Measured Spectral Extent of L- and X-Band Radar Reflections from Wind- Blown Trees

Abstract

Measurements of the spectral content of L-and X-band radar reflections from seleral resolution cells containing wind-blown trees are examined under a wide variety of typical wind conditions. Most of the discernible energy (i.e., within 60 dB of the peak zero-Doppler level) occurs in the spectra at Doppler winly days. The rates of decay of energy with increasing Doppler velocity in the tails of the spectral distributions at spectral off-sets well removed from zero often appear to be approximately exponential. Estimates of rates of exponential decay in the spectral tails as a function of windspeed are provided in three regimes of windspeed.

Multifrequency Measurements of Radar Ground Clutter at 42 Sites. Volume 2. Appendices A through D

“…We refer to this subsequent series of once-a-week measurements as Katahdin Hill (3). The measurements from the Katahdin Hill (3) activity are reported elsewhere [1].…”

“…On the raw CDC tape, clutter returns are uncalibrated and are given in terms of A/D counts. On the calibrated tape, however, for each pulse emitted, the coherent clutter return from each range gate is calibrated in absolute units of (radar cross section) 1 1 2 in both in-phase and quadrature channels. As our program evolved, we made two changes in our calibration algorithms (see Section A.3).…”

Vegetated Target Decorrelation in SAR and Interferometry: Models, Simulation, and Performance Evaluation

“…The Intrinsic Clutter Model (ICM) was first proposed by Billingsley and Larrabee in [16] for windblown Doppler Power Spectrum Density (PSD) of radar clutter observed from low grazing angles. The PSD is composed by two terms: a Dirac pulse, representing the stable contributions, loosely affected by wind, and a low-pass exponential decay, whose slope depends on the wind speed and the radar wavelength, λ:…”

“…This means that α is the -ratio between the stable power and the clutter, whereby β accounts for the spectral slope. The model has been found quite good over a very wide range of frequency bands from VHF to K, and for times up to hundreds of milliseconds [2,16,17]. Its validity has been widely acknowledged also for targets different from a forest.…”

Internal clutter motion impact on the long integration GEOSAR acquisition

“…Billingsley found a mathematical model for the power spectrum of the internal clutter motion [1] from experimental results with low-angle radar over vegetated areas that depends on the radar frequency and wind speed. This model presents two components, a stationary term (DC) and an exponential noise term (AC).…”