PORTABLE WIDEBAND MICROSEISMIC DATA ACQUISITION SYSTEM
Microseismic monitoring has gained importance ever since a correlation was established between earthquakes and intensive mining operations at various mine sites across the world. A microseismic network is in place at the Cory, Saskatchewan, mine site to record vibrations from minor tremors and to analyse the data to locate zones of impending faults. Precise fault location demands greater accuracy and resolution of recorded data - both of which depend on transducer characteristics. Different transducers can be designed depending on the parameters (displacement, velocity or acceleration) that they sense, the sensing element used and the placement of the sensing element in the transducer. Currently, mass spring transducers that sense velocity are the most common transducers. It is anticipated that, in future, new transducers will be developed for microseismic monitoring applications. Before deploying these sensors in microseismic networks, it is important to test them and validate their performance. The primary focus of this research was to develop a portable wideband data acquisition system that can be used to acquire data from newly developed transducers and compare the recorded waveforms with that obtained from transducers already in use. The data acquistion system developed in this research has an antialiasing filter with a cut-off frequency at 2485Hz. The AID converter has a default sampling 2500 samples per second. The developed wideband data acquisition system can be assembled and carried in a case and installed at site. The system can be remotely accessed and configured and allows for easy offloading of data to a soft media for futher analysis with other software packages. This system is not Intended for online analysis but only to acquire data and process it into a form readily readable by other analysis packages. The developed system was used to acquire test data using a geophone and a piezoelectric accelerometer developed by Dr. Brian Daku. The transducer output was read simultaneoulsy from the data acquisition system and an indicating instrument. The response curves show a close match between. these values over the selected frequency range, thus establishing software integrity. This thesis describes the design procedure and features of the portable wideband microseismic data acquisition system, the experimental setup and benchmarks tests conducted and an intepretation of the results obtained.