A system for analyzing a microwave-frequency signal by imaging is provided, comprising: a solid material at least one optical property of which is modifiable in at least one zone of the material, when the zone is simultaneously in the presence of an optical excitation or electrical excitation and a microwave-frequency signal having at least one frequency coinciding with a resonant frequency of the material,
the material furthermore being such that a value of the resonant frequency varies as a function of the amplitude of a magnetic field, a magnetic field generator configured to generate a magnetic field having, in the interior of a portion of the zone, a spatial amplitude variation in a direction X, the material then having a resonant frequency that is dependent on a position in the direction X, and a detector configured to receive an image of the zone in said direction X.

The invention relates to a device for the spectral analysis of an electromagnetic measurement signal using an optoelectronic mixer, wherein the optoelectronic mixer is designed to generate the electrical superimposition signal by superimposing the electromagnetic measurement signal and a reference signal with at least one known frequency (fo). The device comprises the following features: a signal input for receiving an electrical superimposition signal from the optoelectronic mixer , a low-pass filter, a rectifier, and a read-out unit. The low-pass filter is designed to generate a filtered superimposition signal from the electrical superimposition signal by filtering out frequency portions above an upper cutoff frequency (fG). The rectifier is designed to generate a rectified superimposition signal from the filtered superimposition signal. The read-out unit is designed to determine a match of the known frequency (fo) of the reference signal with the electromagnetic measurement signal based on the rectified overlay signal.

A fiber sheet is densely charged with electric charge and provides an electret fiber sheet that has excellent dust collecting performance. The electret fiber sheet is an electret fiber sheet in which averages of a* values and b* values satisfy all requirements of the following (a) to (c): (a) 10average of (a* values)40; (b) 25average of (b* values)0; and (c) 5average of [(a* values)+(b* values)]40; wherein a* and b* are values measured by a spectrophotometer when a red positive charge toner and a blue negative charge toner are attached.

Systems and methods include a computer-implemented method for determining normalized apparent power. Drilling acoustic signals corresponding to a time domain and generated during drilling of a well. A fast Fourier transformation (FFT) is performed using the drilling acoustic signals to generate FFT data. Normalized FFT data is generated using normalization parameters and a drill string rotation rate record of a drill string used to drill the well. The drill string rotation rate is received during drilling. Normalized apparent power is determined from data points of a predetermined top percentage of the normalized FFT data within a lithological significant frequency range. The normalized apparent power is a measure of the power of the drilling acoustic signals and it is a function of the amplitude and frequency of the normalized FFT data. The lithological significant frequency range is a frequency range within which the drill sounds are more closely related with lithology.

Systems and methods include a computer-implemented method for determining normalized apparent power. Drilling acoustic signals corresponding to a time domain and generated during drilling of a well. A fast Fourier transformation (FFT) is performed using the drilling acoustic signals to generate FFT data. Normalized FFT data is generated using normalization parameters and a drill string rotation rate record of a drill string used to drill the well. The drill string rotation rate is received during drilling. Normalized apparent power is determined from data points of a predetermined top percentage of the normalized FFT data within a lithological significant frequency range. The normalized apparent power is a measure of the power of the drilling acoustic signals and it is a function of the amplitude and frequency of the normalized FFT data. The lithological significant frequency range is a frequency range within which the drill sounds are more closely related with lithology.

The invention relates to a device for detecting an electric arc based on an analog output signal (104) of at least one acoustic wave sensor (102), this device including: an analog-to-digital converter (106) capable of sampling and digitizing the output signal (104) of the sensor (102); a digital processing circuit (110) capable of implementing a frequency domain analysis of the digital output signal (108) of the converter (106) enabling to detect the possible presence of an arc based on its acoustic signature; and an analog circuit (118) for detecting the exceeding of a power threshold by the output signal (104) of the sensor (102), wherein the digital processing circuit (110) is configured to implement the frequency domain analysis only on detection of the exceeding of a threshold by the analog circuit (118).

The invention relates to a device for detecting an electric arc based on an analog output signal (104) of at least one acoustic wave sensor (102), this device including: an analog-to-digital converter (106) capable of sampling and digitizing the output signal (104) of the sensor (102); a digital processing circuit (110) capable of implementing a frequency domain analysis of the digital output signal (108) of the converter (106) enabling to detect the possible presence of an arc based on its acoustic signature; and an analog circuit (118) for detecting the exceeding of a power threshold by the output signal (104) of the sensor (102), wherein the digital processing circuit (110) is configured to implement the frequency domain analysis only on detection of the exceeding of a threshold by the analog circuit (118).

This disclosure relates to optical RF spectrum analysers and methods for analysing an input RF signal. An optical modulator modulates an input RF signal onto a carrier frequency and an optical spectral weight with a spectral weight function modifies the modulated optical signal. The spectral weight defines a frequency relationship between the spectral weight function and the carrier frequency. A frequency control module modifies the frequency relationship between the spectral weight function and the carrier frequency over time. An optical sensor senses the modified optical signal over time and to generates an RF signal over time. A signal recovery module calculates the RF spectrum based on the RF signal over time. Shifting the spectral weight against the carrier frequency over time results in a high spectral resolution even if the spectral weight is relatively broad band. The result is an increased spectral resolution at a reduced price/complexity and increased robustness.

This disclosure relates to optical RF spectrum analysers and methods for analysing an input RF signal. An optical modulator modulates an input RF signal onto a carrier frequency and an optical spectral weight with a spectral weight function modifies the modulated optical signal. The spectral weight defines a frequency relationship between the spectral weight function and the carrier frequency. A frequency control module modifies the frequency relationship between the spectral weight function and the carrier frequency over time. An optical sensor senses the modified optical signal over time and to generates an RF signal over time. A signal recovery module calculates the RF spectrum based on the RF signal over time. Shifting the spectral weight against the carrier frequency over time results in a high spectral resolution even if the spectral weight is relatively broad band. The result is an increased spectral resolution at a reduced price/complexity and increased robustness.

The present invention is directed to a system for measuring noise and velocity of a single object or surface in a soundscape of multiple noise-emitting objects or surfaces. The present invention features a system comprising a heterodyne signal system comprising a signal emitter, a signal receiver, and a signal processing component capable of directing an original signal to the object or surface, accepting a return signal Doppler shifted and mixed with the original signal, and removing the original signal, resulting in an output signal. The system may further comprise an acoustic spectrum analyzer capable of calculating a radiation-factor from the output signal, calculating a mean-squared velocity value by calculating a variance of a spectral shape of the output signal, calculating a noise-sound-power value from the mean-squared velocity value and the radiation-factor, and converting the noise-sound-power value into an acoustic decibel value.