2 edition of signal processor design for laser doppler anemometry found in the catalog.
signal processor design for laser doppler anemometry
Calvin Keller Kendall
Written in English
|Statement||by Calvin Keller Kendall.|
|The Physical Object|
|Pagination||x, 107 l. :|
|Number of Pages||107|
Specifically, in laser Doppler anemometry (LDA) it is usual to receive bursts with a poor signal-to-noise ratio, yet high accuracy is required for the measurement. In recent years special attention has been paid to the problem of monitoring the temporal evolution of turbulent by: 4. As a consequence the signal can be split into two parts - a low frequency part called the 'pedestal' and a high frequency part that actually contains the Doppler signal. Modern signal processors use digital technology to analyze each burst and extract the frequency and thus velocity at that instant.
The minimum number of samples that must be taken from a sinusoidal signal affected by white Gaussian noise, in order to find its frequency with a predetermined maximum error, is derived. This analysis is of interest in evaluating the performance of velocity-measurement systems based on the Doppler effect. Specifically, in laser Doppler anemometry (LDA) it is usual to receive bursts with a poor Cited by: 4. Doppler anemometry signal processing. An appropriate design of the system forces the fringes’ Laser Doppler anemometry is widely used to measure the local, time-dependent velocities.
Laser Doppler Anemometry The basic principles of laser Doppler anemometry (LDA) are summarized here. For a more comprehensive treatment of these principles, the reader is referred to standard text books such as those by Durst et al. Durst76, Durrani and Greated Durrani77, Somerscales Marton81, Absil Absil95, and Albrecht et al. Albrecht03 Aspects of LDA that are typical for a three-component. The laser Doppler anemometer signal structure is experimentally studied for measuring the flow velocity in optically inhomogeneous media, such as blood and suspensions of scattering particles. The results of measuring the whole and diluted blood flow velocity in channels with a rectangular cross section are presented.
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Laser Doppler anemometer signal processing for blood flow velocity measurements at the angle 14°. The precision of the beam coincidence is determined by the alignment of the LDA optical system and the accuracy of the prism by: 6.
A number of signal processing schemes are discussed for the Laser Doppler Anemometer and the Time-of-Flight Laser Anemometer. Special emphasis is placed on time-resolved measurements with a tracking processor.
The essential statistical properties of the detector signal (s) is (are) by: 1. TABLE OF CONTENTS: (1) Introduction (2) Principles of Optics (3) Scattering phenomena and optical systems (4) Basic principles of laser-Doppler anemometry (5) Components of optical systems (6) Introduction to signal processing (7) Signal processing frequency analysis (8) Signal processing frequency-tracking demodulation (9) Signal processing by counting (10) Scattering particles: Cited by: In laser Doppler and phase Doppler anemometry the detection and identification of the Doppler signal in the noisy background signal is essential in order to perform fast and reliable measurements.
In the present paper two novel concepts for Doppler signal identification are by: A historical review of laser Doppler anemometry is given, its relationship to other optical techniques is examined, and principles of geometrical, physical, and quantum optics are outlined.
Light scattering is analyzed, the optical measurement of particle velocity is explained physically, and principles of laser Doppler anemometry are : F. Durst, A. Melling, J. Whitelaw. The system is capable of measuring Doppler frequencies up to 5 MHz and of data acquisition rates up todata points per second.
The signal processor includes analog amplifiers, a Schmitt trigger, and a preprocessor for data validation and : C. Kendall, D. Stock, H. Rigas. Laser Doppler Anemometry [LDA] three different processing schemes can be used to determine fd.
A 'counter' processor first isolates the modulation in the burst using a high-pass filter, and then counts the number of zero-crossings in a unit of time. A 'spectrum analyzer' calculates the Fourier transform of the burst signal, and then selects.
Laser Doppler anemometry (LDA) is widely used for fluid mechanics but may also provide measurements of the acoustic particle velocity. The validation of its use in acoustics, which is being achieved, requires knowledge of the appropriate data processing parameters.
