DESIGN AND IMPLEMENTATION OF A MULTIMEDIA ENVIRONMENT MONITORING SYSTEM

摘要

This paper mainly designs a multimedia environment monitoring system for Jiangmen Underground Neutrino Observatory (JUNO), a large scientific facility consisting of overwater and underwater parts. The underwater part relies on 20 000 20-inch photomultiplier tubes (PMTs) to detect neutrino signals. The proposed system is made up of three parts: an overwater unit, an underwater unit, and data servers. The overwater unit monitors the temperature, humidity, and air pressure of each experimental hall in the overwater part of the JUNO. This unit is composed of multiple smart monitoring nodes. Every node supports wireless communication, thanks to an STM32 Microcontroller unit (MCU), and a Raspberry Pi-based communication controller. The underwater unit monitors the temperature of the water pool in the underwater part of the JUNO, using Fibre Bragg grating (FBG) temperature sensors. These sensors at different monitoring points are connected in series through the optical fibre, with one end interfacing the channel interface of the FBG demodulator. The demodulator detects the central wavelength of each sensor, and converts it into the water temperature of the corresponding monitoring point. The data servers acquire the data monitored by the overwater and underwater units via the Transmission Control Protocol/Internet Protocol (TCP/IP) network. The monitoring system was tested in South China National Centre of Metrology (SCM), Guangdong Institute of Metrology. The results show that the overwater unit of our system controlled the temperature error below 0.5 degrees C, the humidity error below 3% RH, and the pressure error below 1mbar; the underwater unit controlled the temperature error below 0.2 degrees C. Therefore, the proposed system provides a reliable data source for studying the influence of environmental parameters on the performance of the electronics system.