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Optical Engineering

Pseudorandom noise code-based technique for thin-cloud discrimination with CO2 and O2 absorption measurements
Author(s): Joel F. Campbell; Narasimha S. Prasad; Michael A. Flood
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Paper Abstract

NASA Langley Research Center is working on a continuous wave (cw) laser-based remote sensing scheme for the detection of CO2 and O2 from space-based platforms suitable for an active sensing of CO2 emissions over nights, days, and seasons (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multifrequency, intensity modulated cw laser absorption spectrometer operating at 1.57 μm for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a pseudonoise code-based technique for cloud and aerosol discrimination applications. The possibility of using maximum length sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated. Proof-of-concept experiments carried out using a sonar-based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths.

Paper Details

Date Published: 1 December 2011
PDF: 9 pages
Opt. Eng. 50(12) 126002 doi: 10.1117/1.3658758
Published in: Optical Engineering Volume 50, Issue 12
Show Author Affiliations
Joel F. Campbell, NASA Langley Research Ctr. (United States)
Narasimha S. Prasad, NASA Langley Research Ctr. (United States)
Michael A. Flood, NASA Langley Research Ctr. (United States)

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