Abstract: Radio-frequency identification (RFID) systems use readers to query and locate passive RFID tags in stores, warehouses, and other environments. A signal from the reader powers up the tag, which modulates and backscatters the signal toward the reader. The reader or an appliance coupled to the reader can estimate the tag's position based on the angle of arrival (AOA) of the backscattered signal. In some situations, AOA measurements by different readers may yield different position estimates for the same tag. If these position estimates are close enough to each other (e.g., within the expected imprecision or error radius), they can be averaged to improve precision. If not, the appliance can measure the variance or another measure of dispersion for each reader's position estimates, then pick the reader with the lowest dispersion as the preferred or best sensor for locating that tag, improving precision and reducing processing time.

Abstract: When a radio-frequency identification (RFID) tag reader queries an RFID tag, the reader or an appliance coupled to the reader derives a channel estimate from the tag's reply to the reader's query. The channel estimate represents the communications channel between the reader and that tag—or more precisely between the reader and the tag's location. This channel estimate acts as a fingerprint or signature for the communications channel between the reader and the tag's location. If the tag's environment is relatively static, then the channel estimate should be relatively stable, even if the tag is moved. The reader or appliance creates a library of tag locations indexed by channel estimate for each tag within range of the reader. When the reader receives a reply from a tag at an unknown location, the reader or appliance computes the corresponding channel estimate and uses that channel estimate to look up the closest location in the library of tag locations.

Abstract: A receiver for a multi-channel system such as a HDMI system is presented. In accordance with the present invention, the receiver receives one of the plurality of channels and includes an analog portion, a digital-to-analog converter, and a digital control block that provides digital control signals to the analog portion. Equalization can be accomplished partially or wholly in the analog domain and digitally controlled by a digital control loop. A digital equalizer can also be included. A decision feedback equalizer can be implemented that sums an analog output signal into the analog data stream. Timing recovery can be accomplished by digital control of a phase interpolator or delay locked loop that receives a plurality of phases from a timing circuit coupled to receive a clock signal.

Abstract: A receiver for a multi-channel system such as a HDMI system is presented. In accordance with the present invention, the receiver receives one of the plurality of channels and includes an analog portion, a digital-to-analog converter, and a digital control block that provides digital control signals to the analog portion. Equalization can be accomplished partially or wholly in the analog domain and digitally controlled by a digital control loop. A digital equalizer can also be included. A decision feedback equalizer can be implemented that sums an analog output signal into the analog data stream. Timing recovery can be accomplished by digital control of a phase interpolator or delay locked loop that receives a plurality of phases from a timing circuit coupled to receive a clock signal.