Topic
Spectrum analyzer
About: Spectrum analyzer is a research topic. Over the lifetime, 12217 publications have been published within this topic receiving 101851 citations.
Papers published on a yearly basis
Papers
More filters
Patent•
01 May 2005
TL;DR: In this paper, an apparatus for QRS waveform quantification, comprising an input unit (310) for receiving one or more high frequency (HF) range QRS complexes from one or several ECG leads, a primary analyzer (320), for calculating a primary index from the high frequency range QRs complex, and a secondary analyzer connected after the primary analyzers, for deriving a secondary index from a primary signal index, thereby to provide a quantification of QRS complex.
Abstract: An apparatus (300) for QRS waveform quantifying, comprising: an input unit (310), for receiving one or more high frequency (HF) range QRS complexes from one or more ECG leads, a primary analyzer (320), for calculating a primary index from the high frequency (HF) range QRS complex, and a secondary analyzer (330), connected after the primary analyzer, for deriving a secondary index from the primary index, thereby to provide a quantification of QRS complexes.
24 citations
Patent•
14 Jun 1999
TL;DR: In this article, a spectrum analyzer can be used to produce a first two-dimensional array of time varying spectral analysis image input signals, a reference image generator for producing a second two-dimensions array of spectral analysis reference signals, and a timeintegrative correlator, which can be non-coherent or coherent, or correlating the two groups of image representitive signals to determine the degree of matching between an input image and a library reference image.
Abstract: A spectrum analyzer for producing a first two-dimensional array of time varying spectral analysis image input signals, a reference image generator for producing a second two-dimensional array of spectral analysis image reference signals, and a time-integrative correlator, which can be non-coherent or coherent, or correlating the two groups of image representitive signals to determine the degree of matching between an input image and a library reference image. The spectrum analyzer can include an interferometer, a tunable optical filter, or a time-wavelength-multiplexing holographic lens for viewing the input image. A monolithic non-holographic version provides a rugged, compact and portable image analyzer for examining many types of images.
24 citations
TL;DR: A vector Brillouin optical time-domain analyzer that has a high immunity level to noise, and it features a phase spectrogram capability, well suited for complex situations involving several acoustic resonances, such as high-order longitudinal modes.
Abstract: Thanks to a double-frequency phase modulation scheme, we report a vector Brillouin optical time-domain analyzer (BOTDA). This BOTDA has a high immunity level to noise, and it features a phase spectrogram capability. It is well suited for complex situations involving several acoustic resonances, such as high-order longitudinal modes. It has notably been used to characterize a dispersion-shifted fiber, allowing us to report spectrograms with multiple acoustic resonances. A very high 57dB dynamic range is also reported for 100-ns-long pulses simultaneously with a 16cm numerical resolution.
24 citations
Patent•
16 Sep 1974
TL;DR: In this article, an apparatus for determining the composition of a gas by measuring the acoustic impedence and absorption of the gas at two distinct frequencies is presented, where the velocity variations due to the presence of a gaseous gas in a fixed length column are measured by comparing the phase of the voltage applied to a sending transducer to the phase in a receiving transducers, since the distance between the transducers is fixed, the phase variation is indicative of the velocity of sound at any particular frequency.
Abstract: An apparatus for determining the composition of a gas by measuring the acoustic impedence and absorption of a gas at two distinct frequencies. The velocity variations due to the presence of a gas in a fixed length column are measured by comparing the phase of the voltage applied to a sending transducer to the phase of the voltage in a receiving transducer. Since the distance between the transducers is fixed, the phase variation is indicative of the velocity of the sound at any particular frequency. The output voltage obtained from a phase comparator is proportional to the phase difference and since the relationship between the concentration of the gas and the output voltage is known, the concentration of the gas is easily ascertained. The influence of temperature changes in the column are eliminated by summing the phase differences measured at the two distinct frequencies. In addition, by a judicious choice of frequencies, the amount of water vapor present in a particular gas may be compensated for.
24 citations
Patent•
26 Mar 1982
TL;DR: In this article, the authors used a frequency analyzer with the possible intermediary of a multi-track tape recorder, the analyzer output being displayed by a printer, preferably of ink-jet form.
Abstract: Attempts have been made to facilitate orthopedic diagnostic procedures by microphonic detection of emissions from a moving joint, with analysis of such emissions to establish correlation with pathological conditions, but these attempts have failed. Success in such a procedure is now found to require detection of emissions extending into the subsonic frequency range. Preferably a piezoelectric accelerometer detector (10) is used in direct contact with the skin. A plurality of detectors can be used around a joint with comparative analysis to localize a condition. Analysis suitably involves a frequency analyzer (14) with the possible intermediary of a multi-track tape recorder (12), the analyzer output being displayed by a printer (15) preferably of ink-jet form. One useful correlating emission characteristic is peak frequency for early diagnosis for congenital dislocation of the hip in an infant.
24 citations