Reseach of well logging pulse data acquisition circuit based on universal serial bus

Key words:  universal serial bus (USB)  well logging  pulse signal  data acquisition  complex programmable logic device(CPLD)

Abstract:

A kind of well-logging pulse data acquisition system based on universal serial bus (USB) was designed.The well logging pulse data acquisition is driven by depth sub-system. And pulse code modem (PCM) telemetry interface is remained in the system. The system is composed of hardware design of chip microprocessor，firmware design of chip microprocessor， device driver and application software design. In hardware designing，complex programmable logic device ( CPLD) is used to control the gain of pulse signal and the discharge switch of peek-value holding circuit during pulse data acquisition，and is used to check out synchronous frame of PCM signal and convert the serial signal data to parallel data，which save system resource of chip microprocessor. Chip microprocessor controls the whole course of well logging pulse data acquisition system， and realizes USB communication，sends data to host computer when being required. The system passed examination in lab-oratory. Its transmission speed is up to 300 kb/s，and its control function is flexible. Also，the system can be extended easily.