Spectrum analyzer

About: Spectrum analyzer is a research topic. Over the lifetime, 12217 publications have been published within this topic receiving 101851 citations.

Fully digital spectrum analyzer using time compression and discrete fourier transform techniques

Abstract: A fully digital spectrum analyzer accepting as an input either an analog signal or a series of digital numbers and using time compression and DFT (Discrete Fourier Transform) techniques to provide the spectral component values of the input signal. Novel techniques and means are used in obtaining the power values for selected spectral lines and in averaging these power values. Statistically controlled noise is added to the input of the spectrum analyzer to enhance its resolutin beyond the resolution which would be otherwise available. Advanced and efficient techniques are used for generating and applying trigonometric functions in the course of finding the real and imaginary part of Fourier transforms, and for providing running averages of the power spectra.

Design Issues for a Portable Vocal Analyzer

Abstract: The aim of this paper consists in identifying the main design specifications of a portable analyzer that allows the vocal signal of a person under monitoring to be acquired and stored. Suitable calibration procedures will be also defined for the microphone used in the portable device in order to ensure the traceability of the obtained measurements. The collected data will be used to identify voice disorders, to prevent an improper use of the voice, and to evaluate the vocal effort induced by noisy and/or reverberant environments. The vocal analyzer is based on a contact microphone worn by the person under monitoring and a portable microcontroller-based unit that hosts the conditioning circuitry, analog-to-digital converter, and storing memory. Two alternative sensors are investigated as contact microphones: an accelerometer and an electret condenser microphone. The former is expected to exhibit a negligible sensitivity to airborne effects, and the latter would provide a larger bandwidth, thus allowing parameters related to the vowel quality to be estimated. Particular attention will be paid toward traceability assurance and uncertainty estimation, and a calibration procedure for each of the estimated parameters will be proposed. In this paper, a data-acquisition-board-based setup has been used instead of a portable microcontroller unit in order to easily perform tests that allow the used microphones to be characterized and the calibration procedures for the parameters of interest to be assessed. Experimental results are reported that refer to the estimation of the parameters sound pressure level $(SPL)$ and fundamental frequency $(F_{0})$ .

High impedance fault analyzer in electric power distribution networks

Abstract: A system and method is disclosed for detecting an abnormality in a network for distributing or transmitting electric power at a predetermined fundamental frequency. The system produces a signal representing the fundamental frequency and another signal representing a harmonic current occurring in the network. The phasor relation between the fundamental voltage and harmonic current representing signal are compared. The system produces a signal indicating the occurrence of a high impedance fault in response to a predetermined change in the compared phasor relationship. Embodiments are disclosed utilizing expression of signals within the network in polar coordinates, as well as embodiments utilizing signals expressed in rectangular coordinates. Such embodiments include circuitry for detecting zero crossing phenomena, as well as circuitry for producing representation of signal products.

Spectral measuring apparatus and automatic analyzer

Abstract: In order to make a Raman spectral measuring apparatus effective for measurement of a vital sample and attain miniaturization and weight reduction, a near infrared laser diode is employed as a light source (22), and a spectroscope (52) for receiving Raman scattered light from the sample is formed by a polychrometer comprising a concave diffraction grating (54) and a multichannel photodiode array (56). The Raman scattered light incident through an inlet slit (50) is separated into its spectral components by the diffraction grating (54), and its spectra are simultaneously detected by the photodiode array (56) over a prescribed wavelength region.

Wavelength and line width measurement of optical sources with femtometre resolution

Abstract: A new and very simple method for the wavelength and line width measurement of optical sources with a resolution in the femtometre range is presented. Our method is based on the amplification of a backscattered wave by a pump wave due to Brillouin scattering. It requires neither a fast photodiode nor a spectrum analyser of any kind.