Methods and apparatus for reducing correlation sidelobe interference in seismic profiling systems
US4799201A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 16, 1983 |
| Grant date | Jan 17, 1989 |
| Priority date | — |
| Expiry date | Dec 16, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V1/375
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In seismic profiling systems utilizing sweeps of signals which change in repetition frequency during the transmission interval, interference results from a spurious correlation against an interfering sweep, usually produced by the first break reflection of a simultaneously transmitted sweep which is in the opposite sense for 3-D surveying or from another source. The first break interfering sweep repeats while correlating with time slipped replicas in surveying for deeper and deeper reflecting interfaces and appears as correlation sidelobe interference which has a significant contribution to the correlator output only when the interfering sweep and the replica are in a condition where their frequencies are identical or nearly so. This condition is known as stationary phase. The interference is reduced without adversely affecting the correlation integral of the sweep reflected from the reflection interface of interest by muting either input to the correlator for a short period of time surrounding the points of stationary phase between the interfering sweep from the first break and the replica or by selectively pre-whitening the received sweep signal prior to correlation. This action …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.