Signal generation apparatus and method for seafloor electromagnetic exploration
US7187569B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 2, 2002 |
| Grant date | Mar 6, 2007 |
| Priority date | — |
| Expiry date | Oct 2, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M5/27
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An apparatus for generating electronic signals for application in subsea electromagnetic exploration. A surface generated high-voltage low-current source signal stabilized at a first frequency is supplied to a deep-tow vehicle (18) via an umbilical cable (16). The high-voltage low-current signal is transformed at the deep-tow vehicle to a high-current low-voltage a.c. signal by a transformer (52) within a cycloconverter (30). A semiconductor relay bridge (104) provides switchable rectification of the high-current low-voltage a.c. signal to provide a quasi-square wave at a second frequency, lower than the first frequency, for supply to a transmitting antenna (22) towed by the deep-tow vehicle. The times of the rectification switching are dependent on zero crossings of the high-current low-voltage a.c. signal. Allowable rectification switching times may be gated to occur only within pre-determined time windows to avoid noise-induced zero-crossing switching. The apparatus allows multiple transmission frequencies to be derived from a single stabilized source and improves spectral integrity by avoiding rectification switching at zero-crossings not occurring at the first frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.