In order to understand their effects, an experiment is conducted in which LDA measures structural : Sylvain Poggi, Bruno Gazengel, Jean‐Christophe Valière, Anne‐Marie Bruneau. Signal Processing. The output signal of the photodiode may be processed using an amplifier, an A/D-converter and a digital processor.
It is useful to apply an amplifier that allows for correction of bias in the signal since the intensity of the scattered light may vary notably for different circumstances. CONFERENCE PROCEEDINGS Papers Presentations Journals.
Advanced Photonics Journal of Applied Remote SensingCited by: 2. Laser Doppler velocimetry (LDV), which is also sometimes called laser Doppler anemometry (LDA), has been applied extensively to characterise liquid flow, mixing, and energy dissipation in a variety of flow situations, including stirred bioreactors.
The high spatial resolution of LDV combined with its ability to follow rapid fluctuations in velocity make it an important tool for the study of turbulence. Signal processing schemes for laser Doppler anemometers and time-of-flight laser anemometers are discussed; particular attention is given to time-resolved measurements made with a tracking processor.
For optimizing a signal processor, the maximum likelihood estimator is employed. Types of tracking processors described in this paper include. A brief survey is given of the principles and present state of the art in laser Doppler anemometry.
Both the optical and signal-processing aspects are treated in some detail. The comparative features and special problems associated with the various methods of interpreting the Doppler signals are discussed, with particular reference to the more Cited by: The theme of the thesis is Advanced Signal Processing Techniques for Pulsed-Doppler Radar.
As the title suggests, the paper deals with techniques, from a very low level point of view, that allow a radar to detect a target, estimate its parameters and track it in a noisy environment.
as laser-Doppler anemometry (LDA) or particle image velocimetry (PIV), HWA retains a number of distinct advantages which ensure its present and future use. Hans Bruun has written a comprehensive book which provides a state-of-the-art survey on developments and use of HWA.
In many details the book complements. Laser Doppler Anemometry: Main page / List of experiments / Relevant topics: Signal processing and data analysis. The signal is composed of low frequency background noise, the Doppler frequency and high frequency components in the order of the frequency of the laser beam.
The low frequency noise can be the result of some other light source. A variety of methods have been developed to obtain acurate frequency estimates from laser Doppler velocimetry (LDV) signals. Rapid scanning and fiber optic LDV systems require robust methods for extracting accurate frequency estimates with computational efficiency from data with poor signal-to-noise ratios.
These methods typically fall into two general categories, time domain Cited by: PROCESSING OF STOCHASTIC SAMPLED DATA IN LASER DOPPLER ANEMOMETRY Holger Nobach Dantec Measurement Technology A/S, Tonsbakken 16–18, DK Skovlunde, Denmark.
@ ABSTRACT The laser Doppler anemometry (LDA) as anon-intrusive technique of velocity measurements is widely used in the study of turbulent ﬂow Size: KB. Laser Doppler velocimetry, also known as laser Doppler anemometry, is the technique of using the Doppler shift in a laser beam to measure the velocity in transparent or semi-transparent fluid flows or the linear or vibratory motion of opaque, reflecting surfaces.
The measurement with laser Doppler anemometry is absolute and linear with velocity and requires no pre-calibration. Laser Doppler anemometry facility.
A brief survey is given of the principles and present state of the art in laser Doppler anemometry. Both the optical and signal-processing aspects are treated in some detail. The comparative features and special problems associated with the various methods of interpreting the Doppler signals are discussed, with particular reference to the more.
Deighton, M. O. Design principles of a frequency tracker for laser anemometry. Deighton, M. O. & Sayle, E. A. An electronic tracker for the continuous measurement of Doppler frequency from a laser by: A dedicated microprocessor system has been developed exclusively to control and reduce data from a two‐component laser Doppler velocimeter (LDV) which uses counter‐type signal processors.
The Author: D. V. Srikantaiah, T. Philip, W. W. Wilson.Laser Doppler anemometry (LOA) in compressible flows offers the advantages of unambiguous signal interpretation (the laser Doppler anemometer senses VelOClty Only) and nonlntruslveness. of the LOA is its ability to accurately measure the normal or vertical velocity fluctuations in regionsFile Size: KB.