Nec Corporation

Nippon Electric Co., Ltd.

The Tokyo Electric Power Company, Incorporated

Nec Corporation and the Tokyo Electric Power Company, Incorporated

Shigeo Fushimi

Tadashi Kobayashi

Toshio Takagi

Hidetake Nakamura

Masatoshi Komatsu

Shigenori Wada

Takaya Watanabe

Masao Sato

Seiya Shida

In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals.

Meter for accurately measuring integrated electric power

In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals. As a further alternative, the meter comprises a first inverter for inverting a selected one of the first and the second input signals into a first inverted signal. In this event, a first selector alternatingly selects one of the first inverted signal and the selected one of the first and the second input signals and the other of the first inverted signal and the selected one of the first and the second input signals at a predetermined time interval as a first selected signal. A second inverter for inverting a product signal representing a product of the first and the second digital signals into a second inverted signal. Ganged with the first selector, a second selector alternatingly selects one of the second inverted signal and the product signal at the predetermined time interval as a second selected signal so that the second inverted signal is selected when the first selector selects the first inverted signal.

In a three-transducer surface acoustic wave device, an apodized electrode member is interposed between two interdigital electrode members, each having first and second ends and comprising interdigital electrodes between the first and the second ends either with a uniform density distribution or with a density distribution varied according to a prescribed rule of selective withdrawal of the interdigital electrodes. The apodized electrode member has first and second extremities and is given substantially minimum-phase and maximum-phase impulse responses for surface acoustic waves which are propagated either into or out of the apodized electrode member through one and the other of the extremities. Alternatively, an interdigital electrode member is interposed between two apodized electrode members. Each of the interdigital and the apodized electrode members is of the type described above. One of the apodized electrode member should have a substantially minimum-phase impulse response. The other should have a substantially maximum-phase impulse response.

Three-transducer saw device including one or two apodized transducers

A surface acoustic wave (SAW) filter has a piezoelectric substrate and a conductive transducer formed over the substrate. The transducer has first and second bus bars arranged in parallel at a prescribed interval from each other, a plurality of pairs of first electrode fingers having the same lengths, and a plurality of pairs of second electrode fingers having the same lengths. The tips of the second electrode fingers are positioned opposite those of the first electrode fingers. The transducer also has first and second weighted electrode pairs positioned between two adjacent pairs of the first electrode fingers and two adjacent pairs of the second electrode fingers, respectively. Each pair of first weighted electrodes has a pair of first electrode sections whose lengths of overlap with the paired second electrode fingers are determined by the negative tap coefficients of an FIR filter having a desired low pass characteristic and a pair of second electrode sections positioned on the elongations of these first electrode sections, one end of each such second electrode section been connected to the first bus bar. The second weighted electrode pairs are similarly formed, but the lengths of overlap are determined by the positive tap coefficients of the FIR filter.

Surface acoustic wave filter

A frequency division multiplexing system is disclosed having a plurality of individual modulators which modulate respective modulating signals onto respective carrier frequencies. The carrier frequencies are selected to have a frequency separation so that when modulated signals are combined, significant parts thereof do not overlap in frequency. The combined modulated signals are filtered by comb filters which suppress portions of the frequency spectra intermediate the significant portions.

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Tokyo, Japan

Shigeo Fushimi