An apparatus includes a capacitor, a reference voltage, an input signal to be measured, and a frequency calculation circuit. The frequency calculation circuit is configured to select a capacitance value for the capacitor, charge the capacitor with the reference voltage, discharge the capacitor to a threshold voltage, and, based on a comparison of time to discharge the capacitor to the threshold voltage with a clock cycle of the input signal, determine a frequency of the input signal.

Provided is a sample inspection apparatus capable of identifying a capacitive fault or a potential faulty point where an electrical tolerance is low. The sample inspection apparatus includes: a charged particle optical system configured to irradiate a sample 19 with a charged particle beam; a first probe 21a configured to come into contact with the sample; an amplifier 23 having an input terminal to which the first probe is connected; and a phase detection unit 40 to which an output signal of the amplifier is input, in which an AC voltage is applied to the first probe, and the phase detection unit detects the output signal of the amplifier using a reference signal synchronized with the AC voltage and having the same frequency as the AC voltage.

Provided is a sample inspection apparatus capable of identifying a capacitive fault or a potential faulty point where an electrical tolerance is low. The sample inspection apparatus includes: a charged particle optical system configured to irradiate a sample 19 with a charged particle beam; a first probe 21a configured to come into contact with the sample; an amplifier 23 having an input terminal to which the first probe is connected; and a phase detection unit 40 to which an output signal of the amplifier is input, in which an AC voltage is applied to the first probe, and the phase detection unit detects the output signal of the amplifier using a reference signal synchronized with the AC voltage and having the same frequency as the AC voltage.

A method for single-phase islanding detection in a three-phase electricity network, can include supplying power into a three-phase electricity network (EN) by a power supply assembly (PSA), the electricity network (EN) having a network voltage, and providing a stimulus signal into a positive sequence electric quantity of the electricity network, the positive sequence electric quantity being current, power or a derived quantity thereof. A magnitude and/or a rate of change of an indicative element of a negative sequence component of the network voltage is monitored, a frequency domain of the indicative element including a frequency corresponding to the stimulus signal. A single phase islanding condition is detected in the electricity network (EN) if the magnitude and/or rate of change of the indicative element exceeds a predetermined limit value.

A method for detecting high-frequency signals, comprising: dividing a high-frequency signal into a raw signal and a reference signal; attenuating the raw signal into an attenuated signal, wherein the attenuating happens as a function of frequency of the raw signal in accordance with an attenuation characteristic; rectifying the attenuated signal, so that a first direct voltage is generated; rectifying the reference signal, so that a second direct voltage is generated; ascertaining an attenuation from the ratio of the first and second direct voltages, wherein the ratio corresponds to an attenuation factor for the attenuation of the raw signal; and determining the frequency of the high-frequency signal from the attenuation factor and an attenuation characteristic.

A method for detecting high-frequency signals, comprising: dividing a high-frequency signal into a raw signal and a reference signal; attenuating the raw signal into an attenuated signal, wherein the attenuating happens as a function of frequency of the raw signal in accordance with an attenuation characteristic; rectifying the attenuated signal, so that a first direct voltage is generated; rectifying the reference signal, so that a second direct voltage is generated; ascertaining an attenuation from the ratio of the first and second direct voltages, wherein the ratio corresponds to an attenuation factor for the attenuation of the raw signal; and determining the frequency of the high-frequency signal from the attenuation factor and an attenuation characteristic.

Filter circuitry is constituted by transversal filters which are connected in parallel to each other. The transversal filters change amplitude and a phase of an input digital signal X.sub.in[n.Math.T.sub.s] and output different digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] as respective resulting digital signals whose amplitude and phase have been changed. A phase frequency computer computes a phase .sub.X[n.Math.T.sub.s] and a frequency f.sub.X[n.Math.T.sub.s] of the input digital signal X.sub.in[n.Math.T.sub.s] by performing phase computation and frequency computation using the digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] output by the transversal filters.

Filter circuitry is constituted by transversal filters which are connected in parallel to each other. The transversal filters change amplitude and a phase of an input digital signal X.sub.in[n.Math.T.sub.s] and output different digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] as respective resulting digital signals whose amplitude and phase have been changed. A phase frequency computer computes a phase .sub.X[n.Math.T.sub.s] and a frequency f.sub.X[n.Math.T.sub.s] of the input digital signal X.sub.in[n.Math.T.sub.s] by performing phase computation and frequency computation using the digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] output by the transversal filters.

A physical quantity measurement apparatus includes a first resonator, a second oscillator, and an integrated circuit device. The integrated circuit device includes a first oscillation circuit that causes the first resonator to oscillate, and thus generate a first clock signal having a first clock frequency, a second oscillation circuit that causes the second oscillator to oscillate, and thus generate a second clock signal having a second clock frequency which is different from the first clock frequency, and a measurement unit that is provided with a time-to-digital conversion circuit which converts time into a digital value by using the first clock signal and the second clock signal.

Given a node of a utility service distribution network, a topology of a subset of the distribution network having the given node as a root node and one or more child nodes branching from the given node is determined. The topology may be determined based on relationships or correlations of utility usage information between the given node and a plurality of potential nodes that are considered in the topology determination. Upon determining the topology associated with the given node, the determined topology may be used to detect fraud and leakage that may occur in the distribution network on a regular basis or upon request. If fraud or leakage is detected in the distribution network, the system may schedule a follow-up and/or field investigation to investigate and fix the fraud or the leakage in the distribution network.