Abstract: Systems, software, devices, and methods are described for an RFID reader system to communicate with RFID tags. RF energy encountered in conjunction with using a selected channel is detected and used to adjust a waveform shaping parameter. RF waves can be transmitted from the reader to the RFID tags and RF waves can be backscattered from the RFID tags. At least some of the RF waves transmitted to or backscattered from the RFID tags have a waveform with a shape according to the adjusted waveform shaping parameter.

Abstract: Briefly, in accordance with one embodiment of the invention, an orthogonal frequency division multiplexing system may provide a dynamically calculated cyclic extension, the length of which may be based at least in part on a delay spread due to an experienced environmental condition. The length of the cyclic extension may be calculated by determining a channel impulse response, and then computing the energy distribution of the channel impulse response. The length of the cyclic extension may then be set according to the energy distribution of the channel impulse response.

Abstract: Systems, software, devices, and methods are described for an RFID reader system to communicate with RFID tags. RF energy encountered in conjunction with using a selected channel is detected and used to adjust a waveform shaping parameter in combination with a performance requirement. RF waves can be transmitted from the reader to the RFID tags and RF waves can be backscattered from the RFID tags. At least some of the RF waves transmitted to or backscattered from the RFID tags have a waveform with a shape according to the adjusted waveform shaping parameter.

Abstract: Fractional delay based digital rate conversion is employed for timing recovery from RFID tag responses at an RFID reader. Signal received from the tag is asynchronously sampled and interpolated. A desired time variant fractional delay coefficient is computed based on the interpolation and time offset is adjusted such that an output sample matches a target point. A data matched filter is optionally integrated with the fractional delay based digital rate converter, which includes a digital phase lock loop.

Abstract: RFID reader systems, chips, and methods deal with the occasional problem of environmental noise, such as interference from other RFID readers. An RF carrier at a center frequency is modulated, for causing an antenna to transmit a wireless signal to an RFID tag. One of a first and a second stored code modules is selected, such as by a selector. The code modules are each associated with a format, referenced to the center frequency, of a backscatter response of the RFID tag to the transmitted wireless signal, where the first code module is associated with a baseband modulation format, and the second code module is associated with a subcarrier modulation format. The transmitted wireless signal includes a command instructing the tag to backscatter according to the format of the selected code module. In addition, a wireless signal that is backscattered from the RFID tag in response to the command is demodulated according to the format of the selected code module.

Abstract: An RFID tag has an antenna to receive a configuration signal, and a circuit with a controller that can configure the RFID circuit responsive to the configuration signal. Configuring is such that the tag backscatters by impressing data either on the carrier frequency, or on a subcarrier in addition to the carrier signal, depending on the configuration signal. In the event of a subcarrier, the tag controller may optionally further determine a frequency of the subcarrier from the configuration signal. The tag may then be configured to backscatter differently, upon receiving a different configuration signal. A complementary reader transmits the configuration signal, thus imparting an operating parameter. The reader has an interface to receive an input indicative of a present geography, and a lookup table for determining an operating parameter based on the present geography. In one embodiment, the operating parameter is determined from regulations at that geographic location.

Abstract: An RFID integrated circuit includes a demodulator to receive a first signal, the first signal having been generated by an RFID reader responsive to detection of a first environmental condition. The RFID integrated circuit further includes a controller to set, based on the first signal, a modulation format for the RFID integrated circuit and to configure the RFID integrated circuit to modulate a backscatter signal according to the modulation format.

Abstract: Briefly, in accordance with one embodiment of the invention, an orthogonal frequency division multiplexing system may provide a dynamically calculated cyclic extension, the length of which may be based at least in part on a delay spread due to an experienced environmental condition. The length of the cyclic extension may be calculated by determining a channel impulse response, and then computing the energy distribution of the channel impulse response. The length of the cyclic extension may then be set according to the energy distribution of the channel impulse response.

Abstract: A communication system includes a timing circuit which generates phase conversion information from a transmitter to transfer data from a first clock domain to a second clock domain, and a receive phase calculation circuit which utilizes the phase information from the transmitter to transfer data from the second clock domain to the first clock domain. The timing circuit includes a transmit (TX) numerical controlled oscillator (NCO) and a modulo indicator, and the receive phase calculation circuit calculates a receive phase based on a modulo signal.