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Large-scale Real-time Water Quality Monitoring Using Satellite-Linked Sensors
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Project Title: Satellite Linked Hydrologic Sensor Platforms Networked for Large-Scale,Real Time Water Quality Monitoring Throughout the USA
Research Locations:Chesapeake Bay, VA
Last Update: January 15, 2004
Although a variety of data transmission methods and data retrieval options exist, obtaining large-scale, real-time monitoring information is limited by several factors such as high cost, variable data throughput rates, reliability issues, and infrastructure problems. Currently, the National Estuarine Research Reserves utilize YSI multi-parameter sondes to collect water quality data in the field. Sondes are often located in remote or distant locations, where cellular or VHF transmission may not work well due to line of sight or cellular signal problems. This project is developing a low-cost satellite transmitter device capable of telemetering real-time water quality data directly to end users through a seamless internet web site.
The Remote Access Sensor Link (RASL) Technology
Satellite technology has been available for several years, however, high costs and satellite accessibility issues have made it impractical for most monitoring programs to use. Hardware and airtime were prohibitively expensive, and orbiting satellites were not always available at the moment data was ready to be transmitted. The new Remote Access Sensor Link (RASL) terminal incorporates a Globalstar transmitter, which accesses a voice communications system consisting of over 48 Low Earth Orbiting (LEO) satellites. This large-scale network allows for lower costs and guarantees that a satellite will be in view at all times.
How it works
The RASL data communications system includes a satellite transmitter combined with a sensor interface and data logger. The device easily connects to a YSI sonde and provides a communication link between the sensor, a satellite and the research laboratory or ground station. Data is downloaded from the YSI instrument and logged in a hard drive, then re-packaged so that it can be read by a satellite. In a matter of seconds the information is transmitted from the satellite to the ground station where it can be viewed using a web browser.
Latest results
A demonstration carried out in the Chesapeake Bay, VA NERR in the Fall of 2003 proved highly successful. Investigators are now looking to finalize the internet data delivery portal, where data can be viewed
and downloaded from the internet as an Excel file, or sent to a user’s FTP site or web server.
Rapid, reliable delivery of information
Each data broadcast is sent three times in quick succession, ensuring that at least one transmission to a satellite is received. Data can be telemetered as frequently as necessary, at any time of the day. And, because it is also logged, no data is lost if transmissions are not successful.
Cost-Effective Technology
The new device will cost approximately $1000. Satellite time, normally the greatest expense, will amount to $140 per unit, per month for hourly recordings. Because the RASL device is programmable, the user is able to choose the frequency of data transmission; Fewer transmissions means lower cost.
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Project Coordinator
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Dr. M. Blake Henke (410) 961-6692 |
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Start -End Date:
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09/01/2002 - 09/01/2004
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NERR Reserve(s):
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Chesapeake Bay, VA
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For more information: |
Dolores Jalbert Leonard |