Spectrum analyzer

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

Improved distortion analayzer for compensation apparatus of first-orderpolarization mode dispersion (PMD)

Abstract: The effect of polarization mode dispersion that an optical signal experiences as it propagates through an optical transmission fiber is compensated for at a receiver using a birefringent compensator, in which a distortion analyzer repeatedly examines the signal outputted by the compensator and causes the compensator to reduce the effect of such polarization mode dispersion based on the results of such examination.

LaserBreeze gas analyzer for noninvasive diagnostics of air exhaled by patients

Abstract: A laser gas analyzer has been designed for determining the composition of exhaled air by means of photoacoustic spectroscopy. The analyzer, based on a broadband optical parametric oscillator and photoacoustic detector, provides high-precision rapid analysis of the multicomponent composition of human exhaled air for dynamic estimation of the efficiency of treating bronchus and lung diseases.

Phase noise measurement of wideband microwave sources based on a microwave photonic frequency down-converter.

Abstract: An approach for phase noise measurement of microwave signal sources based on a microwave photonic frequency down-converter is proposed. Using the same optical carrier, the microwave signal under test is applied to generate two +1st-order optical sidebands by two stages of electro-optical modulations. A time delay is introduced between the two sidebands through a span of fiber. By beating the two +1st-order sidebands at a photodetector, frequency down-conversion is implemented, and phase noise of the signal under test can be calculated thereafter. The system has a very large operation bandwidth thanks to the frequency conversion in the optical domain, and good phase noise measurement sensitivity can be achieved since the signal degradation caused by electrical amplifiers is avoided. An experiment is carried out. The phase noise measured by the proposed system agrees well with that measured by a commercial spectrum analyzer or provided by the datasheet. A large operation bandwidth of 5–40 GHz is demonstrated using the proposed system. Moreover, good phase noise floor is achieved (−123 dBc/Hz at 1 kHz and −137 dBc/Hz at 10 kHz at 10 GHz), which is nearly constant over the full measurement range.

Acoustic Emission in the Frequency Domain

Abstract: A means for quickly and easily determining the broadband frequency content of acoustic bursts as short as 20 μs in duration has been developed using a video tape recorder and a standard spectrum analyzer. It is shown by examples from several tests on laboratory specimens and on large structures that the frequency content of an acoustic burst is related to the mechanism which produced it and is not affected substantially by the specimen size or by mode conversion due to multiple reflections in the structure. The frequency content of the burst can be changed in two ways, however: by the frequency-dependent attenuation of the propagation medium and in the cases where the medium is dispersive. Results of measurements on the effect of these factors in a variety of structures are given. Although acoustic emissions from many materials tend to be "white noise," several examples of acoustic emissions and exwaneous background noise bursts having distinctive frequency spectra are given which suggest possibilities for discriminating true acoustic emission signals from background noise on the basis of frequency content alone.

Hand-held, self-contained optical emission spectroscopy (OES) analyzer

Abstract: A hand-held, self-contained, battery-powered test instrument for analyzing composition of a sample includes an exciter for exciting at least a portion of the sample, a compact cross-dispersed spectrometer for receiving an optical signal from the excited portion of the sample and a processor for processing spectral data about the optical signal from the spectrometer. The exciter may include a spark generator and a counter electrode, a laser or other device for generating the optical signal from the sample portion. The spectrometer has a wavelength range broad enough to enable the test instrument to detect and determine relative quantities of carbon, phosphorous, sulfur, manganese, silicon, iron and other elements necessary to identify common alloys. The spectrometer includes a structural member made of a light-weight material having a small coefficient of thermal expansion (CTE). The spectrometer is dimensionally stable over a range of expected ambient temperatures, without controlling the temperature of the spectrometer.