METHOD AND SYSTEM FOR RADIATED POWER CONTROL FOR SHORT RANGE RFID TAG READING

• US 20090021374A1
• Filed: 07/17/2007
• Published: 01/22/2009
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Psion PLC (Motorola Solutions, Inc.)
• Original Assignee: Psion Teklogix (Motorola Solutions, Inc.)
• Inventors: Stagg, Adrian Joseph
• Granted Patent: US 8,159,331 B2
• Time in Patent Office: Days
• US Class Current: 340/572.100
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• 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

Abstract

A method and system for power control for Radio Frequency Identification (RFID) tag reading is provided. The system includes a power amplifier for providing an RF transmit signal for the RFID tag reading. The RF transmit signal is provided to an antenna for radiating the transmit signal. The power of the radiated transmit signal defining a read range for the RFID tag reading. The system includes an attenuator provided between the power amplifier and the antenna for controlling the power of the radiated transmit signal to adjust the read range. A handheld RFID reader may include the system. The method includes calibrating the output power of a reader having a power amplifier and an attenuator provided between the power amplifier and an antenna. The step of calibrating includes at least one of controlling power of the power amplifier in its linear region, and controlling attenuation level of the attenuator.

Claims

1. A system for power control for Radio Frequency Identification (RFID) tag reading, comprising:

a power amplifier for providing an RF transmit signal for the RFID tag reading, the RF transmit signal being provided to an antenna for radiating the transmit signal, power of the radiated transmit signal defining a read range for the RFID tag reading; and

an attenuator provided between the power amplifier and the antenna for controlling the power of the radiated transmit signal to adjust the read range.

2. A system as claimed in claim 1, further comprising a module for controlling each of the power amplifier and the attenuator.

3. A system as claimed in claim 1, wherein the system comprises:

a module for calibrating at least one of power setting of the power amplifier, attenuation level of the attenuator or a combination thereof to read a single RFID tag.

4. A system as claimed in claim 3, further comprising a memory for storing one or more calibrated settings for the power amplifier and the attentuator, which is obtained by the calibration module, each of the calibrated settings being selectively enabled.

5. A system as claimed in claim 3, wherein the calibration module determines a maximum power setting and a minimum power setting to read the single RFID tag.

6. A system as claimed in claim 2, wherein the control module has functionality of operating the power amplifier in its linear region.

7. A system as claimed in claim 1, wherein the system comprises:

a radio module including;

an RF section having the power amplifier; and

a controller for communicating with a host and communicating with the RF section.

8. A system as claimed in claim 7, wherein the controller communicates with the host through a bi-directional link and decodes a command from the host.

9. A system as claimed in claim 8, wherein a voltage control of the power amplifier is written into a register based on the command from the host.

10. A system as claimed in claim 7, wherein the controller generates a control signal for controlling the attenuator.

11. A system as claimed in claim 7, wherein the attenuator is powered by the radio module or the host.

12. A system as claimed in claim 7, further comprising:

a radio interface for operably connecting the radio module and the host.

13. A system as claimed in claim 7, wherein the host is a handheld host terminal for the RFID tag reading.

14. A system as claimed in claim 7, wherein the RF Signal is connected between the radio module and the attenuator with an RF connection having a coax cable.

15. A system as claimed in claim 7, wherein the radio module provides at least one of power and a control signal to the attenuator via a flexible circuit.

16. A system as claimed in claim 7, wherein the system comprises:

a transmit path including the power amplifier and the attenuator; and

a receive path for receiving a response from one or more RFID tags.

17. A system as claimed in claim 1, wherein a host controls an output level of the power amplifier.

18. A system as claimed in claim 1, further comprising:

a host for controlling the power amplifier, the attenuator or a combination thereof for the RFID tag reading.

19. A handheld RFID reader comprising:

an antenna;

the power control system according to claim 1 and connected to the antenna;

a host communicating with the power control system for the RFID tag reading; and

a housing for the handheld RFID reader.

20. A handheld RFID reader as claimed in claim 19, wherein the host comprises:

a user interface for operating the reader for the RFID tag reading.

21. A handheld RFID reader as claimed in claim 19, wherein the host comprises:

a module for calibrating the output power of the radiated transmit signal to read a single RFID tag.

22. A method for power control for Radio Frequency identification (RFID) tag reading, comprising:

calibrating the output power of a reader, the reader including a power amplifier for providing an RF transmit signal for the RFID tag reading, an antenna for radiating the transmit signal and an attenuator provided between the power amplifier and the antenna, the output power of the reader defining a read range for the RFID tag reading, the step of calibrating including at least one of the following steps;

controlling power of the power amplifier in its linear region; and

controlling attenuation level of the attenuator.

23. A method as claimed in claim 22, wherein the step of calibrating comprises:

determining whether a single RFID tag is readable among a plurality of RFID tags; and

determining the setting for the power amplifier and the attenuator to read the single RFID tag.

24. A method as claimed in claim 23, further comprising:

operating the reader having the power amplifier, the attenuator and the antenna, comprising at least one of the steps of;

selectively retrieving the calibrated setting for the power amplifier and the attenuator to read the single RFID tag; and

adjusting the attenuation level of the attenuator.