Introduction

By clamping a transducer assembly onto the stimulation line used during well stimulation treatments, the placement of radioactive tracers can be monitored. The design of the computer data acquisition system used to monitor the radio isotope injection requires an understanding of basic data acquisition hardware and software. The design of the data acquisition system also requires an accurate specification of requirements in light of available options. The system discussed provides real-time feed back for operational quality control.

General Overview of PC Data Acquisition Collection and recording of relevant information in a systematic fashion for later reference and analysis can be referred to as data acquisition. Data measurements may also be used to provide a control function, in that a decision and response may be based upon observed data. Personal computers ("PC's") can facilitate and automate these activities. Using a PC for the acquisition of data may be as simple as entering information into a PC application such as a spreadsheet or data base. However, the term "PC data acquisition" normally applies to a more specialized case where data values are measured by a sensor device and then the sensor information is converted to a digital format by special hardware and software so that the PC can read and record the information (figure 1). Additional hardware and software may also be used to translate instructions (signals) from the PC to external devices for control purposes. Data acquisition and control systems may be thought of as a bridge between the outside world and the PC.

Most real-world sensors generate a continuum of signal levels. These types of sensors are referred to as analog sensors. Since computers recognize only digital signals (characterized by on/off levels), hardware is required to translate sensor signals. The PC data acquisition hardware may be in the form of an internal board that connects directly to the PC system bus (figure 2), or it may be external to the PC and equipped with communication hardware that interfaces with the PC serial or parallel ports, or through internal bus cards that provide alternate external interface hardware (figure 3). Enclosures, cables, power supply and conditioners, and signal conditioning circuitry may also be required to interface with the sensor. P. 683

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