Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

In some aspects, material processing head can include a body; an antenna disposed within the body; a first tag, associated with a first consumable component, disposed within a flux communication zone of the body at a first distance from the antenna, the first tag having a first resonant frequency; and a second tag, associated with a second consumable component, disposed within the flux communication zone of the body at a second distance from the antenna, the second tag having a second resonant frequency that is different than the first resonant frequency, where the first and second resonant frequencies are tuned based upon at least one of: i) a difference between the first distance and the second distance; or ii) a characteristic (e.g., shape) of the flux communication zone in which the first tag and/or the second tag is disposed.

A Radio Frequency Identification (RFID) tag IC stores an identifier and a check code. The IC determines whether the stored identifier is corrupted by comparing it to the check code. If the stored identifier does not correspond to the check code then the IC may terminate operation or indicate an error. The IC may also reconstruct the correct identifier from the check code.

Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

Methods and systems are provided for controlling an RFID emission within an environment including a sensitive object whose operation may be affected by RFID emissions above a particular strength. An RFID reader of the system is configured to emit a reader signal, while a host is associated with the RFID reader and configured to define the strength of the reader signal. A guard tag is configured to receive the reader signal and, upon receiving the reader signal, emit a return signal to be received by the RFID reader. The host is further configured to, upon the RFID reader receiving the return signal, decrease the strength of the reader signal and/or change the direction in which the reader signal is emitted, preferably until no further reader signal is received by the RFID reader.

RFID tags may compensate for non-RFID power sources by automatically enforcing data or state persistence even while powered. A tag may measure a time interval between successive detected reader commands. If the interval exceeds a minimum time, then the tag may deassert a protocol flag, erase data, and/or change tag operating states, even if the tag would normally not perform these actions while powered.

Various embodiments relate to a method for classifying received radio frequency signals, including: receiving an input signal; matched filtering the input signal to produce a correlation result signal; sampling the correlation result signal at a plurality of half-bit-grids and a plurality of bit-grids to produce a set of modulated phase correlation result samples and a set of non-modulated phase correlation result samples; calculating a minimum of the set of modulated phase correlation result samples; calculating a maximum of the set of non-modulated phase correlation result samples; and classifying the input signal as valid data or collision data based on the minimum and the maximum.

In some aspects, material processing head can include a body; an antenna disposed within the body; a first tag, associated with a first consumable component, disposed within a flux communication zone of the body at a first distance from the antenna, the first tag having a first resonant frequency; and a second tag, associated with a second consumable component, disposed within the flux communication zone of the body at a second distance from the antenna, the second tag having a second resonant frequency that is different than the first resonant frequency, where the first and second resonant frequencies are tuned based upon at least one of: i) a difference between the first distance and the second distance; or ii) a characteristic (e.g., shape) of the flux communication zone in which the first tag and/or the second tag is disposed.

A method and apparatus for detecting a bulk quantity of RFID tags in a presentation area such as a point-of-sale device. Bulk quantity of RFID tags may be detected according to input to the point-of-sale device including through input from a symbolic barcode scanner, a conveyor belt, a weight scale, and/or via an RF antenna driven at a first power level. After the bulk quantity of RFID tags is detected, the RF antenna is driven at a second, higher power level temporarily to increase bulk RFID tag detection accuracy. Fringe tags may be detected by the RF antenna when it is driven at the higher power level that are in the environment but not presented at the point-of-sale device. Fringe tags may be filtered based on RF characterization of the presentation area including driving the RF antenna outside of presentation sessions and/or filtering RFID tags detected across multiple presentation sessions.

A method for interleaving time slots in a multi-antenna system for communication with RFID tags is described. An exemplary system has a first RFID interrogator and first and second antennas. The first and second antennas direct signals to and receive signals from respective first and second interrogation zones. A first interrogation signal is transmitted to the first antenna. A first acquire window for receiving a signal from a first RFID transponder is opened after the first interrogation signal. A second interrogation signal is transmitted to the second antenna after the first interrogation signal, and a second acquire window for receiving a signal from a second RFID transponder is opened after the second interrogation signal.