Methods for building, transmitting, and receiving frame structures in power line communications (PLC) are described. Various techniques described herein provide a preamble design using one or more symbols. One or more preamble symbols may be interspersed within a header portion of a PLC frame to facilitate estimation of a frame boundary and/or sampling frequency offset, for example, in the presence of impulsive noise.

Methods for building, transmitting, and receiving frame structures in power line communications (PLC) are described. Various techniques described herein provide a preamble design using one or more symbols. One or more preamble symbols may be interspersed within a header portion of a PLC frame to facilitate estimation of a frame boundary and/or sampling frequency offset, for example, in the presence of impulsive noise.

An air-conditioning apparatus includes a first transmission channel, a plurality of second transmission channels different from the first transmission channel, a controller connected to the first transmission channel and not connected to the second transmission channels, a plurality of air-conditioning indoor units connected to the second transmission channels and not connected to the first transmission channel, and a plurality of air-conditioning outdoor units. The plurality of air-conditioning outdoor units electrically connect the first transmission channel and the second transmission channels, and do not transmit a short-circuit state occurring in one of the first transmission channel and the second transmission channels to a transmission channel other than the one of the first transmission channel and the second transmission channels, thereby enabling communication between devices connected to the transmission channel other than the one.

An air-conditioning apparatus includes a first transmission channel, a plurality of second transmission channels different from the first transmission channel, a controller connected to the first transmission channel and not connected to the second transmission channels, a plurality of air-conditioning indoor units connected to the second transmission channels and not connected to the first transmission channel, and a plurality of air-conditioning outdoor units. The plurality of air-conditioning outdoor units electrically connect the first transmission channel and the second transmission channels, and do not transmit a short-circuit state occurring in one of the first transmission channel and the second transmission channels to a transmission channel other than the one of the first transmission channel and the second transmission channels, thereby enabling communication between devices connected to the transmission channel other than the one.

Methods for building, transmitting, and receiving frame structures in power line communications (PLC) are described. Various techniques described herein provide a preamble design using one or more symbols. One or more preamble symbols may be interspersed within a header portion of a PLC frame to facilitate estimation of a frame boundary and/or sampling frequency offset, for example, in the presence of impulsive noise.

Methods for building, transmitting, and receiving frame structures in power line communications (PLC) are described. Various techniques described herein provide a preamble design using one or more symbols. One or more preamble symbols may be interspersed within a header portion of a PLC frame to facilitate estimation of a frame boundary and/or sampling frequency offset, for example, in the presence of impulsive noise.

A communication system includes a first system input adapted to be coupled to a DC transient current transitioning between a starting level and a target level on a pseudo-sinusoidal path and incudes a second system input adapted to be coupled to a HART signal. The system includes an adder circuit having an output, a first adder input coupled to the first system input and a second adder input coupled to the second system input. The adder circuit provides a superimposed signal comprising the HART signal and the DC transient current.

A communication system includes a first system input adapted to be coupled to a DC transient current transitioning between a starting level and a target level on a pseudo-sinusoidal path and incudes a second system input adapted to be coupled to a HART signal. The system includes an adder circuit having an output, a first adder input coupled to the first system input and a second adder input coupled to the second system input. The adder circuit provides a superimposed signal comprising the HART signal and the DC transient current.

A PoDL system that uses a center-tapped transformer, for galvanic isolation of the PHY, has AC-coupling capacitors in series between the transmission wires and the transformer's secondary windings for blocking DC voltages generated by a PSE power supply. The center tap is conventionally connected to ground. As a result, one capacitor sees the full VPSE voltage across it, and the other capacitor sees approximately 0 V across it. Since the effective value of a ceramic capacitor significantly reduces with increasing DC bias voltages across it, the effective values of the capacitors will be very different, resulting in unbalanced data paths. This can lead to conversion of common mode noise and corrupt the data. To avoid this, a resistor divider is used to generate VPSE/2, and this voltage is applied to the center tap of the transformer. Therefore, the DC voltage across each capacitor is approximately VPSE/2, so their values remain equal.

A communication system includes a first system input adapted to be coupled to a DC transient current transitioning between a starting level and a target level on a pseudo-sinusoidal path and incudes a second system input adapted to be coupled to a HART signal. The system includes an adder circuit having an output, a first adder input coupled to the first system input and a second adder input coupled to the second system input. The adder circuit provides a superimposed signal comprising the HART signal and the DC transient current.