Fast Signal Analysis Research Articles

Dual-frequency modulation quartz crystal tuning fork-enhanced laser spectroscopy.

An innovative trace gas-sensing technique utilizing a single quartz crystal tuning fork (QCTF) based on a photoelectric detector and dual-frequency modulation technique was demonstrated for the first time for simultaneous multi-species detection. Instead of traditional semiconductor detectors and lock-in amplifier, we utilized the piezoelectric effect and resonant effect of the QCTF to measure the light intensity. A fast signal analysis method based on fast Fourier transform (FFT) algorithm is proposed for overlapping signal extraction. To explore the capabilities of this technique, a gas-sensing system based on two lasers having center emission wavelength of 1.653 µm (a DFB laser diode in the near-IR) and 7.66 µm (an EC QCL in the mid-IR) is successfully demonstrated for simultaneous CH4 spectroscopy measurements. The results indicate a normalized noise equivalent absorption (NNEA) coefficients of 1.33×10-9 cm-1W·Hz-1/2 at 1.653 µm and 2.20×10-10 cm-1W·Hz-1/2 at 7.66 µm, were achieved. This proposed sensor architecture has the advantages of easier optical alignment, lower cost, and a compactness compared to the design of a conventional TDLAS sensor using multiple semiconductor detectors for laser signal collection. The proposed technique can also be expanded to common QEPAS technique with multi-frequency modulation for multiple species detection simultaneously.

A spatial sampling based 13.3 Gs/s sample-and-hold circuit.

This paper presents a high-speed sample-and-hold circuit (SHC) for very fast signal analysis. Spatial sampling techniques are exploited with CMOS transmission lines in a 0.13 μm standard CMOS process. The SHC includes on chip coplanar waveguides for signal and clock pulse transmission, a clock pulse generator, and three elementary samplers periodically (L = 7.2 mm) placed along the signal propagation line. The SHC samples at 13.3 Gs/s. The circuit occupies an area of 1660 μm × 820 μm and consumes ~6 mW at a supply voltage of 1.2 V. The obtained input bandwidth is ~11.5 GHz.

Fast signal analysis in Rotating-Polarization CARS microscopy

AbstractRotating Polarization Coherent Anti-Stokes Raman Spectroscopy (RP-CARS) is a novel approach to CARS microscopy that takes advantage of polarizationdependent selection rules in order to gain information about molecule orientation anisotropy and direction within the optical point spread function. However, in the original implementation of this technique, the lockin amplifier-based acquisition was quite time demanding. Here we present a new software-based approach that permits a great speed-up in the RP-CARS images acquisition process.

Quality Monitoring System for Seismic While Drilling

In this paper a quality monitoring system for seismic while drilling (SWD) that integrates the whole process of data acquisition was developed. The acquisition equipment, network status and signals of accelerometer and geophone were monitored real-time. With fast signal analysis and quality evaluation, the acquisition parameters and drilling engineering parameters can be adjusted timely. The application of the system can improve the quality of data acquisition and provide subsequent processing and interpretation with high qualified reliable data.

Use of triboelectric probes for on-line monitoring of liquid concentration in wet gas–solid fluidized beds

The objective of this study was to validate the effectiveness of a novel method employing triboelectric probes for accurate on-line solid moisture measurements in fluidized beds. Liquid injections were conducted in a fluid bed of glass beads and the resulting solid moisture was monitored during the whole drying stage by acquiring triboelectric signals generated from several locations inside the bed. For various superficial gas velocities and amounts of injected liquid, the bed drying end point and the fraction of sprayed liquid involved in the formation of slow-vaporizing stable agglomerates were estimated performing fast signal analysis by means of the W statistic.

Software architecture of data acquisition control process during TJ-II operation

Data from the diagnostics on the TJ-II device will be collected by several independent systems linked to local area networks (LANs). Some of these systems will consist of digitizers based on well-known standards: CAMAC, VME, VXI, etc. Other allowable systems would be personal computers or workstations with direct control over a specific diagnostic. In principal, any equipment capable of being linked in a LAN can be used as a controller for data collection. All systems will be programmed from a central computer. In this computer, an application program will allow the set up of data acquisition in any system. This will be achieved by communicating systems through a network standard protocol: TCP/IP. The central computer will also centralize the database of discharges. For this purpose, immediately after a discharge, data will be sent from the autonomous systems to the main computer. The latter will coordinate data reception, organize discharge information, and compress data. Data will be transferred rapidly so all diagnostic signals will be available to users for immediate analysis. The computer processes outlined here will provide an application program to provide users with an interface for all operations related to data acquisition, fast signal analysis, and remote control of diagnostics. A second functionality will be the management of TJ-II discharge database.

Spectral analysis and discrimination by zero-crossings

We advance a coherent development of zero-crossing-based methods and theory appropriate for fast signal analysis. Quite a few ideas pertaining to zero-crossing counts found in the literature can be expressed and interpreted with the help of this more general setup. A central issue addressed in some detail is the fruitful connection which exists between zero-crossing counts and linear filtering. This connection is explored and interpreted with the help of a certain zero-crossing spectral representation, and is then applied in spectral analysis, detection, and discrimination. Zero-crossing counts in filtered time series are called higher order crossings. The theme of this work is that higher order crossings analysis provides a useful descriptive as well as an analytical tool that can in many respects match spectral analysis. To a great extent these two types of analysis are, in fact, equivalent, but each emphasizes a different point of view. Advantages offered by higher order crossings are great simplicity and a drastic data reduction.