Abstract: A system that measures a high electric voltage on an electrical transmission line has an electro optical voltage transducer sensor connected between the electrical transmission line and ground for providing in response to the measured high electric voltage a Sin optical intensity signal and a Cos optical intensity signal. The system also has a signal processor that operates in a first state to digitally process samples of the Sin and said Cos optical intensity signals. The process samples are used to provide a representation of the high electric voltage on the transmission line. The representation can be used for one or more of metering, relaying and transient capture.

Abstract: A system that measures a high electric voltage on an electrical transmission line has an electro optical voltage transducer sensor connected between the electrical transmission line and ground for providing in response to the measured high electric voltage a Sin optical intensity signal and a Cos optical intensity signal. The system also has a signal processor that operates in a first state to digitally process samples of the Sin and said Cos optical intensity signals. The process samples are used to provide a representation of the high electric voltage on the transmission line. The representation can be used for one or more of metering, relaying and transient capture.

Abstract: A digital controller time multiplexes dithering of the microwave frequency control signal and a laser wavelength control signal in a miniaturized cesium vapor atomic frequency standard. A unique common charge/sample and dump integrator amplifies the photodetector output for the + and - dither of both the laser current and microwave frequency. To suppress error in the integrated photodetector output attributable to noise generated by the digital processor, the processor is placed in a sleep mode during the integration intervals. To further suppress errors, the cesium vapor electric heaters are not energized during the intervals when the microwave signal is being dithered.

Abstract: In a communication and control system, an improved interface between a digital IC and its associated microcomputer is provided wherein a serial shift register in the digital IC is used to store the message bits of a received message and control of the shift register is transferred to the associated microcomputer as soon as the interface is set up so that data stored in the register is not overwritten by another received message. A busy signal is also supplied over one line of the interface only during periods when the digital IC is actually receiving or transmitting a message.

Abstract: The offset in digital samples of the voltages and currents in a power transmission system following a fault is reduced by subtracting a linear approximation of the exponential component of the transient from the magnitude of the samples to extract the sinusoidal component. The slope and initial ordinate value of the linear approximation are derived from simple calculations using pairs of digital samples spaced one-half cycle apart. Compensated values of the digital samples for the first half cycle of the transient are produced within one-half cycle plus one additional sampling interval from fault inception.

Abstract: A low cost, multipurpose digital IC is used as the basic building block in establishing a network communication system over a desired communication link. The digital IC can function as an addressable microcomputer interface between the network line and a remotely located microcomputer which may, for example, comprise any microprocessor based controlled product. In such mode, the digital IC's function is to take data from the network and pass it on to the remotely located microcomputer upon command from the central controller and to transmit data from the microcomputer to the central controller. The digital IC may also function as a nonaddressable microcomputer interface between the central or master controller and the network line. In such case the digital IC's function is to continuously take data from the central controller and place it on the network and take data from the network and pass it back to the central controller.

Abstract: Apparatus for measuring current over a wide range generates an eight bit accurate, 16-bit dynamic range digital signal from a current transformer secondary. Two signals proportional to the rectified secondary current, one generated by a large burden resistor and the other by an amplifier with programmable gain and an overrange indication, are applied through a multiplexer to an eight bit analog to digital converter which has three selectable reference voltages. A microprocessor selects the input signal, converter reference voltage, and one of four levels of amplifier gain which provide the greatest resolution for the magnitude of the current being measured, and provides an appropriate scale factor, from 2.sup.0 to 2.sup.8, for the eight bit accurate digital signal generated by the analog to digital converter.

Abstract: In polyphase systems with a set of waveforms, such as a three-phase power system, each waveform is Fourier analyzed for a frequency component: A single sample/hold circuit samples each waveform sequentially, and the sampling time difference is compensated by adjusting the sampled values to a common time-point, using vector rectangular coordinate sine/cosine processing.

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: A programmed overexcitation protective relay with selectable time-overexcitation operation to govern the interruption of energy to a piece of power equipment, like a transformer, generator or the like. A programmed processor is included to derive an overexcitation time-to-trip in accordance with sampled measurement voltage values of at least one power line supplying energy to the power equipment being protected, 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 overexcitation 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 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: 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.