Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1995-09-12
1998-06-16
Brock, Michael
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
73861356, G01R 2500, G01F 184
Patent
active
057676658
ABSTRACT:
A phase difference measuring apparatus for accurately measuring the phase difference (fine time difference) of two signals with the same frequency with a reduced number of bits for A/D conversion is disclosed. In addition to output signals of an upstream side pickup and a downstream side pickup of a mass flowmeter, an output signal of the upstream side pickup or the downstream side pickup is supplied to a comparator, a PLL circuit, an antialiase filter, a sample and hold circuit, and an A/D converter. These circuits quantize these signals and send the quantized signals to a band pass filter. The band pass filter extracts a predetermined signal component and outputs it to a DFT. The DFT performs complex Fourier transformation on the input signal. Thus, the phase difference between two signals with the same frequency (such as an upstream side pickup signal and a downstream side pickup signal) can be accurately detected with a reduced number of bits for each of the A/D converters.
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patent: 5469758 (1995-11-01), Kalotay
Morita Akira
Yoshimura Hiroyuki
Brock Michael
Fuji Electric & Co., Ltd.
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