Extensive underground utilities are located all over Hong Kong, supporting the everyday life of the general public round-the-clock. The complexity of underground drainage system has, however, posed numerous challenges on maintenance and repair. In view of this, the Electrical and Mechanical Services Department (EMSD) and the Department of Electronic Engineering of the Chinese University of Hong Kong (CUHK) have jointly developed a new wireless communication solution for underground utilities in the manholes. The EMSD and the CUHK have been working closely with the Drainage Services Department and Water Supplies Department to overcome limitations and to embrace challenges with innovative technologies in order to enhance the monitoring and maintenance of the utilities. We also successfully patented the solution by the end of last year.
Generally speaking, it is not an easy task to establish a wireless communication system for devices deployed in an underground environment, as Radio Frequency (RF) signals have to penetrate heavy and thick manhole covers to transmit data to nearby base stations. The data would then be sent to operators' devices through wireless network for analysis. One of the major challenges for applying wireless devices to manage underground utilities is that RF signals would be weakened when blocked by manhole covers. Another major challenge is the large power consumption of traditional wireless devices, which results in frequent manual replacement of batteries, and hence increased management cost.
Co-ordinated by the EMSD, this innovative solution works on improving the communication channel by seeking a synergy of complementing the Quadrifilar Helix Antenna (QHA) (antenna generally used for satellite communications) developed by the CUHK with the advantages of the Government-Wide Internet of Things Network (GWIN) to solve the problem of signal blockage of manhole covers. It helps increase the effectiveness of radio communication in underground environment, and reduce the power consumption of wireless devices and the frequency of batteries replacement. With numerous laboratory adjustments and on-site tests, the new device has achieved stronger antenna effectiveness and relatively higher signal reception and transmission success rate.
The innovative solution is designed to benefit various underground utilities and it can be implemented at flooding blackspots of stormwater drainage systems and freshwater piping systems. The newly developed device is capable of assisting data collection and providing near real-time monitoring of condition of utilities, ensuring their normal operation and checking leaks in the pipes, etc. With such functions, a long-term near real-time monitoring is achieved, protecting the underground utilities of the smart city.