RFID System and Method for Wirelessly Interfacing With an Interrogator

Abstract

A method of adjusting the 2-way communication range of an RFID system to assist a human operator to individually handle and interrogate a plurality of tagged objects, such as suitcases, that each include an RFID tag transceiver. An RFID interrogator transceiver is mounted on the human operator. The 2-way communication range between the interrogator transceiver and the tag transceivers is adjusted to only slightly exceed the closest distance between the interrogator and the tag while the operator is handling the tagged object. Preferably, the 2-way communication range is short enough that other tagged objects will remain outside the communication range and will not respond to messages from the interrogator. Another aspect of the invention is a method of verifying whether an object to be transported has reached its intended destination. In this aspect, an interrogator transceiver at a first destination interrogates an RFID tag transceiver on the object, and in response the tag transmits its intended destination.

1 - 27 . (canceled)  
     
     
         28 : A method of adjusting the two-way communication range of an RFID system to permit a person to individually handle and interrogate each one of a plurality of tagged objects, each tagged object having an RFID tag transceiver, the method comprising: 
 mounting on the person an RFID interrogator transceiver having an antenna configured to be worn by the person;    mounting on each tagged object an RFID tag transceiver, wherein 
 each tag transceiver is characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver, and  
 the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers; and  
   adjusting at least one of the interrogator performance parameters so that the reliable two-way communications range between the interrogator transceiver and the tag transceiver of each of the tagged objects only slightly exceeds the closest distance, during times when the person handles that tagged object, between the antenna of the interrogator and the tag transceiver mounted on that tagged object.    
     
     
         29 : A method in accordance with  claim 28  wherein adjusting at least one of the interrogator performance parameters comprises adjusting interrogator transmitter output power.  
     
     
         30 : A method in accordance with  claim 29  wherein interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         31 : A method in accordance with  claim 28 , wherein: 
 the performance parameters of each tag transceiver include a receiver sensitivity of the tag transceiver;    the performance parameters of the interrogator transceiver include a receiver sensitivity of the interrogator transceiver and a transmitter output power of the interrogator transceiver; and    the adjusting step includes adjusting at least one of the receiver sensitivity of the tag transceiver, the receiver sensitivity of the interrogator transceiver, and the transmitter output power of the interrogator transceiver.    
     
     
         32 : A method in accordance with  claim 28 , wherein each tag transceiver is a modulated backscatter transceiver.  
     
     
         33 : A method in accordance with  claim 28 , further comprising the steps of: 
 the interrogator transceiver transmitting an interrogation message while the person is close enough to a tagged object for the antenna of the interrogator transceiver and that transceiver of the tagged object to be within the communications range;    the transceiver of that tagged object transmitting, in response to the interrogation message, an identification message containing data identifying that tagged object; and    the interrogator transceiver receiving the identification message and presenting the data to said person.    
     
     
         34 : A method of adjusting the two-way communication range of an RFID system to permit a person to individually handle and interrogate each one of a plurality of tagged objects, each tagged object having an RFID tag transceiver, comprising: 
 supporting on the person a portable RFID interrogator transceiver;    mounting on each tagged object an RFID tag transceiver, wherein 
 each tag transceiver is characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver, and  
 the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers;  
   iteratively 
 transmitting an interrogation signal via the RFID interrogator;  
 determining at the RFID interrogator, based either on one or more response messages sent by the RFID tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and  
 adjusting at least one of the interrogator performance parameters or the transceiver performance parameters;  
   until the RFID tag transceiver of one of the tagged objects being individually handled by the person is within the reliable two-way communications range and the tag transceivers of the tagged objects not being individually handled are not within the reliable two-way communications range; and    wherein, in operation, the interrogator presents to the person an audio indication of data received from an interrogated tag.    
     
     
         35 : A method in accordance with  claim 34  wherein adjusting at least one of the interrogator performance parameters comprises adjusting interrogator transmitter output power.  
     
