Datalogger (Datalogger with Dedicated Spectrum Analyzer for Vibrating Wire Sensor Signals) with dedicated spectrum analyzer software designed to collect signal measurements of from vibrating wire sensors.
Datalogger is a microprocessor system, which steers the stimulation of vibrating wire sensor with an impulse signal, as well as control collecting, processing and archiving of pressure measurements on the basis of signals generated by vibrating wire sensors such as: EPW3 or EEPW3 of GLOETZL Co.
Vibrating wire sensors are used in geotechnical measurements to observe orogen or mass rock processes directly in a place, where they originated. These sensors are employed in deep-seated displacements (inclinometers) measurements and in the measurements of pressure (bore-hole probes). This is a basis to verify project assumptions and to undertake activities due to (in order to) protect or restrict negative effects of threats occurrence in a process of exploitation of deposits with a strip mining method, the use of hydro-technical objects or other objects situated in places, where threats difficult to predict occur due to specific geological structure.
Pressure Measurements in orogen are usually effectuated by three sensor bore-hole probes, which are properly oriented toward vertical axis. A single sensor is basically constituted by rectangle shaped hydraulic cushion where the pressure changes are measured in a range up to 600 bars. A change of load of the hydraulic cushion connected with an electric vibrating wire sensor, modify the string tension as well as it’s vibration frequency. Datalogger periodically generates an impulse signal stimulating the string and records the measurement of respond signal. Afterwards the software dedicated for spectrum analysis of the string signal determinates it’s frequency.
Datalogger VWSS controls the stimulation of vibrating wire sensor with 24V impulse signal and determines a frequency of the string vibrations within 1800 to 3600Hz, with an accuracy of measurement valued to 0.1Hz. This accuracy is received by means of dedicated algorithms of spectrum analysis. Moreover, microprocessor system measures a thermo-resistor resistance ranging from 1 to 10k with accuracy to 5 and gives values of temperatures in the range: -10 to +40C.
Datalogger microcontroller operates 8-input modules of analog transducers with a galvanized isolation, which enables the connection with 24 vibrating wire sensors. Measurements are stored in a buffer in a capacity of 8192 records from read-outs, presenting for each read-out a measurement date, frequency of the vibrations of the string and a temperature of the sensor. Microcontroller makes the communication link RS232 accessible, the link serves the protocol MODBUS RTU.