Apparatus and method for remotely testing a passive integrated transponder tag interrogation system

• US 6,184,777 B1
• Filed: 08/26/1997
• Issued: 02/06/2001
• Est. Priority Date: 08/26/1997
• Status: Expired due to Term

• Current Assignee: Destron Fearing Corporation (Merck & Co., Inc.)
• Original Assignee: Destron Fearing Corporation (Merck & Co., Inc.)
• Inventors: Mejia, Ezequiel
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): Asongwed, Anthony A
• Application Number:
  US08/918,482
• Time in Patent Office: 1,260 Days
• Field of Search: 340/825.54, 340/825.34, 340/572, 340/571, 340/825.69, 340/825.72, 341/176
• US Class Current: 340/10.1
• 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: G06K 7/0095 Testing the sensing arrangement, e.g. testing if a magnetic card reader, bar code reader, RFID interrogator or smart card reader functions properly testing of electrical circuits G01R31/28
• CPC Class Codes: G06K 7/10465 the interrogation device being capable of self-diagnosis, e.g. in addition to or as part of the actual interrogation process testing of electrical circuits in general G01R31/28
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal

Abstract

A remotely testable Passive Integrated Transponder (PIT) tag interrogation system is described. The system comprises a remotely activated test PIT tag fixed within the field of the system antenna. By selectively activating the test PIT tag, and determining successful receipt of the test tag identification signal during such activation, remote confirmation of proper operation of the system is achieved. The system also contains components which permit the remote detection of the antenna field by analyzing signals present in the antenna during operation. Remote detection of the natural frequency to which the antenna is tuned is also achieved by analyzing signals present in the antenna during the collapse of the electromagnetic field in the antenna when the antenna drive signal is removed.

Claims

1. A method of testing a passive integrated transponder (PIT) tag interrogation system having at least one antenna element and at least one remote test PIT tag fixedly positioned proximate said antenna element comprising the steps of:

causing said antenna element to emit a field of excitation energy at an energy level sufficient to energize a PIT tag coming within said field;

selectively enabling said remote test PIT tag to receive said excitation energy and to emit a remote test PIT tag identification signal in response thereto for receipt by said antenna element; and

detecting the remote test PIT tag identification signal received by said antenna element, thereby confirming the operation of said PIT tag interrogation system; and

further comprising the steps of driving said antenna element at a predetermined frequency and energy level via an antenna drive signal; and

detecting the voltage present in said driven antenna element to confirm proper operation thereof;

and further comprising the steps of determining the resonant frequency of said antenna element by;

removing said antenna drive signal from said antenna element; and

detecting the frequency of the voltage present in said antenna element as said antenna element voltage decays in the absence of said drive signal.

2. A method of testing a passive integrated transponder (PIT) tag interrogation system having at least one antenna element and at least one remote test PIT tag fixedly positioned proximate said antenna element comprising the steps of:

causing said antenna element to emit a field of excitation energy at an energy level sufficient to energize a PIT tag coming within said field;

selectively enabling said remote test PIT tag to receive said excitation energy and to emit a remote test PIT tag identification signal in response thereto for receipt by said antenna element; and

detecting the remote test PIT tag identification signal received by said antenna element, thereby confirming the operation of said PIT tag interrogation system; and

further comprising the steps of driving said antenna element at a predetermined frequently via an antenna drive signal;

detecting a waveform representative of the voltage present in said driven antenna element;

converting said detected waveform into a digital signal representative of said voltage;

ad

analyzing said digital signal to confirm the proper operation of said antenna element.

3. The method of claim 2, further comprising the steps of determining the resonant frequency of said antenna element by:

removing said antenna drive signal from said antenna element;

detecting a waveform representative of the voltage present in said antenna element as said antenna element voltage decays in the absence of said drive signal;

converting said detected voltage decay waveform into a digital test signal representative of said voltage decay waveform; and

analyzing said digital test signal so as to determine the frequency of said voltage decay waveform.