Explanation of the criteria for classification and numbering of components    C30.3.01
 (DEC 99)
Explanation of the dates on the component's description


1.   Purpose and objectives

     To collect and report automatically precipitation data using radio signals.

2.   Description

     The data reporting package is modularly designed, including tipping bucket mechanism, radio telemetry unit and power supply. Each tip of the bucket, usually measuring 1 mm of precipitation, causes transmission of a signal which identifies the station and gives the accumulated value. This 
information is decoded at the ALERT Base Station (see HOMS Component F00.3.05). The battery pack power supply and telemetry equipment are located in the base of a standpipe housing which is fixed to a concrete base. The tipping bucket and antenna assembly are located at the top of the standpipe cylinder (10 to 16 feet, 3 to 5 metres high).

3.   Input

     Precipitation. May also include any other environmental sensors, such as temperature, wind, relative humidity, or river stage.

4.   Output

     Digital or analogue signal transmitted on a specific radio frequency with four-digit station identifier and four-digit accumulated rainfall value. The signals are received by component F00.3.05 "ALERT Data Collection Substation".

5.   Operational requirements and restrictions

     Two people should be trained in installation and maintenance procedures. Approximately one week of training is needed.

     Installation requires two people. Equipment is needed to dig the hole for the concrete base in addition to the ingredients for mixing concrete.

It is desirable to have some electronic testing equipment at the field site such as remote station tester, wattmeter and voltage meter.

     Installation requires approximately four hours. Concrete base should be located below the depth at which the soil freezes in a keyhole shape to prevent the base from being loosened by freezing and thawing.

     Battery-pack power supply should be recharged or replaced annually or after 20,000 transmissions, whichever comes first. Batteries may be supplemented by the use of solar panels, or by A/C power if available.

     Extreme care in gauge siting is needed to ensure clear radio transmission pathways. Signal strength tests should be performed prior to installation under various seasonal and meteorological conditions. A relay tower with repeater may be necessary.  

6.   Form of presentation

     Technical description of the rain gauge and transmitter.

7.   Operational experience

     Has been used successfully worldwide, with the most extensive use in the U.S.A. Use has been particularly advantageous for basins where time to flood peak is less than 24 hours.

8.    Originator and technical support

      The technology was originally developed in co-operation with the Sacramento (USA) River Forecast Center, U.S. National Weather Service. A list of vendors providing technical support can be obtained from links on the home page of the ALERT Users Group. The address of this home page is

9.    Availability

      From the HOMS National Reference Centre for U.S.A.

10.   Conditions on use

      Descriptive material free. The gauge is for sale through commercial vendors, as a package including all elements for operation of the self-contained station.


(First entered: 26 JUL 83

Last updated: JUL 99)