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Article

Development of a GPS Forest Signal Absorption Coefficient Index

1
Department of Geography and Environmental Engineering, United States Military Academy, West Point, NY 10996, USA
2
School of Forest Resources and Conservation, University of Florida, Gainesville, FL 32611, USA
*
Author to whom correspondence should be addressed.
Forests 2018, 9(5), 226; https://doi.org/10.3390/f9050226
Received: 14 March 2018 / Revised: 19 April 2018 / Accepted: 20 April 2018 / Published: 25 April 2018
In this paper GPS (Global Positioning System)-based methods to measure L-band GPS Signal-to-Noise ratios (SNRs) through different forest canopy conditions are presented. Hemispherical sky-oriented photos (HSOPs) along with GPS receivers are used. Simultaneous GPS observations are collected with one receiver in the open and three inside a forest. Comparing the GPS SNRs observed in the forest to those observed in the open allows for a rapid determination of signal loss. This study includes data from 15 forests and includes two forests with inter-seasonal data. The Signal-to-Noise Ratio Atmospheric Model, Canopy Closure Predictive Model (CCPM), Signal-to-Noise Ratio Forest Index Model (SFIM), and Simplified Signal-to-Noise Ratio Forest Index Model (SSFIM) are presented, along with their corresponding adjusted R2 and Root Mean Square Error (RMSE). As predicted by the CCPM, signals are influenced greatly by the angle of the GPS from the horizon and canopy closure. The results support the use of the CCPM for individual forests but suggest that an initial calibration is needed for a location and time of year due to different absorption characteristics. The results of the SFIM and SSFIM provide an understanding of how different forests attenuate signals and insights into the factors that influence signal absorption. View Full-Text
Keywords: canopy closure; global positioning system; hemispherical sky-oriented photo; signal attenuation; geographic information system canopy closure; global positioning system; hemispherical sky-oriented photo; signal attenuation; geographic information system
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MDPI and ACS Style

Wright, W.; Wilkinson, B.; Cropper, W., Jr. Development of a GPS Forest Signal Absorption Coefficient Index. Forests 2018, 9, 226. https://doi.org/10.3390/f9050226

AMA Style

Wright W, Wilkinson B, Cropper W Jr.. Development of a GPS Forest Signal Absorption Coefficient Index. Forests. 2018; 9(5):226. https://doi.org/10.3390/f9050226

Chicago/Turabian Style

Wright, William, Benjamin Wilkinson, and Wendell Cropper Jr. 2018. "Development of a GPS Forest Signal Absorption Coefficient Index" Forests 9, no. 5: 226. https://doi.org/10.3390/f9050226

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