Autonomous buoyed environmental system

The engineering development path of the Autonomous Buoyed Environmental Sensor (ABES) system is presented. Emphasis is on the placement of a micropower 8-bit microcontroller at each sensor, thereby enabling control, addressing, and data telemetry over a single conductor and allowing 12-bit digitization at each sensor. ABES is a lightweight, reconfigurable, integrated oceanographic measurement system intended to provide oceanographers with the opportunity to accomplish increased spatial sampling of the shallow-water ocean environment due to its ease of use and low cost compared to more traditional methods, albeit with slightly degraded accuracy and resolution. The instrument is a sensor string connected to a cylindrical electronics canister. The prototype sensor string contains one electromagnetic current meter, 3 tilt sensors, 3 magnetoresistive compasses, and 10 conductivity, temperature and depth sensors, the latter developed in conjunction with Ocean Sensors, Inc. These sensors are distributed along a 40-m cable. A system controller GPS receiver, and spread-spectrum radio are housed in the 1-m long electronics canister. Together, these components weigh 10 kg in air and occupy a volume of 5 l