A method includes performing by a processor: receiving a first plurality of power system frequency measurements from a plurality of phasor measurement units (PMUs) in the power system over a first time interval, generating a first plurality of multi-dimensional ellipsoids based on the first plurality of power system frequency measurements, extracting a plurality of first graphic parameter values from the first plurality of multi-dimensional ellipsoids, respectively, performing a regression analysis on the plurality of first graphic parameter values to generate a predictive relationship between the plurality of first graphic parameter values and inertia values of the power system, receiving a second plurality of power system frequency measurements from the plurality of PMUs over a second time interval, generating a second plurality of multi-dimensional ellipsoids based on the second plurality of power system frequency measurements, extracting a plurality of second graphic parameter values from the second plurality of multi-dimensional ellipsoids, respectively, and estimating a current inertia value of the power system based on the plurality of second graphic parameter values by using the predictive relationship between the plurality of first graphic parameter values and the inertia values of the power system.

A method includes performing by a processor: receiving a first plurality of power system frequency measurements from a plurality of phasor measurement units (PMUs) in the power system over a first time interval, generating a first plurality of multi-dimensional ellipsoids based on the first plurality of power system frequency measurements, extracting a plurality of first graphic parameter values from the first plurality of multi-dimensional ellipsoids, respectively, performing a regression analysis on the plurality of first graphic parameter values to generate a predictive relationship between the plurality of first graphic parameter values and inertia values of the power system, receiving a second plurality of power system frequency measurements from the plurality of PMUs over a second time interval, generating a second plurality of multi-dimensional ellipsoids based on the second plurality of power system frequency measurements, extracting a plurality of second graphic parameter values from the second plurality of multi-dimensional ellipsoids, respectively, and estimating a current inertia value of the power system based on the plurality of second graphic parameter values by using the predictive relationship between the plurality of first graphic parameter values and the inertia values of the power system.

A frequency sensor is provided. The frequency sensor may include: a magnetoresistive nano-oscillator including a magnetic heterostructure of at least a magnetic free layer, a magnetic reference layer and a non-magnetic intermediate layer arranged between the magnetic free layer and the magnetic reference layer; a coupling arrangement for coupling an incoming signal to at least one magnetic mode of the magnetic free layer, and a frequency estimator. The frequency estimator may be configured to: perform a plurality of voltage measurements across the magnetoresistive nano-oscillator over time; calculate a time averaged voltage across the magnetoresistive nano-oscillator based on the plurality of voltage measurements; estimate, over a finite range of frequencies, a frequency of the incoming signal based on the calculated time averaged voltage, and output a signal representative of the estimated frequency. A method of estimating a frequency of an incoming signal is also provided.

A frequency sensor is provided. The frequency sensor may include: a magnetoresistive nano-oscillator including a magnetic heterostructure of at least a magnetic free layer, a magnetic reference layer and a non-magnetic intermediate layer arranged between the magnetic free layer and the magnetic reference layer; a coupling arrangement for coupling an incoming signal to at least one magnetic mode of the magnetic free layer, and a frequency estimator. The frequency estimator may be configured to: perform a plurality of voltage measurements across the magnetoresistive nano-oscillator over time; calculate a time averaged voltage across the magnetoresistive nano-oscillator based on the plurality of voltage measurements; estimate, over a finite range of frequencies, a frequency of the incoming signal based on the calculated time averaged voltage, and output a signal representative of the estimated frequency. A method of estimating a frequency of an incoming signal is also provided.

A software-defined radiometer includes dual RF front end channels. One RF front end channel processes the horizontal polarization signals and the other RF front end channel processes the vertical polarization signals. Each RF front end channel includes a power splitter for splitting the polarization signals into a plurality of identical polarization signals, a filter bank of N-bandpass filters that have the same bandwidth but different center frequencies and a multi-input switch. The bandpass filters filter the horizontal and vertical polarization signals and provide a plurality of filtered horizontal and vertical polarization signals. A control circuit issues a control signal to the multi-input switch so as to route a desired one of the plurality of filtered horizontal and vertical polarization signals to a programmable frequency converter. The programmable frequency converter includes a programmable local oscillator that is configured to generate signals having any one of N frequencies and is used to produce intermediate frequency representations of the horizontal and vertical polarization signals. The intermediate frequency representations are converted into digital signals and processed to extract desired information and data.

A software-defined radiometer includes dual RF front end channels. One RF front end channel processes the horizontal polarization signals and the other RF front end channel processes the vertical polarization signals. Each RF front end channel includes a power splitter for splitting the polarization signals into a plurality of identical polarization signals, a filter bank of N-bandpass filters that have the same bandwidth but different center frequencies and a multi-input switch. The bandpass filters filter the horizontal and vertical polarization signals and provide a plurality of filtered horizontal and vertical polarization signals. A control circuit issues a control signal to the multi-input switch so as to route a desired one of the plurality of filtered horizontal and vertical polarization signals to a programmable frequency converter. The programmable frequency converter includes a programmable local oscillator that is configured to generate signals having any one of N frequencies and is used to produce intermediate frequency representations of the horizontal and vertical polarization signals. The intermediate frequency representations are converted into digital signals and processed to extract desired information and data.

In various embodiments, a method for processing a Single-Edge Nibble Transmission Signal is provided. The method includes determining of at least one drop in a signal level of the time-variable Single-Edge Nibble Transmission Signal and at least one next rise in the signal level after the drop in the signal level, determining a time interval between the drop and the next rise in the signal level, and determining a quality of the Single-Edge Nibble Transmission Signal by using the time interval.

In various embodiments, a method for processing a Single-Edge Nibble Transmission Signal is provided. The method includes determining of at least one drop in a signal level of the time-variable Single-Edge Nibble Transmission Signal and at least one next rise in the signal level after the drop in the signal level, determining a time interval between the drop and the next rise in the signal level, and determining a quality of the Single-Edge Nibble Transmission Signal by using the time interval.

An insulation detecting method for the electric machine is provided. The leakage current leakage and the leakage resistance are detected and determined by the output potential waveform resulted from the inversion operation of the first switch and the second switch of the driver. Besides, the signal is amplified through the software or the amplification circuit coupled between the electric machine and the driver to detect the leakage resistance approximately to 5M.

An insulation detecting method for the electric machine is provided. The leakage current leakage and the leakage resistance are detected and determined by the output potential waveform resulted from the inversion operation of the first switch and the second switch of the driver. Besides, the signal is amplified through the software or the amplification circuit coupled between the electric machine and the driver to detect the leakage resistance approximately to 5M.