Simulation of Weatherlike Doppler Spectra and Signals
01 Jun 1975-Journal of Applied Meteorology (American Meteorological Society)-Vol. 14, Iss: 4, pp 619-620
TL;DR: In this article, a versatile algorithm to generate weather-like spectra of any desired shape is described, and applications are briefly discussed, and a variety of weather-related applications are discussed.
Abstract: A versatile algorithm to generate weatherlike spectra of any desired shape is described, and applications are briefly discussed.
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TL;DR: In this paper, a compact array of hot wire anemometers was used to measure intraoral air velocity with a vertical cross section at the rear of the mouth during sustained phonation of the vowel "I".
Abstract: Reproducible intraoral air velocity measurements were made with a compact array of hot wire anemometers moved laterally within a vertical cross section at the rear of the mouth during sustained phonation of the vowel "I". The results indicate "separated" flow patterns at variance with laminar flow of vocal tract vowel models.
353 citations
TL;DR: In this paper, the authors investigated the effect of echo signal power, mean Doppler velocity, and spectrum width on the performance of a weather radar system using maximum likelihood (ML) solutions.
Abstract: Estimators of echo signal power, mean Doppler velocity, and spectrum width are investigated. Maximum likelihood (ML) solutions can improve the estimate variances by an order of magnitude over those by the autocovariance or the Fourier method. However, the required computations are excessive for routine implementations on weather radars. Spectrum power estimation together with two conventional methods of mean Doppler and width estimation are reviewed. Several results previously not available are presented.
251 citations
TL;DR: In this article, the first two power spectrum moments from the pulse pair covariance are analyzed and the mean frequency estimation from interlaced pulse pairs is compared to provide a continuum of statistics from equispaced tightly correlated to statistically independent pulse pairs.
Abstract: Estimates statistics of the first two power spectrum moments from the pulse pair covariance are analyzed. The input signal is assumed to be colored Gaussian and the noise, white Gaussian. Perturbation formulas for the standard deviation of both mean frequency and spectrum width are applied to a Gaussian shaped power spectrum, and so is a perturbation formula for the bias in the width estimate. Mean frequency estimation from interlaced pulse pairs is presented. Throughout this study, estimators from independent, spaced, and contiguous pulse pairs are compared to provide a continuum of statistics from equispaced tightly correlated to statistically independent pulse pairs.
203 citations
TL;DR: The theory of the Cramer-Rao lower bound (CRLB) and maximum-likelihood (ML) estimators is summarized in the context of a heterodyne lidar and the asymptotic bounds developed in the radar literature should not be used as approximations for the correct expression in lidar applications at intermediate signal levels.
Abstract: The theory of the Cramer-Rao lower bound (CRLB) and maximum-likelihood (ML) estimators is summarized in the context of a heterodyne lidar. Numerical experiments are described that indicate the scaling of this CRLB with parameters such as the signal bandwidth and the level of noise. This CRLB is also compared with the CRLB of a highly idealized noiseless direct detection system using photon counting. It is found that the asymptotic bounds developed in the radar literature for the heterodyne CRLB should not be used as approximations for the correct expression in lidar applications at intermediate signal levels. Moreover, the variance of the ML estimator may be greater or even less than the heterodyne CRLB, depending on the mechanism leading to the departure from the bound. >
193 citations
TL;DR: In this article, the authors developed an ultrawide-band (UWB) coherent random noise radar operating over the 1-2 GHz frequency range, which achieved phase coherence by using heterodyne correlation of the received signal with a time-delayed frequency-shifted replica of the transmit waveform.
Abstract: The University of Nebraska has developed an ultrawide-band (UWB) coherent random noise radar operating over the 1-2 GHz frequency range. The system achieves phase coherence by using heterodyne correlation of the received signal with a time-delayed frequency-shifted replica of the transmit waveform. Knowledge of the phase of the received signal and its time dependence due to target motion permits the extraction of the mean Doppler frequency from which the target speed can be inferred. Theoretical analysis, simulation studies, and laboratory measurements using a microwave delay line showed that it was possible to estimate the Doppler frequency from targets with linear as well as rotational motion. Field measurements using a photonic delay line demonstrated the success of this technique at a range of about 200 m at target speeds of up to 9 m/s. Analysis shows that the accuracy with which the Doppler frequency can be estimated depends not only on the phase performance of various components within the system, but also upon the random nature and bandwidth (BW) of the transmit waveform, and the characteristics of unsteady target motion.
134 citations
Cites methods from "Simulation of Weatherlike Doppler S..."
...Using the approach in [6], noise was introduced in the received waveform and Doppler frequency was estimated at different SNR’s and then averaged over 1000 samples....
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