Fractional Fourier Transform (FrFT)-based spectrum analyzers and spectrum analysis techniques are disclosed. Rather than using the standard Fast Fourier Transform (FFT), the FrFT may be used to view the signal content contained in a particular bandwidth. Usage of the FrFT in place of the frequency or time domain allows viewing of the signal in different dimensions, where spectral features of interest, or signal content, may appear where they were not visible in these domains before. This may allow signals to be identified and viewed in any domain within the continuous time-frequency plane, and may significantly enhance the ability to detect and extract signals that were previously hidden under interference and/or noise, provide or enhance the ability to extract signals from a congested environment, and enable operation in a signal-dense environment.

Fractional Fourier Transform (FrFT)-based spectrum analyzers and spectrum analysis techniques are disclosed. Rather than using the standard Fast Fourier Transform (FFT), the FrFT may be used to view the signal content contained in a particular bandwidth. Usage of the FrFT in place of the frequency or time domain allows viewing of the signal in different dimensions, where spectral features of interest, or signal content, may appear where they were not visible in these domains before. This may allow signals to be identified and viewed in any domain within the continuous time-frequency plane, and may significantly enhance the ability to detect and extract signals that were previously hidden under interference and/or noise, provide or enhance the ability to extract signals from a congested environment, and enable operation in a signal-dense environment.

A harmonic information extraction circuit is provided. The harmonic information extraction circuit includes a sampling module, an amplitude regulation module and an envelope extraction module. The sampling module is electrically connected to signal terminals of an electronic equipment to acquire a first sampling signal, and generates a first output signal. The first sampling signal includes first and second target band signals and a non-target band signal. The amplitude regulation module receives the first output signal, adjust at least one of an amplitude of the first target band signal and an amplitude of the second target band signal for ensuring that a ratio of the amplitude of the first target band signal to the amplitude of the second target band signal falls within a preset range, and generates a second output signal. The envelope extraction module receives the second output signal and extracts an envelope of the second output signal.

A harmonic information extraction circuit is provided. The harmonic information extraction circuit includes a sampling module, an amplitude regulation module and an envelope extraction module. The sampling module is electrically connected to signal terminals of an electronic equipment to acquire a first sampling signal, and generates a first output signal. The first sampling signal includes first and second target band signals and a non-target band signal. The amplitude regulation module receives the first output signal, adjust at least one of an amplitude of the first target band signal and an amplitude of the second target band signal for ensuring that a ratio of the amplitude of the first target band signal to the amplitude of the second target band signal falls within a preset range, and generates a second output signal. The envelope extraction module receives the second output signal and extracts an envelope of the second output signal.

A wideband device for the spectral analysis of a signal of interest includes a source designed to generate the signal of interest; an optical splitter element designed to spatially split the signal of interest into a first signal and a second signal; a first frequency-shifting optical cavity comprising a first frequency shifter designed to shift the optical frequency of the first signal by a first frequency f.sub.1 per round trip in the first cavity, the first cavity having a first trip time .sub.1; a second frequency-shifting optical cavity comprising a second frequency shifter designed to shift the optical frequency of the second signal by a second frequency f.sub.2 per round trip in the second cavity, the second cavity having a second trip time .sub.2; the first and the second optical cavity being designed such that a maximum number of round trips of the signal in the first and the second cavity is equal to predetermined N; a detector designed to coherently detect the first signal transmitted by the first cavity and the second signal transmitted by the second cavity and generate a photocurrent proportional to a luminous intensity detected by the detector, an analog low-pass filter designed to filter frequencies of the photocurrent that are lower than min (f.sub.1/2, f.sub.2/2) a processor configured to compute a square modulus of the photocurrent filtered by the low-pass filter, from which a temporal representation of frequency information of the signal of interest is determined.

A wideband device for the spectral analysis of a signal of interest includes a source designed to generate the signal of interest; an optical splitter element designed to spatially split the signal of interest into a first signal and a second signal; a first frequency-shifting optical cavity comprising a first frequency shifter designed to shift the optical frequency of the first signal by a first frequency f.sub.1 per round trip in the first cavity, the first cavity having a first trip time .sub.1; a second frequency-shifting optical cavity comprising a second frequency shifter designed to shift the optical frequency of the second signal by a second frequency f.sub.2 per round trip in the second cavity, the second cavity having a second trip time .sub.2; the first and the second optical cavity being designed such that a maximum number of round trips of the signal in the first and the second cavity is equal to predetermined N; a detector designed to coherently detect the first signal transmitted by the first cavity and the second signal transmitted by the second cavity and generate a photocurrent proportional to a luminous intensity detected by the detector, an analog low-pass filter designed to filter frequencies of the photocurrent that are lower than min (f.sub.1/2, f.sub.2/2) a processor configured to compute a square modulus of the photocurrent filtered by the low-pass filter, from which a temporal representation of frequency information of the signal of interest is determined.

In an embodiment, an electronic circuit includes: one or more input terminals configured to receive measurement data; and a controller configured to: determine a first harmonic current based on a first current flowing through a first circuit coupled to a line node, where the measurement data includes first current data indicative of the first current, determine a filter harmonic current based on a filter current flowing through an AC filter coupled to the line node, where the measurement data includes filter current data indicative of the filter current, and generate a first flag indicative of failure, degradation or malfunction of a first capacitor or capacitor bank based on the first harmonic current and the filter harmonic current, where the AC filter includes the first capacitor or capacitor bank.

In an embodiment, an electronic circuit includes: one or more input terminals configured to receive measurement data; and a controller configured to: determine a first harmonic current based on a first current flowing through a first circuit coupled to a line node, where the measurement data includes first current data indicative of the first current, determine a filter harmonic current based on a filter current flowing through an AC filter coupled to the line node, where the measurement data includes filter current data indicative of the filter current, and generate a first flag indicative of failure, degradation or malfunction of a first capacitor or capacitor bank based on the first harmonic current and the filter harmonic current, where the AC filter includes the first capacitor or capacitor bank.

Disclosed implementations determine transient distortions, amplitude distortions, and/or periodic distortions present in a voltage signal measured from an electrical circuit at a location and use those distortions to determine a device type of a device operating on the electrical circuit at the location. In some examples, the voltage signal may be filtered into a plurality of sub-bands and one or more two-dimensional representations generated based on transient distortions, amplitude distortions, and/or periodic distortions determined in each sub-band. The one or more 2D representations may be provided to a deep neural network to determine a device type that generated the distortions on the electrical circuit.

Disclosed implementations determine transient distortions, amplitude distortions, and/or periodic distortions present in a voltage signal measured from an electrical circuit at a location and use those distortions to determine a device type of a device operating on the electrical circuit at the location. In some examples, the voltage signal may be filtered into a plurality of sub-bands and one or more two-dimensional representations generated based on transient distortions, amplitude distortions, and/or periodic distortions determined in each sub-band. The one or more 2D representations may be provided to a deep neural network to determine a device type that generated the distortions on the electrical circuit.