Various examples of methods and systems are disclosed for correction of phase and amplitude errors that occur in transmission lines connecting transmitter/receiver devices to measurement fixtures. In one example, a method is described that includes using time domain processing to determine a phase shift from the measurement fixture that can occur between calibration measurements and measurements of the specimen under test. In another example, a method is described that includes frequency-domain processing of the signals to obtain both phase and amplitude corrections. Including these phase and amplitude corrections in the calibration procedure can reduce or minimize the errors induced in the measurements when the transmission line(s) experience either temperature changes or physical deflections, among other things.

A test and measurement instrument, such as an oscilloscope, having a Nyquist frequency lower than an analog bandwidth, the test and measurement instrument having an input configured to receive a signal under test having a repeating pattern, a single analog-to-digital converter configured to receive the signal under test and sample the signal under test over a plurality of repeating patterns at a sample rate, and one or more processors configured to determine a frequency of the signal under test and reconstruct the signal under test based on the determined frequency of the signal, the pattern length of the signal under test, and/or the sample rate without a trigger.

A test and measurement instrument, such as an oscilloscope, having a Nyquist frequency lower than an analog bandwidth, the test and measurement instrument having an input configured to receive a signal under test having a repeating pattern, a single analog-to-digital converter configured to receive the signal under test and sample the signal under test over a plurality of repeating patterns at a sample rate, and one or more processors configured to determine a frequency of the signal under test and reconstruct the signal under test based on the determined frequency of the signal, the pattern length of the signal under test, and/or the sample rate without a trigger.

A method and device for increasing an accuracy of a phase measurement, wherein the method includes: receiving a measurement signal; performing a frequency-domain transformation to the measurement signal to obtain a frequency-domain measurement sequence; determining phases that correspond to frequency-domain measurement signals, and determining a phase difference between the frequency-domain measurement signals that correspond to two neighboring specified frequency points; according to the phases, the phase difference and a window function, performing a sliding-window-type phase fitting to the frequency-domain measurement sequence, to obtain phase-fitting data that correspond to sliding windows; and according to the phase-fitting data of the sliding windows, determining phase-calibration data that correspond to the sliding windows, and, by using the phase-calibration data of the sliding windows, forming phase-calibration data within a specified frequency band. The method reduces an error of fitting, and increases an accuracy of a phase calibration.

A method and device for increasing an accuracy of a phase measurement, wherein the method includes: receiving a measurement signal; performing a frequency-domain transformation to the measurement signal to obtain a frequency-domain measurement sequence; determining phases that correspond to frequency-domain measurement signals, and determining a phase difference between the frequency-domain measurement signals that correspond to two neighboring specified frequency points; according to the phases, the phase difference and a window function, performing a sliding-window-type phase fitting to the frequency-domain measurement sequence, to obtain phase-fitting data that correspond to sliding windows; and according to the phase-fitting data of the sliding windows, determining phase-calibration data that correspond to the sliding windows, and, by using the phase-calibration data of the sliding windows, forming phase-calibration data within a specified frequency band. The method reduces an error of fitting, and increases an accuracy of a phase calibration.

A method for providing a frequency of an electrical quantity in an electrical power system comprises obtaining (30), with respect to a first time, a first discrete Fourier transform, DFT, phasor of an electrical quantity in the electrical power system, estimating (32) a second DFT phasor at a time interval before the first time, where the time interval depends on an approximated frequency, and determining (34) the frequency at the first time based on the first and the second DFT phasor.

Disclosed are exemplary embodiments for monitoring for and/or detecting freeze-up and/or paddle wear conditions within dispensers and mixers associated with soft frozen desserts (broadly, edibles or edible products) and crushed ice drinks (broadly, drinkables or potable products).

Disclosed are exemplary embodiments for monitoring for and/or detecting freeze-up and/or paddle wear conditions within dispensers and mixers associated with soft frozen desserts (broadly, edibles or edible products) and crushed ice drinks (broadly, drinkables or potable products).

A fault detection method and device for elevator power equipment and an elevator system. The method includes acquiring running speed data of an actuator in the elevator power equipment, and using the corresponding running speed data when the elevator is at a first speed and within a preset duration as target data; obtaining time-domain signal data of acceleration by calculation according to the target data, obtaining frequency-domain signal data of acceleration by conversion according to the time-domain signal data; comparing peak frequencies that form waveform peaks in the frequency-domain signal data with characteristic frequencies of the elevator power equipment, and determining the elevator power equipment to be faulty when at least one first frequency is detected in the peak frequencies, wherein the first frequency matches one of the characteristic frequencies and the amplitude thereof exceeds a preset threshold.

A fault detection method and device for elevator power equipment and an elevator system. The method includes acquiring running speed data of an actuator in the elevator power equipment, and using the corresponding running speed data when the elevator is at a first speed and within a preset duration as target data; obtaining time-domain signal data of acceleration by calculation according to the target data, obtaining frequency-domain signal data of acceleration by conversion according to the time-domain signal data; comparing peak frequencies that form waveform peaks in the frequency-domain signal data with characteristic frequencies of the elevator power equipment, and determining the elevator power equipment to be faulty when at least one first frequency is detected in the peak frequencies, wherein the first frequency matches one of the characteristic frequencies and the amplitude thereof exceeds a preset threshold.