Abstract: This invention teaches new types of linearization circuits, exhibiting improved broadband suppression of nonlinear distortion. These realizations do not require the use of reactive elements such as capacitors, or of active elements such as transistors, eliminating the drawbacks of prior art realizations. The linearization circuits are particularly suitable for linearizing optical sources with odd wave voltage to light transfer characteristics, such as externally modulated CW lasers. The fundamental building blocks of the linearization circuits of this invention are novel nonlinear electrical one-ports with an expansive V-I characteristic, denoted as ENLOP (Expansive Nonlinear one-Ports). The ENLOP building blocks are further embedded in linear circuits.

Abstract: A monostable circuit of a voltage-to-frequency converter supplies feedback pulses to balance the input signal to a first integrator. These same pulses are supplied to a second integrator where they are compared with reference pulses from a crystal-controlled clock. Any drift in the pulse-width of the feedback pulses is corrected by a control signal applied to the monostable circuit by the second integrator to vary its quasi-stable period appropriately. Thus the precision of the converter is improved without disturbing its asynchronous properties.

Abstract: An electronic watthour meter for connection in a two-wire power distribution circuit comprises a shunt connected in one of the wires and an electronic circuit comprising a transconductance multiplier, a V to F converter and a reversible counter. The DC power supply of the electronic circuit is referred to the wire containing the shunt, which wire is always live, so that the electronic circuit "floats" electrically on this live wire. The first input of the multiplier can therefore be directly connected across the shunt, and the second input is connected via a high value resistance to the other wire so as to receive an input current representative of the voltage between the wires. To eliminate the effects of drift in the multiplier, the polarity of the input current to the multiplier and the direction of counting of the counter are periodically and simultaneously reversed by a square wave signal of 1:1 mark space ratio. The electronic circuit is implemented using LSI techniques.

Abstract: An electricity meter for metering the amount of electrical energy supplied by a power supplier to a power consumer is provided with fraud detection means for detecting the presence of an external shunt which has been connected to by-pass its internal current sensing means. The detection means, which comprises a differential current sensor for sensing the difference between the respective currents flowing to and from the consumer via the meter and a multiplier for multiplying this current difference by a signal derived from the supply voltage, is arranged to operate a circuit breaker, and/or to compensate the energy measurement of the meter, and/or to provide a warning to the supplier. The differential current sensor also senses when current is being taken between the live wire and earth on the consumer's side of the meter.

Abstract: An electronic watthour meter for connection in a two-wire power distribution circuit comprises a shunt connected in one of the wires and an electronic circuit comprising a transconductance multiplier, a V to F converter and a reversible counter. The DC power supply of the electronic circuit is referred to the wire containing the shunt, which wire is always live, so that the electronic circuit "floats" electrically on this live wire. The first input of the multiplier can therefore be directly connected across the shunt, and the second input is connected via a high value resistance to the other wire so as to receive an input current representative of the voltage between the wires. To eliminate the effects of drift in the multiplier, the polarity of the input current to the multiplier and the direction of counting of the counter are periodically and simultaneously reversed by a square wave signal of 1:1 mark space ratio. The electronic circuit is implemented using LSI techniques.

Abstract: A waveform to be analyzed is repetitively sampled at corresponding instants in each of several cycles, and the samples from each cycle for a respective instant summed to derive an average value for that instant in one cycle of the waveform. The average values are then used for Fourier transform analysis, either by mathematical manipulation or by sequential correlation. The timing of the samples is determined by counting pulses from a high-frequency clock for one cycle of the waveform, truncating the count to remove the n least significant digits, and taking a sample every time a number of pulses equal to the truncated count has occurred (resulting in 2.sup.n samples per cycle for a modulo 2 counter).

Abstract: A remotely-controllable relay which is controlled by 175 Hz ripple voltage superimposed on the mains supply voltage in an electric-power distribution network contains an oscillator generating a signal at 173 Hz. This is mixed with the network voltage so that, when ripple voltage is present, a beat note at a frequency of 2 to 3 Hz is generated. This beat note is separated from the unwanted signals, such as the mains supply voltage, by a third order active low-pass filter to control operation of the relay. A similar technique provides simplified detection of output signals from correlation-type filters.