Spectrum analyzer

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

Single-scan interferometric component analyzer

Abstract: We describe a novel interferometric method for characterizing optical components in the 1.5-/spl mu/m communications band. A complete polarization-resolved characterization of optical components is achieved with just one scan of a tunable laser. Measurements of three devices are presented, including a molecular gas cell, an arrayed waveguide grating, and a tunable dispersion compensator. A dynamic range of greater than 80 dB is demonstrated.

Wide-band electrooptic guided-wave analog-to-digital converters

Abstract: Progress in the development of high-speed electrooptic A/D converters is reviewed. A/D converters of this type have been operated at 1 gigasample/second (GS/s) in 2- and 4-bit structures for 500-MHz analog bandwidth. The converter consists of an array of LiNbO 3 guided-wave interferometric modulators that function as an analog amplitude analyzer, pulsed lasers for optical sampling, and high-speed monolithic comparators/demultiplexers to generate the digital levels and slow the data to ECL-compatible rates. The operational principles of the converter are summarized and a performance analysis presented. The analysis indicates that with currently attainable components, conversion in the 4- to 6-bit range at rates from 1 to 3 GS/s is feasible. Experimental results for several converters are summarized, including a description of beatfrequency tests for analog signals with frequency content up to 500 MHz that indicate the analog bandwidth capabilities of this device. The electrooptical technology is compared to competing high-speed A/D technologies in Si, GaAs, and superconducting materials and the relative merits analyzed. It is found that the electrooptic approach eliminates some of the fundamental and severe problems of conventional converters (e.g., sampling pickup and large numbers of comparators). Finally, application of this converter to wide-band signal-processing problems is described. It is noted that there are numerous applications where a moderate number of bits at a high (gigahertz) sampling rate is attractive.

Chemical analyzer with automatic calibration

Abstract: Improved apparatus for automatically calibrating and verifying the calibration of a chemical analyzer of the type which determines the concentration of a component in chemical or biological samples, e.g. concentration of glucose in blood or urine, wherein a sample changer sequentially advances samples into position for analysis. Calibration of the analyzer is performed by measuring a calibration standard of known concentration and generating a conversion factor therefor which converts the measured value of the standard to the known value thereof. Means is provided for storing conversion factors and proper calibration of the analyzer is verified by comparing successive conversion factors. If the compared conversion factors differ by more than a predetermined amount, the sample changer is halted and the calibration standard is remeasured. Measurement of the calibration standard is repeated until either two successive calibration factors are generated which differ by less than the predetermined amount, or until a predetermined number of unsuccessful measurements are made at which time the analyzer is stopped.

Real-time eeg spectral analyzer

Abstract: An electroencephelograph (EEG) signal analysis system automatically determines and displays, on a real-time basis, the frequency content of spontaneous EEG signals from the brain. The analog EEG signals from a plurality of channels are sampled and converted to digitized EEG waveforms during a continuing sequence of epochs of predetermined time duration. The digitized EEG waveform for each epoch and channel is transformed from the time domain to the frequency domain to produce a frequency spectrum representing amplitude of the EEG signal as a function of frequency. The digital data is screened both prior and subsequent to the transformation to identify those epochs which contain artifacts. During each update period, the frequency spectra for each channel from the artifact-free epochs are averaged. The amplitudes of each averaged frequency spectrum for frequencies in each of four basic frequency bands are then summed. The result is an amplitude value for each of the four frequency bands at each channel. The four amplitude values are used to update a display which contains a graphical representation of the amplitude in each of the four bands in a different color. The amplitude values are also compared with previously recorded base line values, and an audible or visual warning indication is provided when predetermined variances from the base line values occur.

High-resolution electron time-of-flight apparatus for the soft x-ray region

Abstract: A gas-phase time-of-flight (TOF) apparatus, capable of supporting as many as six electron-TOF analyzers viewing the same interaction region, has been developed to measure energy- and angle-resolved electrons with kinetic energies up to 5 keV. Each analyzer includes a newly designed lens system that can retard electrons to about 2% of their initial kinetic energy without significant loss of transmission; the analyzers can thus achieve a resolving power (E/ΔE) greater than 104 over a wide kinetic-energy range. Such high resolving power is comparable to the photon energy resolution of state-of-the-art synchrotron–radiation beamlines in the soft x-ray range, opening the TOF technique to numerous high-resolution applications. In addition, the angular placement of the analyzers, by design, permits detailed studies of nondipolar angular distribution effects in gas-phase photoemission.