A spectrum analyzer having a memory function to adopt a digital-data-based frequency sweep scheme while achieving performance comparable to performance of a high-speed FFT spectrum analyzer, and a method of controlling the spectrum analyzer, in which the spectrum analyzer includes: an ADC for converting a BWP signal, which is at least one analog unit frequency band signal, into a digital data sample at a predetermined sample rate according to a span set by a user; a digital sweep part for sweeping the data sample passed through the ADC while digitally decimating the data sample through a decimation processing block having a two-stage cascaded structure, and processing the swept data sample to increase a frequency sweep speed; and a control unit for controlling the digital sweep part according to various items input, set, and selected by the user to perform spectrum analysis and output a spectrum analysis result.

Systems, apparatuses, methods and computer processes to separate and select frequency components of a signal in real time without phase delay by predicting or forecasting future values of the signal and using that forecast and past measurements in a noncausal zero-phase filtering algorithm are provided. The method of separating and selecting frequency components of a signal in real time without phase delay using a zero-phase filter, comprises obtaining past measurements of the signal; obtaining predicted values of the signal; and using the predicted values of the signal and the past measurements of the signal as components of an input signal in a noncausal zero-phase filtering algorithm for a zero-phase filter, the zero-phase filter producing an output signal.

Systems, apparatuses, methods and computer processes to separate and select frequency components of a signal in real time without phase delay by predicting or forecasting future values of the signal and using that forecast and past measurements in a noncausal zero-phase filtering algorithm are provided. The method of separating and selecting frequency components of a signal in real time without phase delay using a zero-phase filter, comprises obtaining past measurements of the signal; obtaining predicted values of the signal; and using the predicted values of the signal and the past measurements of the signal as components of an input signal in a noncausal zero-phase filtering algorithm for a zero-phase filter, the zero-phase filter producing an output signal.

Systems and methods herein provide for sinusoidal signal distortion monitoring and visualization via a Circular Trajectory Approach (CTA). In one embodiment, a system includes a differentiator operable to differentiate an input signal from a sinusoidal signal at substantially a same fundamental frequency of the input signal. The input signal comprising a sinusoidal waveform having distortions. The system also includes a processor operable to calculate a distance index from the input signal to a derivative of the input signal to reveal distortions in the input signal, and a display operable to display the distortions in the input signal.

Systems and methods herein provide for sinusoidal signal distortion monitoring and visualization via a Circular Trajectory Approach (CTA). In one embodiment, a system includes a differentiator operable to differentiate an input signal from a sinusoidal signal at substantially a same fundamental frequency of the input signal. The input signal comprising a sinusoidal waveform having distortions. The system also includes a processor operable to calculate a distance index from the input signal to a derivative of the input signal to reveal distortions in the input signal, and a display operable to display the distortions in the input signal.

A method for partial discharge recognition in high voltage applications and a high voltage unit using the method, includes the steps of detecting a signal, transforming the signal from time to frequency domain, cutting frequencies above a defined threshold, and retransform the truncated signal from frequency to time domain. The information content of detected and truncated signals is determined and compared.

A method for partial discharge recognition in high voltage applications and a high voltage unit using the method, includes the steps of detecting a signal, transforming the signal from time to frequency domain, cutting frequencies above a defined threshold, and retransform the truncated signal from frequency to time domain. The information content of detected and truncated signals is determined and compared.

A method of generating an analytical signal for signal analysis. The method includes obtaining a digital signal, sectioning the digital signal into a series of overlapping windows in time domain, generating a plurality of energy pulses by evaluating a function that describes energy information within each window or set of windows, and generating a time-dependent analytical signal by generating an oscillating signal by multiplying each of the plurality of energy pulses by an oscillating function; and integrating the oscillating function across a band pass frequency filter.

A method of generating an analytical signal for signal analysis. The method includes obtaining a digital signal, sectioning the digital signal into a series of overlapping windows in time domain, generating a plurality of energy pulses by evaluating a function that describes energy information within each window or set of windows, and generating a time-dependent analytical signal by generating an oscillating signal by multiplying each of the plurality of energy pulses by an oscillating function; and integrating the oscillating function across a band pass frequency filter.

A method for separating spectrums of an input signal having a first spectrum and a second spectrum by mixing the input signal at a first mixer with a first frequency to obtain a first mixed signal; mixing the input signal at a second mixer with second frequency to obtain a second mixed signal; displacing the first mixed signal and/or the second mixed signal up and down by the difference of the first and second frequency obtaining at least one lower auxiliary signal and at least one upper auxiliary signal, respectively; and extracting the first spectrum and/or the second spectrum using the lower auxiliary signal and/or the upper auxiliary signal as well as the first mixed signal and/or the second mixed signal. Further, measurement devices for separating spectrums are shown.