Telemetry Solution Sends Rainfall Intensity Data Online

Frog RX Rain Gauge Data Logger Sends Data over GSM/GPRS

CHESTERLAND OH — CAS DataLoggers has just provided the hydrometric monitoring solution for a meteorologist manning a weather station measuring local rainfall intensity over the summer. To get more accurate rainfall data for flood warnings and weather predictions he needed an environmental datalogger to connect to his smart SDI-12 output tipping bucket raingauges. Previously he had been looking at a combination datalogger and sensor but that product lacked a way to remotely send data directly to his desktop.

CAS DataLoggers supplied the weather station with two Isodaq Frog RX GSM/GPRS Data Loggers as a low-cost remote monitoring solution. The Isodaq Frog RX model is a rugged telemetry data logger sealed to IP68 rating for solid protection from the environment and able to withstand temporary submersion. Designed for quick deployment at a low cost, each rain fall logger has standard inputs including a digital event counter. Using the Frog's optional SDI-12 compatible multi-channel expansion port, the station's technician connected each logger to a smart tipping bucket raingauge sensor, with Channel 1 of each device recording 0.2 mm tip events.

Currently the Frog dataloggers have begun recording data at two remote rural sites where each device has been installed into an external plastic meter box enclosure. Through the connected smart sensors, the Frogs log the total amount of rainfall during the season to determine the local rainfall intensity in their area, given in millimeters per hour (mm/h). Now when the specified amount of precipitation falls in a given hour, it tips the rain gauge lever, spilling into the bucket and actuating a switch that electrically signals the Frog datalogger to record the data. The station's smart sensors give them data on accumulated rainfall oven the given period as well as total accumulation and intensity level.

Equipped with external antennas, the Frogs simultaneously transmit this hydrometric data directly to the meteorogist's office via their GPRS communications. All the data is accessible online using Isodaq's telemetry server, and the Frogs also download their data to PC once a week. After he receives the data, the meteorologist can apply a correction algorithm to adjust the data for periods of extreme rainfall.

Each logger's internal memory holds over 29,000 16-bit readings, overwriting the oldest data when the storage capacity is full. This secure data storage in flash memory prevents data from being lost if the battery happens to fail, and the Frogs have a low-battery alarm to indicate if this happens. For extended operation the Frog's internal lithium battery pack is designed for quick and easy replacement in the field and only has to be replaced once a year assuming that the modem is on 24/7. If this project had required a longer battery life, the station could have opted for an external lead acid cell battery. This is very reliable when combined with low-cost GPRS 'always-on' protocols.

For this application the meteorologist has also specified alarm limits on rainfall intensity so that in times of extreme precipitation the Frogs will automatically send him an alarm message.

The Frogs also include free configuration software: Harvest for Windows is provided with all Isodaq dataloggers and is available in versions for both Windows (98, 2000, XP, Vista or 7) and Windows Mobile (3, 5 or 6). Harvest takes users through configuration & test for telemetry modems, setup of the logger and defining sample rates and alarms. If required for other applications, users can also activate a control output on alarm. Operators can export data to CSV or XML format files and graph data for all channels.

The Frog dataloggers are ideal solutions in this hydrometric application since the meteorologist has access to all the rainfall data online and the Frogs also download their data to his PC once a week. No one has to spend time driving out to the loggers for data collection or frequent battery changes, which keeps costs down along with their relatively low cost. Additionally the Frogs' automatic alarms allow the meteorologist to keep on top of heavy rainfall events while the loggers themselves give reliable operation in the worst weather.

For more information on our Isodaq Frog RX data loggers which automatically send your environmental and hydrologic data directly to desktop, or to find the ideal solution for other application-specific needs, contact a CAS Data Logger Applications Specialist at (800) 956-4437 or visit the website at

Contact Information:

CAS DataLoggers, Inc.

12628 Chillicothe Road

Chesterland, Ohio 44026

(440) 729-2570

(800) 956-4437

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