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.

This paper presents a wireless burst modulation/ demodulation method for narrowband ubiquitous communication systems. This method especially suits those systems, whose traffic is especially dominated by short frame bursts. The proposed modulation method provides a preamble-less frame structure with training symbols, which improves both transmission efficiency and burst synchronization performance. Moreover, the proposed demodulation method achieves superior burst synchronization performance in low carrier-to-noise power ratio (CNR) environments by applying a synchronization method that includes symbol timing recovery, slot synchronization, carrier frequency correction and channel tracking. In addition, this paper presents the result of experiments on hardware prototypes of the proposed modulator and demodulator. The basic operation and practical performance of the proposed method is confirmed through testbed studies.