Apparatus and method for the detection and measurement of liquid water and ice layers on the surfaces of solid materials
US5686841A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1995 |
| Grant date | Nov 11, 1997 |
| Priority date | — |
| Expiry date | Dec 13, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08G1/096783
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An embodiment of the present invention is a roadway sensor for surface installation in a hole such that a thin ceramic contact sensor may be used to measure and cross-compare fundamental physical antenna parameters of the space immediately above a roadway or bridge surface. Measurements are combined by a microprocessor to discriminate between dry pavement, water (rain), snow and ice above the sensor head. Ambient surface temperature, water depth and ice/slush conditions are determined to estimate any hydroplaning hazard and ice/antifreeze/water mixtures. The sensor comprises an antenna that exhibits a resonant frequency and an input admittance including a real term; a Maxwell bridge coupled to the antenna for detecting the resonant frequency, input admittance and real term; and a frequency sweeping oscillator for driving the antenna at a plurality of frequencies proximate in frequency to the resonant frequency. A phase sensitive detector determines an attenuation rate and phase and thereby is able to extract a conductivity (.sigma.) and a dielectric (.epsilon.) measurement. The microprocessor relates the conductivity and dielectric measurements to yield, for example, a pair of esti…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.