Processing of the laser Doppler velocimeter signalsThe laser Doppler velocimeter (LDV) is a probeless technique that provides a remote measurement of mean and fluctuating velocities. The measurement is actually obtained from small particles embedded in the flow which scatter light from an illuminating laser beam interference pattern. A portion of this scattered light is collected by a photomultiplier which yields an electronic signal whose frequency is directly proportional to the velocity of the small particles. The purpose of this paper is to describe and critically compare three techniques most used to process this electronic signal. These techniques are: (1) spectrum analyzer - a frequency scanning filter (frequency domain instrument), (2) wide-band frequency tracker - a frequency lock loop (frequency domain instrument), and (3) high-speed frequency counter - an interval timer (time domain instrument). The study determines the ability of each technique to process the LDV signal and yield velocity data to be used in determining the flow characteristics.
Document ID
19740043748
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Meyers, J. F.
Feller, W. V. (NASA Langley Research Center Hampton, Va., United States)
Date Acquired
August 7, 2013
Publication Date
January 1, 1973
Subject Category
Instrumentation And Photography
Meeting Information
Meeting: ICIASF ''73; International Congress on Instrumentation in Aerospace Simulation Facilities