The US Weather Service presently uses a "tipping bucket" rain gauge for measuring rain accumulation. This device is sensitive to wind and motion (as on buoys), cannot measure rain rate, and requires frequent maintenance, because of moving parts. An alternative device is being proposed, which incorporates a rigid, resonant tube, closed at the top by an electro-acoustic transducer, and at the bottom by the rain level. Acoustically inert ports will allow water to enter the bottom and air to vent at the top. The tube will resonate at a frequency that varies inversely with the distance from the top determined. The tube resonance can be determined, electronically, from the variation in the impedance of the transducer with frequency. The process would be controlled by a microprocessor which would also perform calibration status verification, and interface with external equipment. In addition, the water reservoir would incorporated a calibrated, continually open, drain orifice, which would eliminate the need for a mechanical drain. The effect of the orifice on the measurement could accurately be accounted for in the processing.Commercial Applications:This device has applications for rainfall measurements for amateur weather enthusiasts, and to an commercial products where it is necessary to measure the height of a liquid, with the high reliability, resulting from no moving parts. Examples would be automotive and marine fuel tanks, and underground gasoline and oil storage.