     
         36 : A method in accordance with  claim 35  wherein interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         37 : A method of adjusting the two-way communication range of an RFID system to permit a person to individually handle and interrogate each one of a plurality of tagged objects, each tagged object having an RFID tag transceiver, comprising the steps of: 
 mounting on the person an RFID interrogator transceiver having an antenna, with the antenna being configured to be worn by the person;    mounting on each tagged object an RFID tag transceiver, wherein 
 each tag transceiver is characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver, and  
 the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers, and  
   adjusting at least one of the interrogator performance parameters so that the reliable two-way communications range between the interrogator transceiver and the tag transceiver of each of the tagged objects exceeds the closest distance, during times when the person handles that tagged object, between the antenna of the interrogator and the tag transceiver mounted on that tagged object;    wherein the adjusting step further comprises adjusting said at least one of the performance parameters so that said reliable two-way communications range is short enough so that, when the person handles a tagged object, no other tagged object is within reliable two-way communication range of the interrogator.    
     
     
         38 : A method in accordance with  claim 37  wherein adjusting at least one of the interrogator performance parameters comprises adjusting interrogator transmitter output power.  
     
     
         39 : A method in accordance with  claim 38  wherein interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         40 : A method of adjusting the two-way communication range of an RFID system to permit a person to individually handle and interrogate each one of a plurality of tagged objects, each tagged object having an RFID tag transceiver, comprising the steps of: 
 mounting adjacent the person an RFID interrogator transceiver having an antenna;    mounting on each tagged object an RFID tag transceiver, wherein 
 each tag transceiver is characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver, and  
 the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers; and  
   adjusting at least one of the interrogator performance parameters so that the reliable two-way communications range between the interrogator transceiver and the tag transceiver of each of the tagged objects only slightly exceeds the closest distance, during times when the person handles that tagged object, between the antenna of the interrogator and that tagged object.    
     
     
         41 : A method in accordance with  claim 40 , wherein the step of mounting the interrogator transceiver further comprises: 
 mounting the interrogator transceiver on the person so as to leave the hands of the person free to grasp objects other than the interrogator transceiver.    
     
     
         42 : An RFID interrogator apparatus having an adjustable reliable two-way communication range so as to permit a person to individually interrogate the closest one of a plurality of nearby tagged objects, wherein each tagged object has a respective RFID tag transceiver attached thereto, comprising: 
 an RFID interrogator transceiver, configured to communicate with any of the RFID tag transmitters, including a transmitter and receiver and having adjustable transmitter power and adjustable receiver sensitivity;    an antenna coupled to the interrogator transceiver and which is adapted to be worn by a person, on the person's torso; and    a control logic circuit, connected to the interrogator transceiver, for iteratively transmitting an interrogation signal via the transmitter; 
 determining, based either on one or more response messages sent by the RFID tag transceivers to the RFID interrogator transceiver in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and  
 adjusting the transmitter power or receiver sensitivity;  
   until the RFID tag transceiver of the closest one of the tagged objects is within the reliable two-way communications range and the tag transceivers of the other tagged objects are not within the reliable two-way communications range.    
     
     
         43 : The apparatus of  claim 42  wherein the adjusting the transmitter power or receiver sensitivity comprises adjusting the transmitter power.  
     
     
         44 : The apparatus of  claim 43  wherein the control logic circuit is configured to select the transmitter power from among at least three different possible power levels.  
     
     
         45 : An RFID interrogator apparatus having an adjustable two-way communication range so as to permit a person to individually interrogate the closest one of a plurality of nearby tagged objects, wherein each tagged object has a respective RFID tag transceiver attached thereto, comprising: 
 an RFID interrogator transceiver characterized by a set of one or more performance parameters which control a reliable two-way communications range between the interrogator transceiver and any of the RFID tag transceivers;    an antenna coupled to the interrogator transceiver and which is adapted to be worn by a person; and    a control logic circuit, connected to the interrogator transceiver, for adjusting at least one of the interrogator performance parameters so that the reliable two-way communications range between the interrogator transceiver and the tag transceivers exceeds the closest distance, during times when said person handles a tagged object, between the antenna and the tag transceiver attached to that tagged object;    wherein the interrogator transceiver includes circuitry for detecting signal strength and circuitry for rejecting a signal whose strength is below a threshold signal strength.    
     
