United States Department of Agriculture
Natural Resources Conservation Service
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National Water and Climate Center

Water and Climate Program
Products and Services Briefing Book

Data Acquisition Technology

The National Water and Climate Center (NWCC) has developed efficient and highly effective technology to provide the data needed for water supply, climate, analysis, and conservation planning. NWCC acquires additional data sets that are needed from other networks and designs local data networks and sophisticated national networks. NWCC operates a variety of networks that use different data acquisition technology. We offer our expertise to others through documentation, training, partnership, on-site assistance, and participation in professional forums. Briefly, some of the types of data acquisition technology that are currently established are:

[Illustrates Meteor Burst Communication Technology]

Meteor Burst Communication Technology
Meteor burst communication was discovered by the military in the 1950's. NRCS implemented this technology and developed SNOTEL in 1975. Meteor burst communication uses the billions of sand sized particles (1 gram or larger) that burn up in the 50 to 80 mile high region of the atmosphere to relay radio signals back to the earth. This technique allows communication to take place between remote sites and a master station up to 1200 miles away. At the master station, the remote site data is checked for completeness. If so, an acknowledgment message, returning over the same path, tells the remote site not to transmit again during this polling period. The entire process takes place in less than a tenth of a second. Meteor burst communication has proven to be extremely reliable. From the master stations, the data are sent via telephone line to the NWCC Central Computer Facility.

Cellular Phone System
The NWCC designed and currently operates two real-time data acquisition systems that utilize cellular phone technology for data transfer from remote locations. The NWCC computer center automatically dials sites in Maryland and St. John Island, U.S. Virgin Islands, and transfers data to the NWCC Central Computer Facility.

Data Logger
New developments in data logging technology facilitate the development of small, locally operated, and inexpensive remote resource data acquisition systems. These systems can be managed directly by field offices. NWCC assists in the operation of several small systems that collect data from a variety of sensors and store the data on-site for later downloading to a portable computer database for analysis and product delivery.

Electronics Maintenance Facility
The NWCC operates a SNOTEL electronics maintenance facility that maintains a fully functional complement of modular SNOTEL components that can be sent overnight, worldwide if a component fails. The facility also repairs data acquisition systems sent in from the field, designs custom interface boards, tests sensors, keeps abreast of latest technology, and provides answers to technical questions related to data acquisition technology.