A detection system for measuring the size and number of water drops via the change of capacitance of a parallel plate capacitor is presented in this thesis. A voltage divider is formed with two capacitors connected in series, where one of the capacitors is being exposed to water drops and the other one is used as a reference. When a drop of water falls between the plates of the capacitor, the total permittivity of the capacitor changes. The permittivity of water is much higher than the permittivity of air, so the rise in capacitance changes the voltage divider ratio. The obtained voltage is proportional to the size of the water drops which were characterized with numerous measurements. The volume of water drops can be summed in a specific time frame and therefore the water flow can be calculated.
The introductory chapters of the thesis present the characteristics of precipitation, together with a brief history of development, and an overview of existing precipitation measuring devices. The following is an explanation of the theoretical background of the operation of the designed measuring system, a description of the process of developing an analog circuit and an explanation of the operation of individual parts of the system. Then we have a description of the parts of the program that include detection algorithms and water droplet processing. Finally, a description of measurements and analysis of the obtained results follows.
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