An access control device according to one embodiment includes an access control mechanism, a housing, an antenna array secured within the housing and including a first, second, and third antenna adapted to radiate away from the exterior side of the door, a processor, and a memory. The memory includes a plurality of instructions that, when executed, causes the access control device to determine signal strengths of signals received by the first, second, and third antennas from the mobile device, determine whether a location of the mobile device relative to the access control device is indicative of the mobile device user's intent to access the passageway based on the signal strengths, and automatically unlock the access control mechanism in response to the location being indicative of the user's intent to access the passageway.

A system that is capable of controlling multiple entertainment systems and/or speakers using voice commands. The system receives voice commands and may determine audio sources and speakers indicated by the voice commands. The system may generate audio data from the audio sources and may send the audio data to the speakers using multiple interfaces. For example, the system may send the audio data directly to the speakers using a network address, may send the audio data to the speakers via a voice-enabled device or may send the audio data to the speakers via a speaker controller. The system may generate output zones including multiple speakers and may associate input devices with speakers within the output zones. For example, the system may receive a voice command from an input device in an output zone and may reduce output audio generated by speakers in the output zone.

A high-frequency transmission line is provided that improves a high-frequency characteristic. The high-frequency transmission line includes a first conductor line, a termination resistance connected to the first conductor line, a second conductor line connected to the termination resistance, and a ground line that is provided to be opposed to the first conductor line, the termination resistance, and the second conductor line to have a predetermined distance thereto and that is connected to the second conductor line. The first conductor line and the ground line are formed to have a line width decreasing toward the termination resistance, respectively.

A high-frequency transmission line is provided that improves a high-frequency characteristic. The high-frequency transmission line includes a first conductor line, a termination resistance connected to the first conductor line, a second conductor line connected to the termination resistance, and a ground line that is provided to be opposed to the first conductor line, the termination resistance, and the second conductor line to have a predetermined distance thereto and that is connected to the second conductor line. The first conductor line and the ground line are formed to have a line width decreasing toward the termination resistance, respectively.

A system for coupling a modulated voltage signal onto a current loop between a host device and a field device, in various embodiments, can include a circuit and an impedance bridge. The circuit is configured to flow current from the field device between two terminals of an input circuit in the host device, wherein the two terminals are included in the current loop. The impedance bridge is positioned between the two terminals and configured to modulate impedance to convert the current in a field loop produced by the field device into terminal voltage modulation, without introducing a DC voltage burden to the current.

A system for coupling a modulated voltage signal onto a current loop between a host device and a field device, in various embodiments, can include a circuit and an impedance bridge. The circuit is configured to flow current from the field device between two terminals of an input circuit in the host device, wherein the two terminals are included in the current loop. The impedance bridge is positioned between the two terminals and configured to modulate impedance to convert the current in a field loop produced by the field device into terminal voltage modulation, without introducing a DC voltage burden to the current.

Apparatuses, systems, and associated methods are described that provide signal transmission over copper media. An example module includes a number of electrical signal generators that each generate an electrical signal, and a signal modulation system that receives the electrical signals generated by the electrical signal generators. The signal modulation system further modulates each of the electrical signals such that each modulated electrical signal is distinguishable from the other modulated electrical signals. The module further includes an active copper multiplexer in electrical communication with the electrical signal generators that receives the modulated electrical signals from the signal modulation system. The active copper multiplexer further combines the multiple modulated signals into a single combined electrical signal and transmits the single combined electrical signal through a single copper cable.

A communication circuit for communication over a voltage isolation barrier, the communication circuit including a pulse driven transformer coupled to a current sensing input, wherein information is transferred in the current domain and wherein during the information transfer, the receiver input is made low ohmic, a current pulse transformer including a primary winding, a core, and a secondary winding, a resistor in parallel with the secondary winding, a current sensor having a low ohmic input to receive a pulse from the secondary winding, and a signal processing unit to extract information from the received pulse.

A communication circuit for communication over a voltage isolation barrier, the communication circuit including a pulse driven transformer coupled to a current sensing input, wherein information is transferred in the current domain and wherein during the information transfer, the receiver input is made low ohmic, a current pulse transformer including a primary winding, a core, and a secondary winding, a resistor in parallel with the secondary winding, a current sensor having a low ohmic input to receive a pulse from the secondary winding, and a signal processing unit to extract information from the received pulse.

An apparatus for generating a substantially constant DC reference voltage. The apparatus includes a reference voltage generator configured to generate a substantially constant direct current (DC) reference voltage based on a voltage on a data signal transmission line, wherein the voltage is based on a bandgap reference voltage. In one implementation, the data signal transmission line is a differential signal transmission line and the voltage is a common mode voltage. In another implementation, the data signal transmission line is an I-data signal transmission line and a Q-data signal transmission line, and the voltage is an average or weighted-average of the common mode voltages of the I- and Q-differential signals. In another implementation, the reference voltage is based on a single-ended (e.g., positive- and/or negative)-component or vice-versa of I- and Q-data signals, respectively.