Abstract: A semiconductor switch including a plurality of die assembled hybrid circuit packages. Each package includes a relatively large number of parallely connected semiconductor switch devices, more particularly metal oxide semiconductor field effect transistors (MOSFETs). An active snubber circuit is connected to the MOSFETs in order to remove the requirement for current sharing during circuit interruption where the MOSFETs turn-off. Each MOSFET package furthermore includes metallic arc barriers between MOSFETs to prevent an arc from propagating from one failed MOSFET to neighboring MOSFETs. Also all of the MOSFETs are turned on momentarily to extinguish arcs whenever the semiconductor switch is in an open or non-conducting condition and a current flow is detected. Clamping of the gate electrode drive bus of the MOSFETs is additionally provided to ensure fusing of gate bonding wires coupling the gate electrodes of the respective MOSFETs to the gate drive bus.

Abstract: A dual mode electronic identification system using a tag which has a RF receiver and transmitter contained therein. In the first mode the tag responds to an interrogation signal by transmitting identification data to the interrogator. In the second mode the tag periodically transmits an identification beacon signal to a directional sensing antenna which uses the signal to compute the position of the tag. The power supply for the tag operates from an internal battery or from power received from a portal signal via a tag receiving antenna. The battery can be automatically turned off when the tag is in the portal area and the unit can be shifted into the battery operated beacon mode when the tag is removed from the portal area.

Abstract: An electronic identification tag interrogation method is provided in which a portal transmits an interrogation signal which is received by an electronic identification tag within its field of range. The interrogation signal includes an address which requests a response from every tag having an address greater than or equal to the address of the signal. If more than one reply is received by the portal, the interrogation address is bisected and the interrogation signal is retransmitted. The interrogation address is successively bisected until a single response is isolated. When a single response is isolated, communication is directed between the portal and the identification tag and the interrogation system is reset to isolate and identify any remaining tags.

Abstract: A pulse width modulation (PWM) control circuit provides for improved implementation of position, velocity and current feedback loops for digital servo control of a multi axis robot. The PWM circuit utilizes a single resistor for sensing joint motor drive current. Circuitry is also disclosed for reducing audible noise and motor heating in large servo motors used for joint arms operated at relatively low PWM frequencies by reducing the motor ripple current.

Abstract: A method for transmitting data in the form of a sequence of data words according to PLBus communications protocol in a channel (20) carrying data transmitted, according to a different protocol, in the form of timed bursts of a signal, comprising: producing (16) a carrier which is continuous at least for the duration of each data word; angularly modulating (14, 16) the carrier in accordance with the information contained in each data word; and transmitting the angularly modulated carrier in the channel (20).

Abstract: A light driven remote system and power supply therefor that includes a laser diode that provides pulses of light to a fiber optic cable. The pulses of light are detected by a remote photodiode that is connected in parallel with a step-up transformer. The output of the step-up transformer is filtered to provide power for a remote system. Data transmission from the remote system is synchronized with transmission of light to the photodiode.

Abstract: A digital control for a multiaxis robot includes position, velocity and torque controls that drive a motor voltage control loop. Pulse width modulated control signals operate power switches in a power bridge to control the current to each robot joint motor. A single resistor is connected in the bridge circuit to supply motor current feedback needed for control loop operation.

Abstract: A method of mapping addresses of a plurality of refrigerated containers having remote monitoring units (RMUs) connected to a power line carrier based monitoring system which includes a master monitoring unit (MMU). The method adapts to the size of the expected number of containers to be mapped by any mapping command, to reduce the overall time to map either a large or small number of containers. The method includes the MMU selecting a modulo having a magnitude determined by the number of containers expected to be mapped, and the RMUs generating a random number within the range responsive to the modulo. The RMUs apply response messages to the power line, which include the addresses of the associated containers, at a time responsive to the magnitude of the random number.

Abstract: A power line carrier communication system for monitoring refrigerated containers which includes a master monitoring unit and a first power line interface which interchange messages in a first format. The first power line interface translates the first format to a second format suitable for power line environment, and messages in the second format are applied to a power line. Remote monitoring units receive the messages from the power line, and they return messages to the power line containing status data relative to refrigerated containers. The second format includes a message starting preamble having a duration and logic level which is not duplicated by normal operation of the apparatus, enhancing the probability of proper message synchronization and reception over noisy power line environments.

Abstract: A completely digital robot control operates at a predetermined sampling rate. The robot arm has a plurality of joints with each driven by an electric brushless or brush-type DC motor which is in turn supplied with drive current by a power amplifier bridge circuit having power switches connected therein to supply motor winding current in the forward or reverse direction.Incremental or absolute encoders and tachometers provide for generating digital position and velocity feedback signals generated synchronously with the sampling rate. Digital motor current feedback signals are also generated synchronously with the sampling rate.Paired position/velocity microprocessors generate torque commands for each of the robot axes at the sampling rate in response to the position commands and the position and velocity feedback signals. Paired torque microprocessors generate motor voltage commands for each of the robot axes at the sampling rate in response to the torque commands and the current feedback signals.

