Implementation of Maintenance System Based on Bluetooth Low Energy for Hermetic Inline Amplifiers in CATV Networks

Katsuhiro Naito, Kenta Nakanishi, Kazuo Mori, Hideo Kobayashi

Cable television (CATV) systems generally consist of a headend, trunk cables, distribution cables in the neighborhood, drop cables to a home and in-house wiring, and terminal equipment. Coaxial cables bring a CATV signal to customer premises through a service drop, an overhead or underground cable. Hermetic inline amplifiers are used to amplify the attenuated CATV signal due to propagation loss or splitting the coaxial cable. They are usually installed on utility poles. Therefore, maintenance methods for inline amplifiers on utility poles are important issues in CATV operations. This paper proposes a new maintenance system for inline amplifiers in CATV systems, and develops a prototype implementation. The proposed system consists of an amplifier gain analyser to measure amplification performance of inline amplifiers, a special smartphone application, and a cloud server. The proposed amplifier gain analyser is composed of three functions: a generation of high frequency signals for testing, measurement of the test signal gain, and wireless communication based on Bluetooth Low Energy (BLE). We develop a signal generation circuit for a test signal and a smoothing circuit for converting the high frequency test signals into DC signals. The amplifier gain analyser can evaluate an amplifier gain by comparing an input test signal from the signal generation circuit and an output test signal from an inline amplifier. The measurement function uses Nordic nRF51822, which is a System on Chip (SoC) for BLE because Nordic nRF51822 has some AD converter ports for evaluating the DC signals. The smartphone application employs BLE communication function to collect the measured amplifier gain from the amplifier gain analyser. Therefore, we developed a special data collection application for iOS. The data collection application has a central function of BLE, and can find a target peripheral device that is the amplifier gain analyser in this paper. Therefore, technicians of CATV systems can easily check the operational status of inline amplifiers on utility poles. Additionally, the smartphone application can upload the measured information to a cloud storage server. We employ Google App Engine and use Cloud Datastore to implement the cloud storage service. Therefore, our storage service has flexibility for various kinds of information.

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