Differential correlation analyzer
US4787252A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1987 |
| Grant date | Nov 29, 1988 |
| Priority date | — |
| Expiry date | Sep 30, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/7082
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A flow meter, or flow path intervalometer, transmits a transmission signal modulated with digital pseudo-noise or similar code. The received signal is correlated with the transmitted signal at successive times to produce a correlation function having a peak at a time to equal to the propagation time. The code is selected such that the side lobes of the correlation function are small. An interpolator determines a precise time of maximum correlation. In one embodiment, upstream and downstream correlation functions are defined and are correlated to determine an upstream-downstream propagation time difference interval .DELTA.t. In a preferred embodiment the digital code is a Barker code, and the transmitted signal is a finite interval wave which is phase modulated by the Barker code. In another embodiment, the received signal is a reflected signal which is range gated so as to represent flow data originating from a desired region within the conduit. The signal is sampled in phase quadrature and transformed to determine its frequency domain representation, and the devide derives local flow rate information from Doppler information. In yet another embodiment, a plurality of transducers a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.