Abstract: Programmed overcurrent protection control apparatus with selectable time-overcurrent operation to govern the interruption of current through at least one power line associated with either a ground phase or a power phase of a power system network is disclosed. A programmed processor is included to derive an overcurrent time-to-trip in accordance with sampled measurement current values of the power line and selected derivation constants stored in a memory look-up table. The derivation constants are selected from the look-up table based on derivation parameters which may be set and read by the programmed processor from time to time. The programmed processor utilizes the selected derivation constants to derive the time-to-trip over a number of predetermined time intervals during which the overcurrent condition persists.

Abstract: An on-off keyed carrier signal is demodulated by quadrature sampling of the incoming carrier signal at twice carrier frequency to provide short term digital patterns indicating detection of an incoming signal of carrier frequency. A number of phase counting channels are provided which count the number of times a particular pattern is detected during a longer interval, preferably a sixth of a bit interval at the baud rate of the received message. Since the phase counters are reset every sixth of a bit they can collectively accommodate a substantial drift in phase of the received carrier during reception of a complete 33 bit message while still operating asynchronously with respect to the received carrier.

Abstract: An on-off keyed carrier signal is demodulated by quadrature sampling of the incoming carrier signal at twice carrier frequency to provide short term digital patterns indicating detection of an incoming signal of carrier frequency. A number of phase counting channels are provided which count the number of times a particular pattern is detected during a longer interval, preferably a sixth of a bit interval at the baud rate of the received message. Since the phase counters are reset every sixth of a bit they can collectively accommodate a substantial drift in phase of the received carrier during reception of a complete 33 bit message while still operating asynchronously with respect to the received carrier.

Abstract: A bidirectional coupling circuit is provided for carrier based communication and control networks in which a coupling transformer is employed having relatively decoupled primary and secondary windings which are each tuned to the carrier frequency. Separate secondary windings are wound on the same core leg, one of these secondary windings being employed as a transmitter winding which is referenced to a positive supply voltage and the other winding being employed as a receiver winding which is referenced to ground. The coupling transformer is arranged to have a relatively high input impedance at the carrier frequency but due to series resonant effects has a relatively low impedance for undesired signals on either side of the carrier frequency. An operational amplifier is connected to the receiver winding to provide high gain amplification for a signal received from the common network power line without loading the other windings of the transformer.

Abstract: An on-off keyed carrier signal is demodulated by quadrature sampling of the incoming carrier signal at twice carrier frequency to provide short term digital patterns indicating detection of an incoming signal of carrier frequency. A number of phase counting channels are provided which count the number of times a particular pattern is detected during a longer interval, preferably a sixth of a bit interval at the baud rate of the received message. Since the phase counters are reset every sixth of a bit they can collectively accommodate a substantial drift in phase of the received carrier during reception of a complete 33 bit message while still operating asynchronously with respect to the received carrier.

Abstract: A communication network digital message format is provided in which on message start signal has a logic "1" value for two bit intervals to provide improved noise immunity in transmission of a message over a network medium. The start signal is followed by a control bit one logic value of which designates a plurality of message bits as instruction bits to enable an interface to be set up between the network and a microcomputer, the other logic value of said control bit designating a plurality of message bits as data bits for the microcomputer after said interface has been established.

Abstract: A first input signal representative of the voltage component is integrated producing an integral signal. The integral signal is compared to fixed reference potentials. A second input signal representative of the current component is sampled when the instantaneous magnitude of the integral signal equals a reference potential. The sample value is digitized and the integrator is reset by variable width reset pulses. Successive sample values are accumulated producing totalized values representative of the time integral of the product of the current component and the time integral of the voltage component, or energy.

Abstract: Bidirectional addressable repeaters of a power line carrier communication system each include an address recognition and a receive and transmit control logic circuit having programmable zone and address identifying states for connection in plural repeating levels defining branch paths linking a central control terminal with multiple remote terminals via a distribution line network. Each repeater retransmits an interrogation message, provides its own repeater address modification, and remains in a response-wait status. The alerted repeaters define the predetermined route of branch paths for being sequentially activated by a response message. Simplified repeater response address formats are used and each repeater modified its address data upon response message retransmission. The desired sequentially occurring repeating transmissions are assured upon retransmission of both the interrogation and response messages.

Abstract: In a line scan camera system employed to extract information from marks or characters on a document, a memory circuit is used to store the average white and black video output from the camera so that a given white-to-black transition can be compared to adaptive white and black references to compensate for variations in document background light intensity and vignetting associated with the lens of the line scan camera system.

Abstract: A capacitive angular displacement transducer having a rotor plate and a first and second stator plates is disclosed. The rotor plate is coaxially mounted between, and parallel to, the first and second stator plates. The first stator plate is divided into four excitation areas each being impressed with a sinusoidal excitation voltage having a different phase angle. The rotor plate has a first face having two conductive patterns. The two conductive patterns act as resolvers to produce resultant voltages from the vector addition of the voltages variably capacitively coupled thereon due to the excitation voltages. The rotor plate has a second face having two annular conductive areas electrically connected to the conductive patterns of the first rotor face. The second rotor face together with the second stator plate form a constant capacitive pickup for the resultant voltages produced by the two conductive patterns of the first rotor face.