This paper presents a water leakage monitoring system that gathers acoustic data of water pipes using wireless communication technology and identifies the sound of water leakage using machine leaning technology. To collect acoustic data effectively, this system combines three types of data-collection methods: drive-by, walk-by, and static. To design this system, it is important to ascertain the wireless communication distance that can be achieved with sensors installed in a basement. This paper also reports on radio propagation from underground manholes made from reinforced concrete and resin concrete in residential and commercial areas using the 920 MHz band. We reveal that it is possible to design a practical system that uses radio communication from underground sensors.
Expectations have been raised for a social infrastructure maintenance system that utilizes IoT/M2M technology. We are working to develop a water leakage detection system using wireless sensors set into the water pipes. However, radio propagation is restricted in the constrained underground environment of water pipes so how to collect the data and identify leaks is an issue. We propose a system that combines drive-by data collection and static data collection, in order to collect acoustic sensor data from a wide area effectively [1]. We also propose a random noise removal method by focusing on the constancy of the leak sound, in order to identify leaks accurately. We show the results of evaluating the effectiveness of the proposed system in tests and real fields.
To achieve low conversion-loss and high imagerejection performance in the wide band for up and down conversion, an SSB subharmonically pumped mixer using an inphase RF divider/combiner is proposed. The SSB mixer monolithic microwave integrated circuit (MMIC) is integrated in a small area of 1.8 2 1.3 mm 2 and shows good performance at 21.6 to 30.8 GHz.Index Terms-Image-rejection mixer, monolithic microwave integrated circuit (MMIC), quasi-lumped stub, subharmonically pumped mixer, wide-band mixer.
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