSTEMS AND METHODS FOR POWER SUPPLY SYNCHRONIZATION IN RADIO FREQUENCY IDENTIFICATION (RFID) READERS

• US 20090261659A1
• Filed: 04/17/2009
• Published: 10/22/2009
• Est. Priority Date: 04/17/2008
• Status: Active Grant

• Current Assignee: Novanta Corporation (Novanta Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Honore, Francis, Carrick, John C., Herold, Robert R.
• Granted Patent: US 8,196,831 B2
• Time in Patent Office: Days
• US Class Current: 307/82
• 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: G06K 7/10207 parameter settings related to power consumption of the interrogator

Abstract

A system for power supply synchronization in an Radio Frequency Identification (RFID) reader is shown and described. In one embodiment, the system includes one or more switched mode power supply devices and a signal generator. Each of the switched mode power supply devices provides power to at least one component of the RFID reader. The signal generator transmits a synchronization signal of a controlling frequency to each of the one or more power supply devices. In one embodiment, the system includes a signal processing unit that is configured to reject one or more spectral components from the output of the RFID reader.

Claims

1. A system for power supply synchronization in a Radio Frequency Identification (RFID) reader, the system comprising:

one or more switched mode power supply devices, each of the one or more devices providing power to at least one component of an RFID reader; and

a signal generator, in communication with each of the one or more switched mode power supply devices, transmitting a synchronization signal comprising a controlling frequency to each of the one or more switched mode power supply devices.

2. The system of claim 1 further comprising a signal processing unit in communication with the RFID reader, rejecting one or more spectral components from an output of the RFID reader.

3. The system of claim 1, wherein the controlling frequency is chosen to be substantially equal to an integer multiple of a channel spacing between adjacent RFID channels.

4. The system of claim 1, wherein the signal generator comprises an oscillator, in communication with a digital divider circuit, generating the synchronization signal comprising the controlling frequency.

5. The system of claim 4 further comprising a modulator, in connection with the oscillator and digital divider circuit, spreading the spectrum of the generated signal.

6. The system of claim 4, wherein the oscillator has a duty cycle substantially in agreement with a duty cycle requirement of the one or more switched mode power supply devices.

7. A method for power supply synchronization in a Radio Frequency Identification (RFID) reader, the method comprising:

generating, by a signal generator, a synchronization signal comprising a controlling frequency;

receiving, by one or more switched mode power supply devices in communication with one or more components of a Radio Frequency Identification (RFID) reader, the synchronization signal; and

synchronizing the one or more switched mode power supply devices to the controlling frequency.

8. The method of claim 7, wherein the synchronizing occurs responsive to the one or more switched mode power supply devices receiving the synchronizing signal.

9. The method of claim 7, wherein the controlling frequency is substantially equal to an integer multiple of a channel spacing between adjacent RFID channels.

10. The method of claim 7 further comprising generating, by an oscillator, a first signal of a first frequency and dividing, by a digital divider circuit, the frequency of the first signal to generate the synchronization signal.

11. The method of claim 10, wherein the oscillator has a duty cycle substantially in agreement with a duty cycle requirement of the one or more switched mode power supply devices.

12. The method of claim 10 further comprising spreading, in communication with a modulator, the spectrum of the first signal.

13. A system for power supply synchronization in a Radio Frequency Identification (RFID) reader, the system comprising:

means for generating a synchronization signal of a controlling frequency; and

means for synchronizing the one or more switched mode power supply devices to the controlling frequency.

14. A method of signal processing on a Radio Frequency Identification (RFID) reader, the method comprising:

generating, by a signal generator, a controlling frequency;

synchronizing one or more switched mode power supply devices to the controlling frequency, each of the one or more switched mode power supply devices providing power to at least one component of the RFID reader;

controlling, by the signal generator, spectral location of switching noise of the one or more switched mode power supply devices such that the switching noise of each of the one or more switched mode power supply devices appear at a substantially same spectral location and harmonics thereof; and

rejecting, by a filtering device, spectral components due to the switching noise of the one or more switched mode power supply devices.

15. The method of claim 14 further comprising generating, by an oscillator, a first signal of a first frequency and dividing, by a digital divider circuit, the frequency of the first signal to generate a synchronization signal comprising the controlling frequency.

16. The method of claim 15, wherein the oscillator has a duty cycle substantially in agreement with a duty cycle requirement of the one or more switched mode power supply device.

17. The method of claim 15 further comprising spreading, in communication with a modulator, the spectrum of the first signal.

18. The method of claim 14, wherein the controlling frequency is substantially equal to an integer multiple of a channel spacing between adjacent RFID channels.

19. The method of claim 14, wherein the rejecting step further comprises removing a spectral component due to a direct current (DC) bias.

20. The method of claim 14, wherein the rejecting step further comprises removing spectral components due to responses from adjacent RFID readers.

21. The method of claim 14, wherein the filtering device comprises a digital filter.

22. The method of claim 14, wherein the filtering device comprises an analog filter.