根據對金屬接觸式水溫水位傳感器結垢成因的分析，提出在傳感器兩端注入對稱交流信號抑制水垢形成的方法。介紹了一種基于ATmega48 低成本、高性能的太陽能熱水器
防垢水溫水位測控儀的設計。通過對測量噪聲的分析，建立“白噪聲+工頻干擾”的噪聲模型。 針對這種噪聲，運用過采樣和求均值的方法提高ADC 有效分辨率和改善信噪比，并給出一 種抑制工頻干擾的方法。
關鍵詞：太陽能熱水器；水垢；噪聲；過采樣；水溫水位
Abstract：In the first place, according to analyzing the causes of formation scale of metal
contiguous water temperature and level sensor that a method presented by adopting symmetrical AC signal in this paper. This paper introduces a prevent scale design circuit of water temperature and level of solar energy heater based on ATmega48, which is of lower cost and higher performance. Another innovative consideration here is, what’s more, that system noises can be modeled white noise & power line interference from the analysis of noises and interferences in the system. Last but not least, this paper describes utilizing oversampling and averaging to increase the resolution and SNR of analog-to-digital conversions, and adopting a special sampling to suppress power line interference, as far as the noises are concerned.
Key Words：solar energy water heater; scale; noise; oversampling; water temperature and level