Government of the United States of America, As Represented by the Secretary of Commerce

James H Churnside

James R Jordan

Alfred J Bedard, Jr

Steven F Clifford

Randall T Nishiyama

Steen G Hanson

Evgenii P Gordov

Paul Ernest Johnston

Viktor M Orlovskii

Signal processing is used to detect transient signals in the presence of noise. Two embodiments are disclosed. In both embodiments, the time series from a remote sensor is broken into a number of short time series. The power spectrum of each short time series are then calculated along with the mean noise level. The moments of each peak in every power spectrum are calculated and the peak with the largest power selected from each power spectrum. A histogram of the moments from these selected peaks is generated and normalized to become a measured PDF. In addition, a pre-determined PDF is derived, in the same method as above, from theoretically calculated noise, numerically simulated noise, or measured noise. Comparison between the measured and pre-determined PDF's establish the detection of a transient signal. The first embodiment compares the area between the measured and pre-determined PDF's against a threshold to determine detection. In a second embodiment, the differences between the measured and pre-determined PDF's are weighted and summed to form a score. This score is compared to a threshold to determine detection.

Detection of transient signals in doppler spectra

An autodyne lidar system utilizing a hybrid laser. The hybrid laser inclu a continuous wave (CW) optical gain section and a pulsed optical gain section in the same laser cavity. A highly reflecting mirror and a partially reflecting mirror, also called an output coupler, form the ends of a laser cavity. Both the continuous wave optical gain section and the pulsed gain section are positioned in the laser cavity. A detector is position in such a manner so as to observe the light reflecting through the cavity.

Autodyne lidar system utilizing a hybrid laser

An apparatus and method are disclosed for reducing electromagnetic or acoustic energy scattered in both the near and more generalized vicinity of a source thereof by various phenomena including atmospheric and weather-related effects and diffraction at the top edge of heretofore known barriers. The apparatus includes a member configured for engagement with the top edge of a barrier, with the member having a patterned edge defining a plurality of portions jutting away from the top edge of the barrier and in a direction having a component toward the source, preferably substantially in a more or less horizontal plane with the top edge.

Apparatus and method for reducing acoustic or electromagnetic energy in

The disclosed invention is a measurement device for use in determining wind turbulence in the atmosphere, such as the cross-wind velocity and strength of refractive turbulence in a localized region. In the preferred embodiment, the device is comprised of: a telescope for collimating the light received from the light source, the telescope placed in front of a pair of spatially filtered optical receivers and focussed at infinity; a pair of gratings; a collecting lens, placed behind the gratings to collect the spatially filtered light; a photodetector to collect the light; an amplifier to amplify the signal received from the photodetector, and; a spectrum analyzer to analyze the interference pattern created by the gratings. The device uses the information contained in the light as it is scattered into its various Fourier components as the light passes through the atmosphere. This information, by means of the two filters, is processed to determine the turbulence, whose wavenumber is the difference of the spatial filter wavenumber of the first and the second spatial filters.

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Boulder, CO, United States of America

James H Churnside