A method determines the frequency of an alternating input signal includes storing the input signal, sampling the input signal at a first sampling frequency, a first calculation and a first angular comparison of two phasors representing the input signal at two respective instants, as a function of the input signal sampled at the first sampling frequency, estimating the frequency of the input signal, and searching for a modification of frequency of the input signal. When a modification is detected the method includes, determining a second sampling frequency, sampling the stored input signal with the second sampling frequency, a second calculation and a second angular comparison of two phasors representing the input signal, at two respective instants, as a function of the input signal sampled at the second sampling frequency and of the stored input signal sampled at the second sampling frequency, and estimating the frequency of the input signal.

A method determines the frequency of an alternating input signal includes storing the input signal, sampling the input signal at a first sampling frequency, a first calculation and a first angular comparison of two phasors representing the input signal at two respective instants, as a function of the input signal sampled at the first sampling frequency, estimating the frequency of the input signal, and searching for a modification of frequency of the input signal. When a modification is detected the method includes, determining a second sampling frequency, sampling the stored input signal with the second sampling frequency, a second calculation and a second angular comparison of two phasors representing the input signal, at two respective instants, as a function of the input signal sampled at the second sampling frequency and of the stored input signal sampled at the second sampling frequency, and estimating the frequency of the input signal.

Provided is a detection circuit that has a first inductor connected to two opened input ends and detects an external signal having a waveform with a gradient at each input end. The detection sensor further includes an output circuit that has a second inductor magnetically coupled with the first inductor as a primary side. In the output circuit, a third inductor constituting a delay circuit having one end connected to an intermediate tap of the second inductor is connected. Diodes are respectively connected to terminals of the second inductor in a forward direction. Other terminals of the diodes are connected to another terminal of the third inductor via elements each having an impedance characteristic. The output circuit outputs a detection signal detected at the input ends, from the other terminal(s) of at least one of the diodes.

Provided is a detection circuit that has a first inductor connected to two opened input ends and detects an external signal having a waveform with a gradient at each input end. The detection sensor further includes an output circuit that has a second inductor magnetically coupled with the first inductor as a primary side. In the output circuit, a third inductor constituting a delay circuit having one end connected to an intermediate tap of the second inductor is connected. Diodes are respectively connected to terminals of the second inductor in a forward direction. Other terminals of the diodes are connected to another terminal of the third inductor via elements each having an impedance characteristic. The output circuit outputs a detection signal detected at the input ends, from the other terminal(s) of at least one of the diodes.

A system and method to detect the fundamental frequency of an electric input signal using a feedback control loop including a phase error detector, a loop controller, and a digitally controlled oscillator. The frequency detector may detect the fundamental frequency of an electric input signal and produce an output signal representing the fundamental frequency of the electric input signal. The frequency detector may further include a filter that may be coupled to the frequency detector output signal in order to remove spurious tones or noise from the output signal.

A system and method to detect the fundamental frequency of an electric input signal using a feedback control loop including a phase error detector, a loop controller, and a digitally controlled oscillator. The frequency detector may detect the fundamental frequency of an electric input signal and produce an output signal representing the fundamental frequency of the electric input signal. The frequency detector may further include a filter that may be coupled to the frequency detector output signal in order to remove spurious tones or noise from the output signal.

Apparatus and methods for phase tracking an oscillatory signal are provided. In one arrangement, an input signal is received. First and second reference oscillatory signals are received at the frequency of a target frequency component of the input signal. The first and second reference oscillatory signals are phase shifted relative to each other. Weights of a weighted sum of the first and second reference oscillatory signals are iteratively varied to match the weighted sum to the input signal. The weights of the matched weighted sum are used to provide real time estimates of the phase of the target frequency component of the input signal.

Apparatus and methods for phase tracking an oscillatory signal are provided. In one arrangement, an input signal is received. First and second reference oscillatory signals are received at the frequency of a target frequency component of the input signal. The first and second reference oscillatory signals are phase shifted relative to each other. Weights of a weighted sum of the first and second reference oscillatory signals are iteratively varied to match the weighted sum to the input signal. The weights of the matched weighted sum are used to provide real time estimates of the phase of the target frequency component of the input signal.

The present disclosure provides a measurement application device comprising a display device configured to display measured signals in a diagram, an input device configured to receive a first user-provided input marker, wherein the first user-provided input marker refers to a point in the diagram, and a computing device configured to calculate a difference value for each one of at least two diagram axes based in each case on the position of the first user-provided input marker and a second input marker in the diagram, wherein the computing device is further configured to calculate a result based on the calculated difference values.

The present disclosure provides a measurement application device comprising a display device configured to display measured signals in a diagram, an input device configured to receive a first user-provided input marker, wherein the first user-provided input marker refers to a point in the diagram, and a computing device configured to calculate a difference value for each one of at least two diagram axes based in each case on the position of the first user-provided input marker and a second input marker in the diagram, wherein the computing device is further configured to calculate a result based on the calculated difference values.