Abstract: An electronic shelf label with a modulated backscatter communication system which can actively transmit signals. The electronic shelf label includes a modulated backscatter receiver for receiving a first modulated radio frequency (RF) carrier signal, and a transmitter powered by the first modulated RF carrier signal for transmitting a second modulated RF carrier signal.

Abstract: A wireless data communication system is operable in a power saving mode wherein stations are synchronized to be in an awake state to receive synchronizing messages (TIM, PSYNC) and traffic indicator information and are changed to a doze state if they are not to receive data messages. In one embodiment all stations (20) communicate via a base station access point (16), which broadcasts synchronizing messages (TIM) at regular intervals identifying stations (20) that are to receive data messages. In another embodiment all stations (220) communicate directly with one another, one station assumes the role of a master station and broadcasts synchronizing messages (PSYNC), and stations (220) desiring to transmit data messages transmit traffic indicator messages (PTIM) to the appropriate destination stations (220), in a synchronized awake period just before the next synchronizing message (PSYNC) is expected to arrive.

Abstract: An adaptive hybrid circuit is disclosed for adaptively cancelling a crosstalk component from a transmitter to a receiver in a local station of a local area network. In a preferred embodiment the adaptive hybrid circuit is coupled to a common two-wire transmission line in the network and also between the transmitter and the receiver of the local station. The adaptive hybrid circuit is comprised of a comparator, an integrator and an adjustment circuit. An output signal from the receiver is compared in the comparator with a transmit signal to develop a first signal which causes the integrator to develop a second signal having an amplitude which varies as a function of the states of the first signal. The second signal from the integrator, a transmitter signal, and a composite signal from the transmission line containing a crosstalk component from the transmitter and a received signal component transmitted from a remote station are applied to the adjustment circuit.

Abstract: In a local area network having a plurality of stations coupled to a transmission line over which signals are being simultaneously transmitted and received and wherein each station includes a station controller, a transmitter, a receiver and an adaptive hybrid circuit coupled to the transmission line and between the transmitter and the receiver for adaptively cancelling crosstalk from the transmitter to the receiver, a control circuit in each station for controlling the operation of the adaptive hybrid circuit in the station. In a first embodiment of the invention the control circuit includes a first circuit responsive to a request-to-send signal from the station controller for generating a first signal to enable a signal to be transmitted by the transmitter, and a second circuit responsive to the first signal for enabling the adaptive hybrid circuit to adaptively cancel crosstalk from the transmitter to the receiver after a preselected period of time after the start of each transmission.

Abstract: A wireless data communication system is operable in a power saving mode wherein stations are synchronized to be in an awake state to receive synchronizing messages (TIM, PSYNC) and traffic indicator information and are changed to a doze state if they are not to receive data messages. In one embodiment all stations (20) communicate via a base station access point (16), which broadcasts synchronizing messages (TIM) at regular intervals identifying stations (20) that are to receive data messages. In another embodiment all stations (220) communicate directly with one another, one station assumes the role of a master station and broadcasts synchronizing messages (PSYNC), and stations (220) desiring to transmit data messages transmit traffic indicator messages (PTIM) to the appropriate destination stations (220), in a synchronized awake period just before the next synchronizing message (PSYNC) is expected to arrive.