Abstract: A tamper detection system and method which uses a reader and one or more tags to detect tampering near a card reader slot or any other device subject to tampering. An example tamper detection method includes transmitting a signal to a tag adjacent a device susceptible to tampering, and setting an alarm condition when no reply signal or an incorrect reply signal is received in response to the signal.

Abstract: A tamper detection system and method which uses a reader and one or more tags to detect tampering near a card reader slot or any other device subject to tampering. An example tamper detection method includes transmitting a signal to a tag adjacent a device susceptible to tampering, and setting an alarm condition when no reply signal or an incorrect reply signal is received in response to the signal.

Abstract: A low duty cycle wireless device is disclosed. The low duty cycle wireless device includes a high data rate transceiver, a low data rate receiver, and a microprocessor. The low data rate receiver receives a command to receive a large amount of information. The display information far exceeds the capacity for reception through the low data rate receiver. In response to the received command, the microprocessor wakes up from a sleep mode and activates the high data rate transceiver to receive the display information. The microprocessor deactivates the high data rate transceiver once the display information has been received.

Abstract: Systems and techniques for linking electronic shelf labels to and unlinking electronic shelf labels from a system. When a printed overlay for an electronic shelf label is prepared, a radiofrequency identification (RFID) tag is affixed as part of the overlay. The RFID tag provides an identifier associated with a product. When an ESL to which the overlay is affixed is to be linked, the RFID tag is read at substantially the same time the ESL is interrogated, and the product associated with the RFID tag identifier is associated with the ESL. When an ESL is to be unlinked, a communication including an identifier for the ESL is provided to a central data processor, with the communication having characteristics indicating that the ESL is to be unlinked. When a communication is received from an ESL, the characteristics of the communication are evaluated to determine if the ESL is designated for unlinking.

Abstract: Systems and techniques for RFID communication using a frequency shift between uplink and downlink carrier frequencies achieved by digital processing of a baseband signal before radio frequency modulation of a carrier signal occurs. Generation of the carrier signal, and modulation of the carrier signal, is accomplished using digital techniques. A digital representation of a baseband signal is modulated to create a complex baseband signal multiplied by a negative frequency shift equal to a difference between downlink and uplink carrier frequencies. This signal undergoes analog to digital conversion and modulation by a carrier signal at an uplink frequency. The complex baseband signal includes in-phase and quadrature components. During uplink communication, the in-phase component of the complex baseband signal is replaced by a constant value. The quadrature component is replaced by a zero signal. During uplink communication, therefore, an umodulated carrier signal at an uplink frequency is generated.

Abstract: Systems and techniques for RFID communication using a frequency shift between uplink and downlink carrier frequencies achieved by digital processing of a baseband signal before radio frequency modulation of a carrier signal occurs. Generation of the carrier signal, and modulation of the carrier signal, is accomplished using digital techniques. A digital representation of a baseband signal is modulated to create a complex baseband signal multiplied by a negative frequency shift equal to a difference between downlink and uplink carrier frequencies. This signal undergoes analog to digital conversion and modulation by a carrier signal at an uplink frequency. The complex baseband signal includes in-phase and quadrature components. During uplink communication, the in-phase component of the complex baseband signal is replaced by a constant value. The quadrature component is replaced by a zero signal, During uplink communication, therefore, an umodulated carrier signal at an uplink frequency is generated.

Abstract: Techniques for determining the distance between an RFID radio transceiver and an RFID tag. An RFID reader interrogates or otherwise communicates with an RFID tag by transmitting a carrier signal to the tag. The RFID tag modulates the carrier signal with an information signal and returns a reflected carrier signal to the reader. The reader analyzes properties of the reflected carrier signal, computes values related to the reflected carrier signal, and uses known values related to the transmitted carrier signal and values obtained from analyzing and processing the reflected carrier signal to compute the distance between the RFID tag and the reader.