Accession Number:

ADA279733

Title:

Study of Photon Correlation Techniques for Processing of Laser Velocimeter Signals

Descriptive Note:

Contractor rept.

Corporate Author:

SCIENCE APPLICATIONS INC ATLANTA GA

Personal Author(s):

• Mayo, William T., Jr.

Report Date:

1977-02-01

Pagination or Media Count:

112.0

Abstract:

The objective of this work was to provide the theory and a system design for a new type of photon-counting processor for low-level Dual Scatter laser velocimeter LV signals which would be capable of both the first-order measurements of mean-flow and turbulence-intensity and also the second order time statistics cross-correlation, auto-correlation, and related spectra. A general Poisson process model for low-level LV signals and noise which is valid from the photon- resolved regime all the way to the limiting case of non- stationary Gaussian noise was used. Computer simulation algorithms and higher order statistical moment analysis of Poisson processes have been derived and applied to the analysis of photon correlation techniques. A system design using a unique Dual Correlate and Subtract frequency discriminator technique is postulated and analyzed. Expectation analysis indicates that the objective measurements are feasible. Error analysis for the mean-flow case indicates that practical transonic wind tunnel measurements are possible with 100-1000 times less light than is required for burst-counter processors. A system design for a new high-speed photon processor for LV signals is provided.

Descriptors:

• *SIGNAL PROCESSING
• *PHOTODETECTION
• *LASER VELOCIMETERS
• LIGHT SCATTERING
• STOCHASTIC PROCESSES
• COMPARISON
• SIGNAL TO NOISE RATIO
• GAUSSIAN NOISE
• TURBULENT FLOW
• LOW LEVEL
• CORRELATION TECHNIQUES
• STEADY FLOW
• PHOTON CROSS SECTIONS

Subject Categories:

• Optical Detection and Detectors
• Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE