Abstract

The goal of the Carthage Atmospheric Electricity Research and Education Network (CAERENet) is the study of Earth's electrical environment through the creation of a network of electric field meters (field mills) to be placed at local schools.  Since field mills must be outdoors to collect data, work was done this summer to enable the remote operation of the mill and transmission of data to a mini-computer located indoors for storage and visualization.  The mini-computer was connected to the field mill instrument by various digital input/output pins and by writing a protocol to organize robust long-distance communication.  The protocol is based upon the Serial Peripheral Interface (SPI) with an extra clock line to ensure organized communication despite the long wires required and the different internal clock speeds of the two devices.  Tests of the protocol demonstrate robust low-bandwidth (10 kilobaud) communication over 100-foot distances, limited primarily by the speed of the field mill microcontroller.  The development of a data transfer system and user-interface for the electric field mill will support CAERENet's goals by providing real-time data for analysis in the classroom and for transfer over the internet for large-scale network data analysis.