INTRODUCTION
GENERAL DESCRIPTION
0311385 Issue : April 1999
1-2
Digital Pilot Generator (DPG)
The DPG is connected to the data acquisition system through an Ethernet link and
acts as a master control unit for the VE 432 system.
The DPG can be :
- fully integrated with the SN 388 acquisition system,
- or connected to any other type of acquisition system, using its own graphic
user interface.
- or used as Slave unit to control acquisition start on a remote (slave)
acquisition system.
Digital Servo Drive (DSD)
Installed in each vibrator, the DSD performs real time control of the vibrator ground
force, computes and transmits a complete attribute set for a QC data base.
Maintenance modes are available that make it possible to easily check the
performance of the vibrator hardware and the GPS system.
VE432 Main features
• • Signal generation
Up to 4 different simultaneous pilot signals are generated by the DPG.
A pilot or a sweep signal is generated from an operator-defined library of 32 basic
signals combined with up/down, phase shift parameters.
Basic signals are defined by their frequency range, frequency vs. time law, time
duration, tapers and amplitude vs. time law.
A single DPG can handle up to 4 vibrator fleets with a total of 28 vibrators.
• • Digital vibrator control
By an automatic identification procedure, the VE432 digital model is adapted to any
type of vibrator without the need for manual adjustment.
The fully digital auto-adaptive servomechanism performs an optimal control which
minimizes the phase and distortion and maximizes the fundamental output.
Optimal digital control allows :
- fast sweep rate,
- combination of sweep segments with no dead time, used in cascaded
(*)
- pseudo-random sweeps, for environmentally friendly vibration,
unlimited variety of user-defined sweeps (custom sweep type).
Exxon Patent
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