     
         46 : The apparatus of  claim 45  wherein the adjusting at least one of the interrogator performance parameters comprises adjusting interrogator transmitter output power.  
     
     
         47 : The apparatus of  claim 46  wherein the interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         48 : A method in accordance with  claim 50  wherein adjusting interrogator power comprises adjusting interrogator transmitter output power.  
     
     
         49 : A method in accordance with  claim 48  wherein interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         50 : A method comprising: 
 mounting on an airplane cargo door an RFID interrogator transceiver;    mounting on pieces of luggage respective RFID tag transceivers, wherein 
 each tag transceiver has adjustable sensitivity, and  
 the interrogator transceiver has adjustable power output; and iteratively 
 transmitting an interrogation signal via the RFID interrogator transceiver;  
 determining at the RFID interrogator transceiver, based either on one or more response messages sent by the RFID tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the pieces of luggage are within a reliable two-way communications range; and  
 adjusting the RFID interrogator transceiver power output or the sensitivity of the tag transceiver;  
 
 until the RFID tag transceiver of one of the pieces of luggage passing through the cargo door is within the reliable two-way communications range and the pieces of luggage not passing through the cargo door are not within the reliable two-way communications range.  
   
     
     
         51 : A method of adjusting the two-way communication range of an RFID system to permit a baggage handler to individually handle and interrogate each one of a plurality of tagged luggage items, each tagged luggage item having an RFID tag transceiver, the method comprising: 
 mounting on the baggage handler an RFID interrogator transceiver having an antenna configured to be worn by the person;    mounting on multiple tagged luggage items an RFID tag transceiver, wherein 
 respective tag transceivers are characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver;  
 tag transceivers respectively include memory configured to store data representing the intended destination of the luggage item to which the tag is mounted; and  
 the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers;  
 the interrogator transceiver includes a memory configured to store data representing the airport at which the interrogator is being used;  
   adjusting at least one of the interrogator performance parameters so that the reliable two-way communications range between the interrogator transceiver and the tag transceiver of each of the tagged objects only slightly exceeds the closest distance, during times when the person handles that tagged object, between the antenna of the interrogator and the tag transceiver mounted on that tagged object; and    comparing the data stored in the interrogator transceiver with data stored in a tag transceiver to determine if an item of luggage is at its destination.    
     
     
         52 : A method in accordance with  claim 51  wherein adjusting at least one of the interrogator performance parameters comprises adjusting interrogator transmitter output power.  
     
     
         53 : A method in accordance with  claim 52  wherein interrogator transmitter output power is selectable from among at least three different possible power levels.  
     
     
         54 : The method of  claim 28  wherein the antenna is configured to be worn by the person.  
     
     
         55 : The method of  claim 28  wherein adjusting at least one of the interrogator performance parameters comprises successively transmitting interrogation signals via the interrogator transceiver until the interrogator transceiver, in response to one of the interrogation signals, receives a response from the tagged object being handled by the person, the first interrogation signal being transmitted at a minimum power level and the subsequent interrogation signals being transmitted at successively higher power levels.  
     
     
         56 : The method of  claim 28  wherein adjusting at least one of the interrogator performance parameters comprises successively transmitting interrogation signals via the interrogator transceiver until the reliable two-way communications range only slightly exceeds the closest distance between the antenna of the interrogator and the tag transceiver mounted on the tagged object being handled by the person, the interrogator transceiver operating at a first level of receive sensitivity subsequent to the first interrogation signal being transmitted and operating at successively reduced levels of receive sensitivity subsequent to the transmission of each successive interrogation signal.  
     
     
         57 : The method of  claim 28  wherein the adjusting comprises iteratively 
 transmitting an interrogation signal via the RFID interrogator;    determining at the RFID interrogator, based either on one or more response messages sent by the RFID tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and    adjusting at least one of the interrogator performance parameters or the transceiver performance parameters;    until the RFID tag transceiver of one of the tagged objects being individually handled by the person is within the reliable two-way communications range and the tag transceivers of the tagged objects not being individually handled are not within the reliable two-way communications range.    
     
