Method, system, and apparatus for remote data calibration of a RFID tag population

A method for defining data symbols in a radio frequency identification (RFID) tag device, comprising:

• (a) receiving a first calibration signal;
• (b) detecting a characteristic of the received first calibration signal;
• and
• (c) storing the detected characteristic of the received first calibration signal as a stored first characteristic;
• wherein a received data symbol is determined to be a first data value if a characteristic of the received data symbol has a first predetermined relationship with the stored first characteristic;
• and
• wherein the received data symbol is determined to be a second data value if the characteristic of the received data symbol has a second predetermined relationship with the stored first characteristic.

A system for defining data symbols in a radio frequency identification (RFID) tag device, comprising:

• means for receiving a first calibration signal;
• means for detecting a characteristic of the received first calibration signal;
• and
• means for storing the detected characteristic of the received first calibration signal as a stored first characteristic;
• means for determining a received data symbol to be a first data value if a characteristic of the received data symbol has a first predetermined relationship with the stored first characteristic, or to be a second data value if the characteristic of the received data symbol has a second predetermined relationship with the stored first characteristic.

A method for communicating with radio frequency identification (RFID) tag devices, comprising:

• (a) transmitting a calibration signal having a characteristic;
• and
• (b) transmitting a data symbol;
• wherein a RFID tag device that receives the calibration symbol and the data symbol uses the characteristic to determine a data value of the data symbol.

A method for communicating with radio frequency identification (RFID) tag devices, comprising:

• (a) transmitting a first calibration signal having a first characteristic;
• (b) transmitting a second calibration signal having a second characteristic;
• and
• (c) transmitting a data symbol;
• wherein a RFID tag device that receives the first calibration symbol, the second calibration symbol, and the data symbol uses the first and second characteristics to determine a data value of the data symbol.

A radio frequency identification (RFID) reader, comprising:

• a transmitter;
• and
• an antenna coupled to an output of said transmitter;
• wherein said transmitter is capable of outputting a calibration signal for transmit by said antenna, wherein said calibration signal has a characteristic,
• wherein said transmitter is capable of outputting a data symbol for transmit by said antenna;
• wherein a RFID tag device that receives said calibration symbol and said data symbol uses said characteristic to determine a data value of said data symbol.

A radio frequency identification (RFID) reader, comprising:

• a transmitter;
• and
• an antenna coupled to an output of said transmitter;
• wherein said transmitter is capable of outputting first and second calibration signals for transmit by said antenna, wherein said first calibration signal has a first characteristic and said second calibration signal has a second characteristic;
• wherein said transmitter is capable of outputting a data symbol for transmit by said antenna;
• wherein a RFID tag device that receives said first calibration symbol, said second calibration symbol, and said data symbol uses said first and second characteristics to determine a data value of said data symbol.

A radio frequency identification (RFID) communications system, comprising:

• a RFID reader that includes a transmitter and an antenna coupled to an output of said transmitter;
• and
• a RFID tag device;
• wherein said transmitter is capable of outputting a calibration signal for transmit by said antenna, wherein said calibration signal has a characteristic,
• wherein said transmitter is capable of outputting a data symbol for transmit by said antenna;
• wherein said RFID tag device is configured to receive said calibration symbol and said data symbol, and is configured to use said characteristic to determine a data value of said data symbol.

A radio frequency identification (RFID) communications system, comprising:

• a RFID reader that includes a transmitter and an antenna coupled to an output of said transmitter;
• and
• a RFID tag device;
• wherein said transmitter is capable of outputting first and second calibration signals for transmit by said antenna, wherein said first calibration signal has a first characteristic and said second calibration signal has a second characteristic,
• wherein said transmitter is capable of outputting a data symbol for transmit by said antenna;
• wherein said RFID tag device is configured to receive said first calibration symbol, said second calibration symbol, and said data symbol, and is configured to use said first and second characteristics to determine a data value of said data symbol.