Anti-jamming detector for radio frequency identification systems

• US 7,202,784 B1
• Filed: 06/16/2004
• Issued: 04/10/2007
• Est. Priority Date: 06/16/2004
• Status: Active Grant

• Current Assignee: NCR Voyix Corporation
• Original Assignee: NCR Corporation (NCR Voyix Corporation)
• Inventors: Herwig, Nathaniel Christopher
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): Previl; Daniel
• Application Number:
  US10/869,157
• Time in Patent Office: 1,028 Days
• Field of Search: 340/568.1, 340/572.1, 340/10.1, 340/10.5, 340/10.2, 340/5.92, 340/5.9, 340/572.3, 340/5.1, 340/825.36, 340/825.49, 340/10.3, 340/10.4, 340/10.42, 340/5.8, 340/572.8, 340/541
• US Class Current: 340/568.1
• 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: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2471 Antenna signal processing by receiver or emitter
• CPC Class Codes: H04K 2203/20 for contactless carriers, e.g. RFID carriers
• CPC Class Codes: H04K 3/22 including jamming detection and monitoring

Abstract

Systems and techniques for identifying the presence of a jamming signal impairing the operation of an RFID reader. An RFID reader includes a signal strength detector that detects and measures the signal strength of signals within a prescribed frequency range typical of that used by RFID devices. If a signal within the frequency range and exceeding a predetermined maximum strength is detected, the reader identifies the presence of a jamming signal impairing the proper operation of the reader. The reader takes appropriate action upon identification of a jamming signal, for example issuing a local alert or alarm, or sending a message to a central security station, which may then take appropriate action in response to the message, such as alerting appropriate personnel, sounding alarms or securing exits.

Claims

1. A radio frequency identification (RFID) reader, comprising:

a receiver for detecting and receiving signals emitted from one or more RFID devices;

a signal strength detector for determining strength of a detected signal within a prescribed frequency range typical of frequency ranges used by the RFID device and generating a signal strength detection signal indicating the signal strength; and

a processor for receiving the signal strength detection signal and determining whether the signal strength detection signal is indicative of detection of a signal strength above a prescribed maximum established to detect jamming signals, the processor being operative to identify a detected signal as a jamming signal if the signal strength detection signal indicates a signal strength above the prescribed maximum, the processor being further operative to select an appropriate response to the jamming signal from a plurality of available responses.

2. The reader of claim 1 further comprising:

a transmitter to broadcast a radio frequency (RF) signal that is modulated by one or more RFID devices within range.

3. The reader of claim 2, wherein the receiver detects modulated backscatter signals emitted by the one or more RFID devices and extracts identifying information from the RFID devices.

4. The reader of claim 3, wherein the reader is operative to issue an alert upon detection of a jamming signal, the alert indicating detection of a jamming signal and identifying the reader detecting the jamming signal.

5. The reader of claim 4, wherein the reader is operative to sound a local alarm upon detection of a jamming signal.

6. The reader of claim 1 wherein the transmitter broadcasts the radio frequency signal at a power of at least 1 W, and wherein said prescribed maximum is at least 500 mW.

7. A system for management and tracking of goods comprising:

a plurality of radio frequency identification (RFID) devices, each of the devices being operative to emit an RFID signal including product identification information for an associated product and device identification information specifically identifying the device;

a plurality of RFID readers operative to detect signals received from RFID devices, each of the readers being further operative to measure a signal strength of a signal within a predetermined frequency range typical of that within which the RFID devices operation and to identify a signal as a jamming signal interfering with proper operation of the reader if the signal exceeds a predetermined maximum signal strength, each reader being operative to select an appropriate response to identification of a signal as a jamming signal, the response being one of a plurality of available responses.

8. The system of claim 7, wherein each of the readers is operative to issue an alert upon identification of a jamming signal, each alert identifying the reader issuing the alert.

9. The system of claim 8, further comprising:

a central security station for receiving an alert from a reader and taking appropriate action in response to the alert.

10. The system of claim 9, wherein the action taken by the central security station include one or more of issuing an audible or visual alarm, alerting a responsible employee and securing an entrance or exit.

11. The system of claim 10, wherein each of the readers is operative to provide detailed information about a detected jamming signal to the central security station and wherein the central security station is operative to store the information for examination in order to provide insight into potential interference problems affecting the operation of the system.

12. The system of claim 9 wherein the central security station records details of interfering signals, said details including frequency and power, and said details taken from samples taken over time.

13. A method of management and tracking of goods identified by radio frequency identification (RFID) devices, comprising:

communicating with a plurality of RFID devices in order to receive information from the devices;

measuring the strength of each received signal within a prescribed frequency range typical of the range used by the RFID devices;

if a received signal within the prescribed frequency range exceeds a predetermined maximum established to detect jamming signals, identifying the presence of a jamming signal; and

selecting an appropriate response to the identification of the jamming signal, the response being selected from a plurality of available responses.

14. The method of claim 13, wherein the step of identifying the presence of a jamming signal is followed by a step of taking appropriate action in response to detection of the jamming signal.

15. The method of claim 14, wherein the step of taking appropriate action includes one or more of issuing a local alarm and issuing an alert to a central security station to allow action by the central security station.

16. The method of claim 15, wherein the action by the central security station includes one or more of issuing an audible or visual alarm, alerting an appropriate employee and securing an entrance or exit.

17. The method of claim 16, further comprising:

storing detailed information relating to each jamming signal detected in order to allow for later examination in order to provide insight into possible interference problems affecting reception of RFID signals.

18. The method of claim 13 further comprising:

recording details of interfering signals including frequency and power, said details taken from samples over time.