The invention provides for a network power-supply voltage adaptor arranged to receive an input voltage (V in) from a network trunk cable and to present an internal voltage derived from the said input voltage (V in), the adaptor being arranged, when at least one of the input voltage (V in) or the said internal voltage is above a reference voltage (Ref V), to regulate the received input voltage (V in) to provide an adaptor output dc power supply voltage (V out) at a substantially constant dc power supply level less than that of the input voltage (V in), and independent of changes in the input voltage level (V in), and the adaptor further comprising at least one communication feed-through loop (55, 56, 66, 68) for the passage of substantially unaltered communications signals through the adaptor.

A coupling circuit for power line communications includes a coupling transformer having first and second mutually coupled windings, with the first winding connectable to a power line. The second winding includes a pair of intermediate taps with one or more tuning inductor therebetween. The inductor or inductors are set between a first portion and a second portion of the second winding of the coupling transformer. A switch member is provided coupled with the inductor. The switch member is selectively actuatable to short-circuit the inductor.

Aspects of the subject disclosure may include, receiving a signal, and launching, according to the signal, an electromagnetic wave along a transmission medium, where the electromagnetic wave propagates along the transmission medium without requiring an electrical return path, and where the electromagnetic wave has a phase delay profile that is dependent on an azimuth angle about an axis of the transmission medium. Other embodiments are disclosed.

Aspects of the subject disclosure may include, a system that can be configured for generating an electromagnetic wave and coupling the electromagnetic wave to a transmission medium with a reduced loss of radiation of the electromagnetic wave into free space. The system can also be configured to receive an electromagnetic waves form the transmission medium with a reduced loss of radiation of the electromagnetic wave into free space. Other embodiments are disclosed.

A circuit (100) for coupling an amplifier (1) in an electrical power distribution system with the amplifier electrically and physically isolated from a power line of the system. The amplifier generates arbitrary signal waveforms injected into the power line. A transformer (T1) has a primary and a secondary side with the amplifier located on the primary side and the secondary side connected to the power line. A resistor (R1) series connected with the primary side of the transformer is sized to accommodate a minimum load impedance of the amplifier and minimize power dissipation. A resonant circuit interposed between the secondary side of the transformer and the power line has values for a capacitor (C1) and an inductor (L3) forming the resonant circuit chosen to peak the amplitude of the arbitrary signal waveform at the frequency of a waveform propagated through the power line.

Aspects of the subject disclosure may include, for example, identifying a device coupled to a transmission medium that obstructs a propagation of guided electromagnetic waves propagating on an outer surface of the transmission medium when the device is subjected to a liquid, and applying a material to a portion of the device to mitigate the obstruction. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a waveguide including a plurality of devices that facilitate generating scattered electromagnetic waves from electromagnetic waves propagating on a surface of a transmission medium. The scattered electromagnetic waves combine to generate a wireless signal having a directionality based on a separation between plurality of devices and a wavelength of the electromagnetic waves. Other embodiments are disclosed.

A well tool for use in a wellbore can include a motor for performing a well operation. The well tool can include a switch that is couplable between the motor and a wireline. The switch can be toggleable between (i) a first operational state for providing the power to the motor by coupling the motor to an external power source and (ii) a second operational state for decoupling the motor from the external power source. The well tool can include a motor controller coupled to the switch for toggling the switch between the first operational state and the second operational state in an arrangement configured to impart, on the wireline, multiple current pulses including data encoded in the current pulses according to an encoding scheme.

An apparatus comprising a signal transformer coupled to a power line and a signal transmission, reception, or detection circuit. A sensor is configured to be responsive to the power line current or magnetic flux generated in a ferrite core of the signal transformer. When the sensor indicates that the flux generated by the power line current mat cause an attenuation of the signal strength, a second circuit generates a current through a flux cancelling winding that cancels at least some of the flux generated by the power line current.

A power line carrier fault detection system includes a forward signal generator configured to transmit a carrier signal to a power line. A directional coupler couples the forward signal generator to the power line. The directional coupler is configured to separate forward and reflected power. A frequency selective filter associated with the directional coupler is configured to meter frequencies within a band of a transmitted carrier signal and to attenuate out of band signals.