To capture rare events with high accuracy demands extraordinary design, material and software requirements. High sensitive sensors and electronics exposed to the elements have to take thousands of samples per second day by day, year by year.
The huge amount of data can not be transported nor stored. And even if, it would be of no use. Hence we developed "smart sensors" that "learn to see" abnormalities. During inter-event periods the data is statistically compressed to reduce storage and transport. On abnormalities the devices store all high frequency data, divides the complete data set into transportable packages and sends them to the data-warehouse.
As we all know toplevel achievements comes at great costs. Modern readily available electronics like the Arduino and Raspberry Pi can reduce these costs. The image shows a field data acquisition system with a monitored stabilized UPS, a 3G modem based on the PI2 and two in house design multi-channel high resolution 4-20mA PI-shields to monitor 32 channels simultaneously.
All wiring is designed to minimize influences from electromagnetic disturbances. Special care was taken to prevent floating zero differential. The 4-20mA signal was chosen for its capabilities of long distance wiring necessary in field operations, excellent stability and the availability of a wide range of sensors.
A special note deserves the solar power supply. This was designed to guarantee the delivery of a constant (< 1% fluctuation!) power supply during the lowest solar elevation periods (December/January) with maximum cloud coverage during 10 days uninterrupted.
This installation delivers absolute top DA performance at a fraction of the costs of comparable field systems today.