Systems and Methods to Determine Motion Parameters Using RFID Tags

A system, comprising:

• a plurality of devices disposed in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the memory and commands modulated on the radio frequency signals;
• and
• a reader configured to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal, the reader is further configured to transmit the subsequent radio frequency signal in response to which the first device having the first identifier is configured to provide at least one second radio frequency signal;
• wherein the reader comprises a data processing system configured to determine a motion of the first device, based on a Doppler frequency shift detected in the at least one second radio frequency signal.

A reader, comprising:

• a signal generator having an oscillator and configured to generate radio frequency signals to a plurality of devices positioned in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to the radio frequency signals broadcast to the field based on commands modulated on the radio frequency signals;
• at least one transceiver coupled with the signal generator to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal;
• a first antenna positioned at a first location to receive a first signal from the first device having the first identifier responsive to the subsequent radio frequency signal;
• a second antenna positioned at a second location to receive a second signal from the first device having the first identifier responsive to the subsequent radio frequency signal;
• and
• a processor coupled with the at least one transceiver to determine a motion of the first device, based on a Doppler frequency shift detected from the first signal received via the first antenna and the second signal received via the second antenna.