Method and apparatus for distance measurement using electromagnetic waves
US5044744A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 29, 1990 |
| Grant date | Sep 3, 1991 |
| Priority date | — |
| Expiry date | May 29, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S17/87
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Times t.sub.1 and t.sub.2 required for two electromagnetic waves having different wavelengths to propagate from a reference point to a target point are measured. Necessary meteorological conditions along the path are also measured to determine refractivities N.sub.1 and N.sub.2 of the path for the two electromagnetic waves as: EQU N.sub.1 =.alpha..sub.1 .multidot..rho..sub.s +.beta..sub.1 .multidot..rho..sub.w EQU N.sub.2 =.alpha..sub.2 .multidot..rho..sub.s +.beta..sub.2 .multidot..rho..sub.w where .rho..sub.s and .rho..sub.w are densities of dry air and water vapor in the path, respectively. Length of the path D is calculated using the following formula: EQU D=[t.sub.1 +{(.alpha..sub.1 +.beta..sub.1 .multidot..rho..sub.w /.rho..sub.s).multidot.(t.sub.2 -t.sub.1)}/{(.alpha..sub.1 +.beta..sub.1 .multidot..rho..sub.w /.rho..sub.s)-(.alpha..sub.2 +.beta..sub.2 .multidot..rho..sub.w /.rho..sub.s)}].multidot.C. where C is the speed of an electromagnetic wave in vacuum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.