Spectrum analyzer

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

Microwave Analog Real-Time Spectrum Analyzer (RTSA) Based on the Spectral–Spatial Decomposition Property of Leaky-Wave Structures

Abstract: A novel analog real-time spectrum analyzer (RTSA) for the analysis of complex nonstationary signals (such as radar, security and instrumentation, and electromagnetic interference/compatibility signals) is presented, demonstrated, and characterized. This RTSA exploits the space-frequency mapping (spectral-spatial decomposition) property of the composite right/left-handed (CRLH) leaky-wave antenna (LWA) to generate the real-time spectrograms of arbitrary testing signals. Compared to digital RTSAs, it exhibits the advantages of instantaneous acquisition, low computational cost, frequency scalability, and broadband or ultra-wideband operation. The system is demonstrated both theoretically by a commercial full-wave simulator and an efficient Green's function approach and experimentally by a parallel-waveguide prototype including a metal-insulator-metal CRLH LWA, 16 patch antenna probe detectors circularly arranged around the LWA, and a digital oscilloscope performing analog/digital conversion and time-domain acquisition before the postprocessing and displaying of the spectrogram. The system is tested for a large diversity of nonstationary signals and generates, in all cases, spectrograms that are in excellent agreement with theoretical predictions. The fundamental tradeoff between time and frequency resolutions inherent to all RTSA systems is also discussed, and an interchangeable multi-CRLH LWA solution is proposed to handle signals with different time durations.

Radiation filter, spectrometer and imager using a micro-mirror array

Abstract: A spectrometer (10) includes a two-dimensional array of modulatable microm-irrors (18), a detector (20), and an analyzer (22). The micro-mirrors are positioned for receiving individual radiation components forming a part of a radiation source. The micro-mirrors are modulated at different modulation rates in order to reflect individual radiation components at known and different modulation rates. The micro-mirrors combine a number of the reflected individual radiation components and reflect them to the detector. The detector receives the combined radiation components and creates an output signal. The analyzer is coupled to the detector to receive the output signal and to analyze at least some of the individual radiation components making up the combined reflection. By using a micro-mirror array that modulates the radiation components at different rates, all of the radiations components can be focused onto a single detector to maximize the signal-to-noise ratio of the detector.

Design and operation of ETA, an automated ellipsometer

Abstract: The design and operational features are described for a computer-assisted ellipsometer (called ETA for Ellipsometric Thickness Analyzer), developed to provide reliable. real-time measurement of field-effect transistor gate insulator thickness in a manufacturing environment. ETA illuminates the sample with light of fixed polarization and uses a rotating analyzer to measure the polarization of the reflected light. Sample alignment is done automatically by ETA, so that usually no operator adjustments are required. Fourier analysis of the light transmitted by the analyzer is used to reduce noise and enhance measurement precision. In its normal mode of operation (incident light linearly polarized at 45°), ETA can measure single and double-layer films of SiO2, and Si3N4, in the thickness range of 300 to 800 A with precision comparable to that of conventional ellipsometers. Other modes of operation, which make use of a fixed-position compensator in the incident light path, allow precise measurement of thin films (0 to 300A) and permit use of ETA as a general-purpose ellipsometer. The typical time interval required for wafer alignment, data acquisition, analysis and recorded output of film thickness is about five seconds, and the measurement reproducibility is typically about 1A.

Medical sensor with amplitude independent output

Abstract: The present invention provides a medical sensor for detecting a blood characteristic. The sensor includes a transducer for producing an analog signal related to the blood characteristic. The analog signal is converted into a transmission signal which is in amplitude-independent form for transmission to a remote analyzer. In one embodiment, a current-to-frequency converter converts a signal from a pulse oximeter sensor into a frequency signal which can be transmitted over a transmission line to a remote pulse oximeter.