Design of Synchronous Multi-channel High Performance Acoustic Data Acquisition Based on Ethernet Connection

In order to get more azimuthal information of formation anisotropy, the array of acoustic receiver is employed in latest acoustic logging tools. As a part of basic experimental apparatus of acoustic logging, a synchronous 32-channel high performance acoustic data acquisition with 16-bit resolution, 1MSPS and 32K sampling depth is designed. This system is based on principal and subordinate structure. The host PC and embedded front-end interconnect via Ethernet. The embedded front-end based on ARM-uClinux extends a self-define bus, applying the physical structure of the PC104 module, to access acoustic data acquisition modules. Each acquisition module has eight analog-to-digital converters. Acquisition modules share the same start conversion signal and low noise, high accuracy voltage reference. To isolate the noise of the embedded front-end from ADC circuit, high speed optcoupler is used to form a local high speed serial bus. System control logic and software design of host PC and embedded front-end are discussed. In addition, design of low noise, low power acoustic signal amplifier is described. This acquisition system has been used in three-dimensional acoustic logging detector design successfully.