Spectrum analyzer

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

Handheld characteristic analyzer and methods of using the same

Abstract: Disclosed is a portable handheld characteristic analyzer used to analyze chemical compositions in or near real-time. One method of using the analyzer to determine a characteristic of a sample includes directing the handheld characteristic analyzer at the sample, the handheld characteristic analyzer having at least one integrated computational element arranged therein, activating the handheld characteristic analyzer, thereby optically interacting the at least one integrated computational element with the sample and generating optically interacted light, receiving the optically interacted light with at least one detector arranged within the handheld characteristic analyzer, generating an output signal corresponding to the characteristic of the sample with the at least one detector, receiving the output signal with a signal processor communicably coupled to the at least one detector, and determining the characteristic of the sample with the signal processor.

Apparatus for controlling an internal combustion engine

Abstract: An apparatus for controlling an internal combustion engine comprises a transducer which detects acoustic emissions generated by the operation of the engine, and produces an output signal. The output signal is amplified, rectified and enveloped to produce an electrical signal. The electrical signal has its direct current component removed to leave the alternating current component of the electrical signal. The AC component of the electrical signal is rectified by a rectifier and the mean level of the AC component of the electrical signal is measured by a measurer. An analyzer monitors the mean level of the AC component of the electrical signal and sends a feedback signal to an ignition timing device of the internal combustion engine. The analyzer sends feedback signals such that the mean value of the AC component of the electrical signal lies in the region of a positive peak prior to the occurrence of preignition.

Spectrum analyzer having enterable offsets and automatic display zoom

Abstract: An input signal is mixed with sampling signals from oscillators which vary the frequency of the sampling signal from a first frequency to a second frequency. The resulting Intermediate Frequency (IF) signal is processed and digital values are stored in a memory in response thereto. Waveforms are then displayed which correspond to these frequency and amplitude values. Various input and display circuits facilitate the display and interpretation of these waveforms.

A Multiplexed Impedance Analyzer for Characterizing Polymer-Coated QCM Sensor Arrays

Abstract: This paper describes the development and evaluation of a custom-built impedance analyzer, which uses a multiplexing bridge circuit to characterize an array of polymer-coated quartz crystal microbalance (QCM) sensors. The analyzer is constructed on a single printed circuit board with minimum components and is sufficiently compact for integration into a handheld format. The custom-built device is used to observe the changes that occur in QCM sensors when experimental conditions such as polymer coating film thickness, odorant vapor pressure, and relative molecular mass are varied. An equivalent electric circuit for a QCM is used to model the conductance and susceptance data captured by the analyzer. The measured response of an array of QCM sensors demonstrates that the custom-built device is a suitable instrument for detecting different gases and understanding polymer-vapor interactions

Raman analyzer for sensitive natural gas composition analysis

Abstract: Raman spectroscopy is of significant importance in industrial gas analysis due to its unique capability of quantitative multigas measurement, especially diatomics (N2 and H2), with a single laser. This paper presents the development of a gas analyzer system based on high pressure Raman scattering in a multipass Raman cell and demonstrates its feasibility for real-time natural gas analysis. A 64-pass Raman cell operated at elevated pressure (5 bar) is used to create multiplicative enhancement (proportional to number of passes times pressure) of the natural gas Raman signal. A relatively low power 532-nm continuous wave laser beam (200 mW) is used as the source and the signals are measured through a cooled charge-coupled device grating spectrometer (30-s exposure). A hybrid algorithm based on background-correction and least-squares error minimization is used to estimate gas concentrations. Individual gas component concentration repeatability of the order of 0.1% is demonstrated. Further, the applicability of the technique for natural gas analysis is demonstrated through measurements on calibrated gas mixtures. Experimental details, analyzer characterization, and key measurements are presented to demonstrate the performance of the technique.