USA As Represented by Secretary of the Navy

Herbert V Hitney

Jack R Olson

Kenneth D Anderson

Juergen H Richter

Richard A Paulus

Murray H Schefer

A system and method are provided for determining in real time, the radio refractive index structure of the atmosphere. The method may be characterized as comprising the steps of: transmitting a radio frequency signal over a predetermined path; receiving the radio frequency signal; detecting the strength of the radio frequency signal; determining a radio propagation factor from the strength of the radio frequency signal; determining a base height function of the atmosphere; and employing the radio propagation factor in the base height function to determine a trapping layer base height of the atmosphere which represents the radio refractive index structure of the atmosphere.

Method and system for inferring the radio refractive index structure of

Radio-wave propagation is rapidly predicted by a hybrid computational method that uses Ray Optics techniques to calculate radio field strength above a limiting radio-wave ray, Parabolic Equation techniques to calculate radio field strength below the limiting radio-wave ray and below a predetermined altitude, and a newly created Extended Optics method to compute radio field strength in an area of the atmosphere below the limiting radio-wave ray and above the predetermined altitude. Rays in the extended optics area are initialized from the elevation angle that rays traced through the parabolic equation area make with the predetermined altitude. Where reflected, direct or origin created rays do not exist within the parabolic equation area, the elevation angle for the ray that does exist at the furthest range (optical limit) is used to initiate ray tracing in the extended optics area for ranges beyond the optical limit. Where the refractive index varies along the predetermined altitude, adjustments to the elevation angle used to initialize rays within the extended optics area are made. Propagation factors, determined through the Parabolic Equation method, are assigned to the rays traced through the extended optics area based upon the propagation factors in existence at the predetermined altitude. Field strength or propagation loss within the extended optics area is calculated from an interpolation between propagation factor values assigned to the extended optics rays.

High speed method for predicting radio-wave propagation

An air/sea temperature probe is disclosed which can be deployed from a moving ship to detect the temperature profile of the atmosphere and ocean beyond the thermal influence of a ship. The probe includes a temperature transducer which utilizes a bifilar wire that provides a very quick air temperature time constant. The transducer is mounted within a radiation shield having low thermal conductance to minimize thermal and solar radiation contamination and is coupled to a signal processing network. In operation, the probe is deployed from a ship and provides temperature telemetry via an electrical data link coupled between the signal processing network and a receiving transducer located onboard the ship.

Air/sea temperature probe

A method and means of assessing the effects of the lower atmosphere on the performance capabilities of a variety of electromagnetic systems. Environmental data is entered manually into a computer by means of a keyboard or on digital tapes in cassette form. A mathematical model is selected and will generate the type of display desired when the required information and a specific electromagnetic system of interest is selected. A display will appear on the graphics-display screen from which hard copies can be made for use in deploying and making tactical decisions as to stationing of assets.

Integrated refractive effects prediction system

In a method for inferring the refractive index profile of the lower atmosphere a signal pattern comprising interference nulls is observed by receiving a signal from a satellite transmitter over a period of time. Hypothetical signal patterns are successively calculated by hypothesizing the validity of different refractive index profiles and compared with the observed signal pattern until one of them matches the observed signal pattern to within a selected limit of error.

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San Diego, CA, United States of America

Herbert V Hitney