Spectrum analyzer

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

A solid-state arteriovenous oxygen difference analyzer for flowing whole blood

Abstract: This communication describes a spectrophotometric device which determines the arteriovenous oxygen difference (a-v O2) on whole blood flowing through optical cuvettes. The instrument consists entirely of commercially available solid-state components, including the light sources, light-emitting diodes. When calibrated against conventional determinations of blood oxygen content, the output of the a-v O2 analyzer was shown to be highly linear and to be independent of total hemoglobin concentration. The electronic circuit, the theory of the measurement, and sources of error are described in detail.

Microphone array signal enhancement

Abstract: A system and method facilitating signal enhancement utilizing an adaptive filter is provided. The invention includes an adaptive filter that filters an input based upon a plurality of adaptive coefficients and modifies the adaptive coefficients based on a feedback output. A feedback component provides the feedback output based, at least in part, upon a non-linear function of the acoustic reverberation reduced output. Optionally, the system can further include a linear prediction (LP) analyzer and/or a LP synthesis filter. The system can enhance signal(s), for example, to improve the quality of speech that is acquired by a microphone by reducing reverberation. The system utilizes, at least in part, the principle that certain characteristics of reverberated speech are measurably different from corresponding characteristics of clean speech. The system can employ a filter technology (e.g., reverberation reducing) based on a non-linear function, for example, the kurtosis metric.

Improving the performance of high-resolution X-ray spectrometers with position-sensitive pixel detectors.

Abstract: A dispersion-compensation method to remove the cube-size effect from the resolution function of diced analyzer crystals using a position-sensitive two-dimensional pixel detector is presented. For demonstration, a resolution of 23 meV was achieved with a spectrometer based on a 1 m Rowland circle and a diced Si(555) analyzer crystal in a near-backscattering geometry, with a Bragg angle of 88.5°. In this geometry the spectrometer equipped with a traditional position-insensitive detector provides a resolution of 190 meV. The dispersion-compensation method thus allows a substantial increase in the resolving power without any loss of signal intensity.

Nine-crystal multianalyzer stage for high-resolution powder diffraction between 6 keV and 40 keV

Abstract: For powder diffraction, high resolution can be best achieved using the parallel beam geometry with a monochromator/analyzer combination. However experiments are long and a way to reduce this time without compromising resolution is to use several analyzer/ detector combinations mounted on a single (theta) a/2(theta) a goniometer. We have developed such a solution for the 'Powder Diffraction' BM16-ESRF beam line. This device comprises nine analyzer/detectors, with a fixed prealigned offset of two degrees between adjacent analyzer crystals, and can be used in the whole energy range of the powder diffraction instrument (from 6 to 40 keV). The only required adjustment is the classical (theta) a/2(theta) a rotation of the supporting goniometer when the wavelength is changed. Moreover, the detector array can be used in the Debye Scherrer geometry without dismounting the multi-analyzer stage, only by positioning the goniometer at an ad-hoc (theta) a/2(theta) a angle, and inserting slits in front of the detectors. This multi-analyzer system is mainly dedicated to high resolution experiments and a peak width (FWHM) of 0.006 degrees in 2(Theta) has been achieved with a Si(111) monochromator on the BM16 ESRF beam line. Since the prealigned offset is small (2 degrees), the measuring time can be considerably reduced even for scans of small angular ranges, for high energy experiments or for high resolution in-situ studies. This set-up has also been used for anomalous diffraction studies and experiments on amorphous compounds, where it provides efficient elimination of fluorescence scattering and background from ancillary equipment. This system is in operation on the ESRF powder diffraction BM16 beam line since 1996 and has been extensively used for more than 90% of the beam time.

Phase detection of surface plasmon resonance using rotating analyzer method

Abstract: This paper demonstrates the application of the rotating analyzer method to the phase measurement of surface plasmon resonance (SPR) in the Kretschmann configuration. While a few groups have adopted the heterodyne detection method for the phase measurement of SPR, few reports has been appeared on the phase detection based on the rotating analyzer method. We show that the rotating analyzer method have an index resolution of the order of 1 0 − 7 , which is almost compatible with that of the heterodyne detection and is about two orders of magnitude better than the conventional SPR method based on the resonance angular detection. In addition, the rotating analyzer method has advantages that the optical setup is simple and that it is applicable to the spectroscopic measurements.