Identification of objects by a reader
First Claim
1. A method of identifying objects by an interrogator, comprising the steps of:
- transmitting an interrogation signal from the interrogator to the object;
transmitting from each object to the interrogator an identification signal having predetermined indicator characteristics in response to the interrogation signal;
receiving the identification signal from the object at the interrogator and substantially contemporaneously determining at the interrogator whether any identification signal has been individually and correctly received or not on the basic of the indicator characteristics;
substantially contemporaneously transmitting from the interrogator a common re-transmit or interrupt signal to the objects in the event of the interrogator detecting a corrupted transmission state arising from any identification signal not being individually and correctly received; and
independently ceasing signal transmission from an object if that object successfully completes its signal transmission without receiving an interrupt signal from the interrogator during such transmission.
1 Assignment
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Accused Products
Abstract
An identification system is provided for identifying a plurality of object-based transponders (14, 16, 18, 20) using an interrogator (10). The interrogator (10) includes a transmitter for transmitting an interrogation signal to the transponders, a receiver for receiving identification signals from the transponders, and processor means (21) for determining the individual and correct receipt of an identification signal. The transponders operate on the basis of backscatter modulation, and include a detector for detecting the presence of an interrupt signal from the interrogator. Control logic responsive to the detector is arranged to cease signal transmission from the transponder if the transponder completes transmission of the identification signal without receiving an interrupt signal during such transmission. The interrogator (10) is arranged to receive the identification signals from the transponders (14, 16, 18, 20) and substantially contemporaneously to determine if any identification signal has been individually and correctly received. In the event of any identification signal is being individually and correctly received, the interrogator (10), at substantially the same time, transmits a common interrupt signal for temporarily suspending signal transmission from a transponder (14) if the transponder is transmitting its identification signal at the time it receives the interrupt signal. The transponder (14) independently ceases signal transmission if it completes transmission of an identification signal without receiving an interrupt signal.
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Citations
26 Claims
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1. A method of identifying objects by an interrogator, comprising the steps of:
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transmitting an interrogation signal from the interrogator to the object;
transmitting from each object to the interrogator an identification signal having predetermined indicator characteristics in response to the interrogation signal;
receiving the identification signal from the object at the interrogator and substantially contemporaneously determining at the interrogator whether any identification signal has been individually and correctly received or not on the basic of the indicator characteristics;
substantially contemporaneously transmitting from the interrogator a common re-transmit or interrupt signal to the objects in the event of the interrogator detecting a corrupted transmission state arising from any identification signal not being individually and correctly received; and
independently ceasing signal transmission from an object if that object successfully completes its signal transmission without receiving an interrupt signal from the interrogator during such transmission. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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- 12. An identification system comprising an interrogator and a plurality of object-based responders, the interrogator including transmitter means for transmitting an interrogation signal to the responders, receiver means for receiving identification signals from the responders in response to the interrogation signal, processor means for determining whether an identification signal is individually and correctly received or not and for generating an interrupt signal in the event of a failed transmission being received from any one or more of the responders, each responder comprising a receiver for receiving the interrogation signal, identification signal generator means for generating the identification signal, a transmitter for repeatedly transmitting the identification signal back to the interrogator, a detector for detecting the presence of an interrupt signal from the interrogator, and control means responsive to the detector and being arranged independently to tease signal transmission from the responder if the responder completes transmission of the identification signal without receiving an interrupt signal during such transmission.
- 16. A responder for an identification system of the type comprising an interrogator and a plurality of responders, each responder comprising a receiver for receiving an interrogation signal, first memory means for storing identification data, an oscillator, a modulator for deriving a modulated identification signal from the identification data and the oscillator, and a transmitter for repeatedly transmitting the identification signal back to the interrogator, the responder further comprising a detector for detecting the presence of an interrupt signal from the interrogator, signal ceasing means arranged independently to cease signal transmission from the responder if the responder completes transmission of the identification signal without receiving an interrupt signal from the interrogator during such transmission, and signal suspending means responsive to the detector and being arranged temporarily to suspend transmission of an identification signal from the responder if the responder is transmitting its identification signal at the time it receives the interrupt signal.
- 22. An interrogator for an identification system of the type comprising an interrogator and a plurality of object based responders, the interrogator including transmitter means for transmitting an interrogation signal to the responders, receiver means for receiving identification signals from the responders in response to the interrogation signal, first processor means for substantially contemporaneously determining the individual and correct receipt of an identification signal, signal generator means responsive to the first processor means for generating substantially contemporaneously an interrupt signal in the event of any identification signal not being individually and correctly received from any one or more responders, and for causing the interrupt signal to be transmitted sufficiently quickly to suspend signal transmission from any such responder whilst it was not individually and correctly transmitting its identification signal.
Specification