A circuit apparatus is a circuit apparatus used for a physical quantity measuring apparatus, including a detection circuit that performs physical quantity detection processing based on a detection signal from a physical quantity transducer and a processing circuit that performs processing based on an output signal of the detection circuit. The processing circuit obtains index information of floor noise generated in the detection circuit based on the output signal and performs abnormality detection of the physical quantity measuring apparatus based on the index information.

A circuit apparatus is a circuit apparatus used for a physical quantity measuring apparatus, including a detection circuit that performs physical quantity detection processing based on a detection signal from a physical quantity transducer and a processing circuit that performs processing based on an output signal of the detection circuit. The processing circuit obtains index information of floor noise generated in the detection circuit based on the output signal and performs abnormality detection of the physical quantity measuring apparatus based on the index information.

Methods and devices for switching filters and medical apparatuses using the same are described. The method includes: detecting whether or not a frequency range of an input signal is changed from a first frequency range into a second frequency range; if changed, switching from a first filter to a second filter, and taking a sample value of the input signal at a current moment as an input value of the second filter at the current moment and sample values of the input signal at n moments before the current moment as input values of the second filter at the n moments, respectively, and taking output values of the first filter at m moments before the current moment as output values of the second filter at the m moments, to obtain an output value of the second filter at the current moment.

Methods and devices for switching filters and medical apparatuses using the same are described. The method includes: detecting whether or not a frequency range of an input signal is changed from a first frequency range into a second frequency range; if changed, switching from a first filter to a second filter, and taking a sample value of the input signal at a current moment as an input value of the second filter at the current moment and sample values of the input signal at n moments before the current moment as input values of the second filter at the n moments, respectively, and taking output values of the first filter at m moments before the current moment as output values of the second filter at the m moments, to obtain an output value of the second filter at the current moment.

A method and apparatus to compensate for distortion of a waveform due to the skin effect in a current shunt. The method includes modeling the complex impedance of the shunt as component complex impedances. By designing a filter corresponding to the component complex impedances, the distortion of a waveform across the shunt may be reversed to provide an accurate replica of the undistorted waveform.

An RF signal detection device, including: a first threshold crossing detection circuit comprising an input coupled to an input of the RF signal detection device; a first energy detection circuit comprising an input coupled to the input of the RF signal detection device; a second threshold crossing detection circuit comprising an input coupled to an output of the first energy detection circuit; and further including a control circuit configured to: carry out, by the first threshold crossing detection circuit, detection of at least a first threshold crossing frequency in a predetermined RF frequency band; and carry out, by the first energy detection circuit, energy detection in the predetermined RF frequency band; and carry out, by the second threshold crossing detection circuit, detection of at least a second threshold crossing frequency of a first energy signal delivered as an output from the first energy detection circuit; and determine, at least from the first and second threshold crossing frequencies and the first energy signal, whether a single RF signal is present in the RF frequency band.

A method and an apparatus for detecting a vector shift in an AC power system, the apparatus comprising frequency measuring means adapted to determine a frequency of the AC power system, derivation means adapted to determine a time derivative of the frequency, filtering means adapted to filter the time derivative of the frequency, and detection means adapted to calculate time derivatives for the filtered time derivatives of the frequency over a time period having the length of the fundamental period of the AC power system, to determine a number of positive and negative time derivatives among the calculated time derivatives, and to detect a vector shift in the AC power system in response to an absolute value of a difference between the determined number of positive time derivatives and negative time derivatives exceeding a predetermined threshold value.

A method and an apparatus for detecting a vector shift in an AC power system, the apparatus comprising frequency measuring means adapted to determine a frequency of the AC power system, derivation means adapted to determine a time derivative of the frequency, filtering means adapted to filter the time derivative of the frequency, and detection means adapted to calculate time derivatives for the filtered time derivatives of the frequency over a time period having the length of the fundamental period of the AC power system, to determine a number of positive and negative time derivatives among the calculated time derivatives, and to detect a vector shift in the AC power system in response to an absolute value of a difference between the determined number of positive time derivatives and negative time derivatives exceeding a predetermined threshold value.

Embodiments are described of devices and methods for processing a signal using a plurality of vector signal generators (VSGs). A digital signal may be provided to a plurality of signal paths, each of which may process a respective frequency band of the signal, the respective frequency bands having regions of overlap. The gain and phase of each signal path may be adjusted such that continuity of phase and magnitude are preserved through the regions of overlap. The adjustment of gain and phase may be accomplished by a complex multiply with a complex calibration constant. The calibration constant may be determined for each signal path by comparing the gain and phase of one or more calibration tones generated within each region of overlap. Each signal path may comprise a VSG to convert the respective signal to an analog signal, which may be combined to obtain a composite signal.

There is provided a broadband lossless partial discharge detection and noise removal device which includes: a partial discharge occurrence timing pulse acquiring unit acquiring a generated timing pulse of a partial discharge signal at the beginning of generation of a partial discharge signal; a partial discharge magnitude pulse acquiring unit acquiring a magnitude pulse of the partial discharge signal; a synchronization comparing unit detecting a partial discharge digital signal determined according to whether the generated timing pulse of the partial discharge signal and the magnitude pulse are synchronized; and a partial discharge signal generating unit detecting a partial discharge pulse obtained by converting the detected partial discharge digital signal into an analog signal.