Method and system for conserving power in a recognition system
First Claim
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1. A transponder operable to communicate in a wireless fashion with an interrogator, said transponder comprising:
- a) a receiver for receiving RF energy;
b) a transponder controller in electrical communication with said receiver, said transponder controller being normally in a quiescent, power conserving condition and, in response to a wake-up signal, assuming a higher power-consuming condition wherein said controller is operable to receive an RF interrogation from said interrogator and to perform operations in response thereto;
c) a first stage circuit for receiving said RF energy from said receiver and for sending said wake-up signal if said received RF energy has certain predetermined characteristics;
d) a wake-up controller operable to intercept said wake-up signal from reaching said transponder controller for a power saving period if no proper RF interrogation is received during the reception of said RF energy, in spite of said RF energy having the certain predetermined characteristics necessary for said first stage circuit to send said wake-up signal, said wake-up controller upon expiration of said power saving period further serving to again pass said wake-up signal from said first stage circuit to said transponder controller.
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Abstract
A system and method for avoiding the discharge of a battery or otherwise excessive power consumption by a transponder (14) in the presence of a spurious noise source. In a described embodiment, the transponder (14) renders itself immune to activation by presence of RF energy for some period if the transponder does not receive a proper wake-up message within an activation period.
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Citations
23 Claims
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1. A transponder operable to communicate in a wireless fashion with an interrogator, said transponder comprising:
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a) a receiver for receiving RF energy; b) a transponder controller in electrical communication with said receiver, said transponder controller being normally in a quiescent, power conserving condition and, in response to a wake-up signal, assuming a higher power-consuming condition wherein said controller is operable to receive an RF interrogation from said interrogator and to perform operations in response thereto; c) a first stage circuit for receiving said RF energy from said receiver and for sending said wake-up signal if said received RF energy has certain predetermined characteristics; d) a wake-up controller operable to intercept said wake-up signal from reaching said transponder controller for a power saving period if no proper RF interrogation is received during the reception of said RF energy, in spite of said RF energy having the certain predetermined characteristics necessary for said first stage circuit to send said wake-up signal, said wake-up controller upon expiration of said power saving period further serving to again pass said wake-up signal from said first stage circuit to said transponder controller. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A transponder operable to communicate in a wireless fashion with an interrogator, said transponder comprising:
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a) a receiver for receiving RF energy; b) a transponder controller in electrical communication with said receiver, said transponder controller being normally in a quiescent, power conserving condition and, in response to a wake-up signal, assuming a higher power-consuming condition wherein said controller is operable to receive an RF interrogation from said interrogator and to perform operations in response thereto; c) a first stage circuit for receiving said RF energy from said receiver and for sending said wake-up signal if said received RF energy has certain predetermined characteristics; d) a wake-up controller comprising a wake-up counter and an interference counter, said wake-up controller being operable to intercept said wake-up signal from reaching said transponder controller for a power saving period if no proper RF interrogation is received during the reception of said RF energy, despite said RF energy having the certain predetermined characteristics necessary for said first stage circuit to send said wake-up signal, said wake-up controller further serving to again pass said wake-up signal from said first stage circuit to said transponder controller upon expiration of said power saving period, the duration of which is a function of the count loaded in said wake-up counter, the count in turn being a function of the value of the count stored in the interference counter, which increments each time said transponder controller receives a wake-up signal without receiving an proper RF interrogation, whereby the duration of the power saving period is generally proportional to the number of consecutive times that the transponder controller receives a wake-up signal without receiving a proper RF interrogation.
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9. A method for conserving power in a recognition system, the method comprising the steps of:
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a) receiving in a transponder an RF signal; b) testing said RF signal in said transponder for a certain predetermined threshold characteristic; c) upon detection of said certain predetermined threshold characteristic, activating in said transponder an activation timer that is operable to set an activation period during which said transponder tests said RF signal for a proper RF interrogation signal; and d) entering a power saving mode if no proper RF interrogation signal is received during said activation period wherein said transponder is impervious to subsequent RF signals for a power saving period. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for conserving power in a recognition system, the method comprising the steps of:
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a) receiving in a transponder an RF signal; b) activating in said transponder an activation counter; c) testing in said transponder said RF signal for a proper interrogation signal from an interrogator; d) incrementing an interference counter upon said activation counter decrementing to zero without said transponder having received said proper RF interrogation signal; e) activating in said transponder a wake-up counter, said wake-up counter being loaded with a value proportional to the count stored in said interference counter; and f) placing said transponder into a power saving mode whereby said transponder is impervious to subsequent RF signals for a power saving period wherein said power saving period continues while said wake-up counter decrements to zero. - View Dependent Claims (20, 21, 22)
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23. An improved transponder of the type (a) which is capable of receiving and processing valid signals, (b) which is capable of receiving, but not processing spurious signals, (c) which, prior to the receipt of either signal, is normally in a sleep state wherein it consumes a relatively low level of power from a source, and (d) which, upon receipt of either signal, assumes a wakened state wherein it consumes a relatively high level of power from the source, wherein the improvement comprises:
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first means (a) responsive to receipt of a first spurious signal while the transponder is in the normal sleep state for preventing the transponder from leaving the sleep state for a first time period which is a function of the duration of the first spurious signal, and (b) responsive to receipt of a subsequent spurious signal which occurs or is extant at the expiration of the first time period for preventing the transponder from leaving the sleep state for a second time period which is the sum of (i) the first time period and (ii) a time period which is a function of the duration of the second spurious signal beginning with the expiration of the first time period, the transponder being incapable of receiving or processing signals during the first or second time periods; and second means responsive to the absence of a spurious signal while the transponder is not being prevented from leaving the sleep state by the first means (a) for permitting the transponder to assume the wakened state, and (b) for causing the first means to respond to a spurious signal which occurs after such absence as a first spurious signal.
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Specification