EP0467036A2
Expired / Lapsed
EP
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Method and apparatus for radio identification and tracking
Assignee: Savi Technology Inc
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Filing: 1991-05-15
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Granted: —
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Expires: 2011-05-15
Abstract
Abstract Items are identified and tracked by attaching radio transceiver tags to the items and sending signals between the tags and one or more interrogation subsystems. The tags are normally in low-power standby mode unless signalled by an interrogator. The interrogator broadcasts a signal to all of the tags within reception range, and the tags respond after pseudo-random delays. When the interrogator has identified a tag, it signals that fact back to the tag and the tag returns to standby mode. The tags that were not identified by the interrogator retransmit their identification signals, and the process continues until all tags within range of the interrogator have been identified. <IMAGE>
Inventors
- 👤 Robert S. Reis
- 👤 Richard K. Stevens
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 11:59
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10009; G06K7/10316; G06K7/10346; G01; G01S; G01S13/00; G01S13/74; G01S13/76; G01S13/767; G06K7/0008; G06K7/10019; G06K7/10029; G06K7/10059; G01S13/75; G01S13/751; G01S13/765
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
86 words
A method for identifying and tracking items, characterized in that a transceiver tag is associated to each of the items to be tracked; an interrogation signal is transmitted to the transceiver tags; identification signals are selectively transmitted from the transceiver tags responsive to reception of the interrogation signal by the transceiver tags; the identification signals are received; a verification signal is transmitted responsive to receipt of the identification signals; and additional identification signals are transmitted from the transceiver tags responsive to receipt of the verification signal.
Claim 2
Independent Claim
86 words
A method for identifying and tracking items, characterized in that a transceiver tag is associated to each of the items to be tracked; an interrogation signal is transmitted to the transceiver tags; identification signals are selectively transmitted from the transceiver tags responsive to reception of the interrogation signal by the transceiver tags; the identification signals are received; a verification signal is transmitted responsive to receipt of the identification signals; and additional identification signals are transmitted from the transceiver tags responsive to receipt of the verification signal.
Claim 3
Dependent Claim
20 words
The method according to claim 1, characterized in that the interrogation signal is transmitted by a central interrogation transceiver subsystem.
Claim 4
Independent Claim
23 words
The method according to claims 1 or 2, characterized in that all tags within receiving range of the interrogation signal transmit identification signals.
Claim 5
Independent Claim
45 words
The method according to claims 1, 2 or 3, characterized in that the step of selectively transmitting identification signals further comprises the step of each tag delaying initiation of transmission of the identification signal a particular amount of time after receipt of the interrogation signal.
Claim 6
Independent Claim
24 words
The method as in claims 1, 2, 3 or 4, characterized in that the particular amount of time is determined in a psuedo-random manner.
Claim 7
Dependent Claim
58 words
Apparatus for identifying and tracking items, characterized in that a plurality of transceiver tags (8, 120, 130, 140) are affixed to the items; an interrogation transceiver subsystem (7) communicates with the transceiver tags, the interrogation transceiver subsystem having the capability to initiate the transmission of an identification signal from selected tags and identify the tags sending identification signals.
Claim 8
Dependent Claim
58 words
Apparatus for identifying and tracking items, characterized in that a plurality of transceiver tags (8, 120, 130, 140) are affixed to the items; an interrogation transceiver subsystem (7) communicates with the transceiver tags, the interrogation transceiver subsystem having the capability to initiate the transmission of an identification signal from selected tags and identify the tags sending identification signals.
Claim 9
Dependent Claim
34 words
Apparatus as in claim 6, characterized in that the transceiver tags (8, 120, 130, 140) remain in a low-power standby mode until activated by a wake-up signal (81) from the interrogation transceiver subsystem (7).
Claim 10
Dependent Claim
36 words
Apparatus as in claims 6 or 7, characterized in that the initiation of identification signals is responsive to receipt by transceiver tags (8, 120, 130, 140) of an initiation signal from the interrogation transceiver subsystem (7).
Claim 11
Dependent Claim
23 words
Apparatus as in claims 6, 7 or 8, characterized in that the identification signal from each tag (8, 120, 130, 140) is unique.
Claim 12
Dependent Claim
32 words
Apparatus as in claims 6, 7, 8 or 9, characterized in that a power strobe circuit periodically provides a signal to a microprocessor in each transceiver tag to cause low-power standby operation.
Claim 13
Dependent Claim
48 words
Apparatus as in claims 7, 8, 9 or 10, characterized in that protocol signal control means prevent communication loss between the interrogation transceiver subsystem (7) and the transceiver tags (8, 120, 130, 140) due to simultaneous identification transmissions from two or more transceiver tags (8, 120, 130, 140).
Claim 14
Dependent Claim
40 words
Apparatus as in claims 6, 7, 8, 9, 10 or 11, characterized in that protocol means iteratively acknowledges receipt of identification information from particular tags and requests remaining tags to resend identification transmissions until all responding tags have been identified.
Claim 15
Dependent Claim
46 words
Apparatus as in claim 12, characterized in that the protocol means further comprises means in the transceiver tags (8, 120, 130, 140) for delaying identification transmissions by each remaining tag for a particular period of time after the protocol means signal that retransmission will be required.
Claim 16
Dependent Claim
26 words
Apparatus as in claim 13, characterized in that the particular period of time is different for each remaining tag and is determined in a pseudo-random manner.
Claim 17
Dependent Claim
33 words
Apparatus as in claims 6, 7, 8, 9, 10, 11, 12, 13 or 14 further characterized in that the apparatus comprises means for determining the location of transceiver tags (8, 120, 130, 140).
References Cited (Backward Citations)
No citation records indexed.
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