Microwave level gaging system
US4044353A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 6, 1976 |
| Grant date | Aug 23, 1977 |
| Priority date | — |
| Expiry date | Aug 6, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S7/4065
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for measuring liquid level. A generated broad-band swept-frequency C.W. microwave signal (2-4 GHz) is upverted to a high frequency band signal (34-36 GHz), which is transmitted towards, and reflected from, a liquid surface. The reflected signal is downverted to the frequency band of the original generated signal, and then the phase difference between the original and downverted signals is measured by a microwave phase discriminator and a quantizer, which generates video pulses proportional to the total phase shift across the swept C.W. band. During an adjacent sweep in the same direction, the original signal is compared with a signal transmitted through a calibration cable equivalent to a known free-space path length. The unknown signal path to and from the liquid surface, can then be calculated by comparison of the video pulse train outputs during the CALIBRATE and OPERATE modes of operation, either by the ratio of the number of pulses, or the average time between pulses during each sweep. Alternately, the mode of operation can be switched several hundred times during a single sweep across the bandwidth, and the unknown signal path corresponding to a particu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.