A test and measurement device has an input port configured to receive a signal from a device under test, the signal having a symbol rate, one or more analog-to-digital converters to convert the signal to waveform samples at a sampling rate, and one or more processors configured to execute code that, when aliasing is present in the waveform samples, causes the one or more processors to: up-sample the waveform samples to produce up-sampled samples; use the up-sampled samples to produce a real-time waveform; perform clock recovery on the real-time waveform to produce a recovered clock; and resample the waveform samples using the recovered clock to produce a non-aliased waveform. A method of acquiring a waveform in a test and measurement device includes receiving a signal from a device under test, the signal having a symbol rate, converting the signal to waveform samples at a sampling rate of the test and measurement device, when aliasing is present in the waveform samples, up-sampling the waveform samples to produce up-sampled samples, using the up-sampled samples to produce a real-time waveform, performing clock recovery on the real-time waveform to produce a recovered clock, and resampling the waveform samples using the recovered clock to produce a non-aliased waveform.

A test and measurement device has an input port configured to receive a signal from a device under test, the signal having a symbol rate, one or more analog-to-digital converters to convert the signal to waveform samples at a sampling rate, and one or more processors configured to execute code that, when aliasing is present in the waveform samples, causes the one or more processors to: up-sample the waveform samples to produce up-sampled samples; use the up-sampled samples to produce a real-time waveform; perform clock recovery on the real-time waveform to produce a recovered clock; and resample the waveform samples using the recovered clock to produce a non-aliased waveform. A method of acquiring a waveform in a test and measurement device includes receiving a signal from a device under test, the signal having a symbol rate, converting the signal to waveform samples at a sampling rate of the test and measurement device, when aliasing is present in the waveform samples, up-sampling the waveform samples to produce up-sampled samples, using the up-sampled samples to produce a real-time waveform, performing clock recovery on the real-time waveform to produce a recovered clock, and resampling the waveform samples using the recovered clock to produce a non-aliased waveform.

A voltage measurement device includes a probe module movably arranged around an alternating-current transmission line, and a measurement unit. A metal electrode is arranged on a surface of the probe module facing toward the alternating-current transmission line, electrically coupled with the alternating-current transmission line to form a coupling capacitor, and then forms an electrical circuit with an inductor element, a resistor element, and a reference signal source in the measurement unit. A processor controls the reference signal source to input reference voltage signals at different frequencies to the electrical circuit, determines a resonant frequency of the electrical circuit according to currents of the electrical circuit under the reference voltage signals at different frequencies, and determines a voltage of the alternating-current transmission line according to a first current component amplitude and the resonant frequency of the electrical circuit. A voltage measurement method and a storage medium are also disclosed.

A voltage measurement device includes a probe module movably arranged around an alternating-current transmission line, and a measurement unit. A metal electrode is arranged on a surface of the probe module facing toward the alternating-current transmission line, electrically coupled with the alternating-current transmission line to form a coupling capacitor, and then forms an electrical circuit with an inductor element, a resistor element, and a reference signal source in the measurement unit. A processor controls the reference signal source to input reference voltage signals at different frequencies to the electrical circuit, determines a resonant frequency of the electrical circuit according to currents of the electrical circuit under the reference voltage signals at different frequencies, and determines a voltage of the alternating-current transmission line according to a first current component amplitude and the resonant frequency of the electrical circuit. A voltage measurement method and a storage medium are also disclosed.

Method and system for evaluating an input voltage of a power supply or a switched-mode power supply, wherein the input voltage has a constant polarity, where a digitized input voltage is supplied as the input signal to a filter which is filtered such that an output signal from the filter lags the input signal of the filter at the input of the filter, where the input signal and the output signal of the filter are compared, where comparison results are evaluated during an evaluation period until, following a first change in state of a comparison result, a further change in state of the comparison result is identified, and where a respective evaluation period is then terminated and subsequently, a period duration and/or a frequency of an AC voltage component of the input voltage are determined using the present count value of a counter.

A diagnostic system includes a fan control circuit coupled to an electric fan and a microcontroller, and a sense line coupled to the fan control circuit and the microcontroller. The fan control circuit outputs a fan command sense signal at a duty cycle through the sense line to the microcontroller. A tachometer generates a tachometer signal at a frequency indicative of the rotational speed of the electric fan. A fan tachometer circuit receives the tachometer signal and outputs the tachometer sense signal at a frequency to the microcontroller in response to the tachometer signal. The microcontroller sets a second diagnostic flag to an error value indicating that the sense line has impaired operation if the frequency of the tachometer sense signal is within a desired frequency range, and a first diagnostic flag is equal to a first error value.

A diagnostic system includes a fan control circuit coupled to an electric fan and a microcontroller, and a sense line coupled to the fan control circuit and the microcontroller. The fan control circuit outputs a fan command sense signal at a duty cycle through the sense line to the microcontroller. A tachometer generates a tachometer signal at a frequency indicative of the rotational speed of the electric fan. A fan tachometer circuit receives the tachometer signal and outputs the tachometer sense signal at a frequency to the microcontroller in response to the tachometer signal. The microcontroller sets a second diagnostic flag to an error value indicating that the sense line has impaired operation if the frequency of the tachometer sense signal is within a desired frequency range, and a first diagnostic flag is equal to a first error value.

A compensator circuit for a PWM active rectifier includes a look up table containing compensating voltage values for given values of input phase current and input voltage frequency, and a low pass filter arranged to filter the input phase current to the rectifier based on a filter bandwidth determined according to the input voltage frequency. The compensator circuit arranged to receive measured input current and voltage frequency values and to output corresponding compensation voltage values from the look up table, the compensation voltages to be provided, in use, to the rectifier to adjust the switching pattern of the rectifier.

A compensator circuit for a PWM active rectifier includes a look up table containing compensating voltage values for given values of input phase current and input voltage frequency, and a low pass filter arranged to filter the input phase current to the rectifier based on a filter bandwidth determined according to the input voltage frequency. The compensator circuit arranged to receive measured input current and voltage frequency values and to output corresponding compensation voltage values from the look up table, the compensation voltages to be provided, in use, to the rectifier to adjust the switching pattern of the rectifier.

A method of processing power signals is provided. The method includes: receiving an analog poly-phase signal associated with power delivered using alternating current (AC); converting the analog poly-phase signal to a digital poly-phase signal sampled at a first sampling rate; detecting a fundamental frequency of the analog poly-phase signal; determining a second sampling rate, wherein the second sampling rate is based on and tracks the fundamental frequency; resampling the digital poly-phase signal at the second sampling rate; for each cycle of the resampled digital poly-phase signal: transforming the resampled digital poly-phase digital signal to a frequency-domain signal; calculating a phase angle of the reference voltage component; adjusting the resampled digital poly-phase signal by compensating the calculated phase angle; and transforming the adjusted resampled digital poly-phase signal to an updated frequency-domain signal using FFT; and calculating one or more measurements based on the updated frequency-domain signal.