Wearable Measurement Method for Voltage to Ground of Conducted Noise on Unshielded Cables

Data communication systems that use metal cables as transmission lines such as Asymmetric Digital Subscriber Line (ADSL) are used all over the world because they make it possible to develop broadband services using existing telephone lines. On the other hand, these services are known to be affected by conducted noise. When communication problems occur that are possibly generated by conducted noise, technicians carry out the measurement of the conducted noise using measurement equipment such as the oscilloscope, and locate and remove the noise source or select and apply the appropriate noise filter. Therefore the development of a simpler measurement method is desirable in order to reduce the burden on the technicians. We propose a method to measure the voltage to ground of conducted noise propagating on a communication line with a wearable measurement instrument using the human body as a probe. The proposed wearable measurement instrument is composed of a device for deriving the conversion factor, which changes in relation to the ground capacitance at the measurement location, and a device for measuring voltage, and each component is mounted in a shoe, so the complete instrument becomes a pair of shoes. The measurement is carried out when a technician wearing the measuring instrument grasps an unshielded cable in which conducted noise is propagating. In our experiment, the conversion factor of the developed measurement instrument was obtained, and the voltage to ground of sinusoidal waves from 1 kHz to 10 MHz was measured in a shielded room, and it was shown that measurement was possible with an error of less than 1 dB. This result demonstrates the possibility of the proposed method for measuring the voltage to ground of conducted noise using a wearable measurement instrument.