     
         58 : The method of  claim 37  wherein the interrogator transceiver includes memory storing data indicative of a location of the interrogator transceiver, the interrogator transceiver selectively receiving data indicative of an intended destination location of one of the tagged objects from the tag transceiver mounted on the one tagged object.  
     
     
         59 : The method of  claim 37  wherein the adjusting comprises iteratively 
 transmitting an interrogation signal via the RFID interrogator;    determining at the RFID interrogator, based either on one or more response messages sent by the RFID tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and    adjusting at least one of the interrogator performance parameters or the transceiver performance parameters;    until the RFID tag transceiver of one of the tagged objects being individually handled by the person is within the reliable two-way communications range and the tag transceivers of the tagged objects not being individually handled are not within the reliable two-way communications range.    
     
     
         60 : The method of  claim 40  wherein the adjusting comprises iteratively 
 transmitting an interrogation signal via the RFID interrogator;    determining at the RFID interrogator, based either on one or more response messages sent by the RFID tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and    adjusting at least one of the interrogator performance parameters or the transceiver performance parameters;    until the RFID tag transceiver of one of the tagged objects being individually handled by the person is within the reliable two-way communications range and the tag transceivers of the tagged objects not being individually handled are not within the reliable two-way communications range.    
     
     
         61 : The apparatus of  claim 42  wherein the RFID tag transceivers are modulated backscatter transceivers configured to reflect RF energy received by the respective RFID tag transceivers.  
     
     
         62 : The apparatus of  claim 45  wherein the control logic circuit is further configured for iteratively 
 transmitting an interrogation signal via the transceiver;    determining, based either on one or more response messages sent by the RFID tag transceivers to the RFID interrogator transceiver in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged objects are within the reliable two-way communications range; and    adjusting at least one of the performance parameters;    until the RFID tag transceiver of the closest one of the tagged objects is within the reliable two-way communications range and the tag transceivers of the tagged objects are not within the reliable two-way communications range.    
     
     
         63 : The method of  claim 51  further comprising: 
 receiving, at the interrogator, the data representing the intended destination of the luggage item to which the tag is mounted from at least one of the tag transceivers and comparing, at the interrogator, the data representing the airport at which the interrogator is being used with the data representing the intended destination of the luggage item; and    if the data representing the airport at which the interrogator is being used and the data representing the intended destination of the luggage item both refer to a same location, notifying the baggage handler.    
     
     
         64 : The method of  claim 51  wherein the adjusting comprises iteratively 
 transmitting an interrogation signal via the interrogator;    determining at the interrogator, based either on one or more response messages sent by the tag transceivers to the interrogator in response to the interrogation signal or on the absence of a response to the interrogation signal, which of the tagged luggage items are within the reliable two-way communications range; and    adjusting at least one of the interrogator performance parameters or the tag transceiver performance parameters;    until the RFID tag transceiver of one of the luggage items being individually handled by the baggage handler is within the reliable two-way communications range and the tag transceivers of the luggage not being individually handled are not within the reliable two-way communications range.    
     
     
         65 : The method of  claim 57  further comprising: 
 comparing, at the interrogator transceiver, the data indicative of the location of the interrogator transceiver with the data indicative of the intended destination location of the one tagged object; and    if the data indicative of the location of the interrogator transceiver and the data indicative of the intended destination location of the one tagged object both refer to a same location, notifying the person.    
     
     
         66 : The method of  claim 58  wherein at least one of the tag transceivers is a modulated backscatter transceiver configured to selectively reflect a continuous wave signal having a first frequency, the selectively reflected signal having a second frequency substantially the same as the first frequency.  
     
     
         67 : The method of  claim 63  wherein at least one of the tag transceivers is a modulated backscatter transceiver.  
     
     
         68 : The method of  claim 63  wherein the notifying the baggage handler comprises displaying an identifier associated with the baggage handler using a control center, the control center being configured to display identifiers of a plurality of other baggage handlers in addition to the notified baggage handler and to display an identifier associated with the intended destination of the luggage item as well as other identifiers associated with intended destinations of other luggage items handled by the plurality of other baggage handlers, the other identifiers being retrieved by the other baggage handlers using other interrogators.