Airborne microwave path modeling system
OwnerEthelbert P. Elmore, Jr.inventor
Life of this patent
Estimating the term…
Abstract
An airborne geophysical measurement and recording system and apparatus in which radar signals are focused onto terrain below an aircraft flying in a straight line between microwave tower sites. The echo signals are detected and signals produced and recorded on a strip chart recorder indicating path profile and terrain reflectivity. In addition, atmospheric pressure, temperature and humidity data are recorded as functions of aircraft altitude, so that atmospheric refractivity gradients can be calculated, either by an on-board computer or later, and this factor taken into account during path design or performance simulation.
Claims6
An airborne geophysical measurement and recording system comprising:
- radar means for producing a focused radar signal, directing said signal to a terrain area below said aircraft and successively receiving a return signal from said terrain area,
- a linear range circuit connected to the output of said radar means for successively producing radar range signals from said return signal indicating the highest obstruction in said terrain area,
- an amplitude circuit connected to the output of said radar means for producing an echo magnitude signal which varies as a function of the maximum echo magnitude of said return signal,
- temperature means for detecting the atmospheric temperature and producing a temperature signal which varies as a function thereof,
- humidity means for detecting atmospheric humidity and producing a humidity signal which varies as a function thereof,
- aircraft height means for detecting aircraft altitude and producing an altitude signal,
- profile means for producing a profile signal which varies as a function of the difference between said range signal and said altitude signal,
- reflectivity means for producing a reflectivity signal which varies as a function of said echo magnitude signal,
- pressure means for detecting absolute atmospheric pressure and producing a pressure signal,
- means for recording said temperature signal, said humidity signal, said pressure signal, said altitude signal, said profile signal and said reflectivity signal, and
- means connected to said pressure means, and wet temperature means for producing from a plurality of data points taken at different altitudes a refractivity gradient dN/dh according to the relation
- N = 77.6 P/T + 3.73 .times. 10.sup.5 e/T.sup.2 where N is the radio refractivity in parts per million exceeding unity, h is the altitude at which the data points are taken, P is a data point representing the atmospheric pressure in millibars, T is a data point representing the temperature in degrees Kelvin, e is a data point representing the partial pressure of water vapor in millibars, and dN/dh is the refractivity gradient per kilometer of height in the lower air layer traversed by the microwave beam.
Dependencies are inferred from the claim text.