Shinji Tsuzuki

Characteristics of Power-Line Channels in Cargo Ships

The broadband PLC in cargo ships is a long-awaited technology. However the characteristics of power-line channels in the cargo ships have not been studied yet. The most unique point of the channels is that power-line cables used in most Asian cargo ships are shielded. In order to characterize the channel and investigate a suitable PLC system to the cargo ships, some parameters were measured in three typical ships. The parameters were the transfer functions (LCTR, LTR and TTR), LCL and stationary noise spectrum. From these measurements, (1) the required dynamic range of receivers, (2) average attenuation at distribution boards, (3) phase coupling loss and (4) average LCL values were derived in this paper. Since the cables are shielded and the hull provides the good ground, the usage of the common-mode transmission in addition to the conventional differential-mode, which is referred to as a dual-mode transmission system, is also proposed. Therefore the measured parameters above were included the common-mode and mode-conversion properties. As the evidence to support our proposal, some results in which the LCTR values were superior to the TTR values are shown.

Channel characteristic comparison of armored shipboard cable and unarmored one

Power-line communication (PLC) based local area networks (LAN) in ships are one of the promising applications of the PLC technology. There are two types of ships from the viewpoint of the cable structure. One is all the power- line cables are armored, and another type is partly unarmored cables are used. For example, all the cables in cargo ships whose characteristics we measured at last year, were armored, although the cables in a training ship shown in this paper are unarmored partly. In this paper, the channel characteristic which the cable structure affects has been discussed by comparing the two types of ships. It has been concluded that if the unarmored cable is used in a ship, the common-mode transmission will be more useful than the conventional differential-mode transmission, although the countermeasure against unintentional radiation will be needed at the same time. If all the cables are armored in a ship, the radiation problem will not occur, although a kind of adaptive transmission-mode selection technique will be needed to improve the channel capacity of the conventional differential- mode transmission system.

Feasibility study of ubiquitous sensor networks by inductively coupled PLC over PV power systems

Simple and low-cost PLC will be required to play a role in the Internet-of-Things (IoT) market such as ubiquitous wireless sensor networks. From the viewpoints of temporal connectivity and obtaining high SNR and stable channels, inductive coupling techniques for the kHz band PLC have been proposed in this paper. The results of three feasibility studies using a photovoltaic power system installed in our laboratory have been described. First, an inductive coupler is applied to the DC powerline channel, because it forms a low impedance loop circuit. It was proved that the DC power-line provided a high SNR channel, so that the simple modulation technique was enough to realize the ubiquitous PLC networks. The second topic is the contactless power supply using the same ferrite core as the PLC coupler. It has been shown that the proposed circuit could supply power of 35mW at the maximum to a wireless sensor node. The third topic is an application of the 1-wire PLC system to aerial cables. A suitable coupling method has been proposed to provide a low signal attenuation channel. The noise characteristic peculiar to photovoltaic (PV) power-line is also pointed out, that is the amount of noise on a sunny day with cloud occasionally exceeded that on a cloudless sunny day.

Dual mode transmission PLC system with an EMC considered algorithm

A dual-mode transmission system which utilizes the differential and common modes has been proposed. To improve the channel capacity, a simple diversity, which selected the better transmission mode at a client PC side, was examined at laboratory rooms in a building. It was found that the amount of throughput improvement was 45% compared with the conventional single mode transmission of differential-mode. To overcome the unintentional radiation problem caused by the common-mode transmission, an EMC considered algorithm referred to as a power control algorithm which was adaptive to the electromagnetic environment (AEE) was applied to the proposed system. It has been concluded that relatively small areas such as in a house, an office floor in a building and so on, would be the suitable place of the proposed system.

An adaptive power control method to electromagnetic environment for PLC in cargo ships

Power-Line Communication (PLC) based Local Area Networks (LAN) in ships are one of the promising applications of the PLC technology. However, the unintentional-radiation is the serious problem for ship applications because the PLC system must coexist with the emergency communication system and shortwave broadcasting services. In this paper, a power control method of PLC modems depending on the radiation strength is proposed and examined in a training ship. It is proposed to use an antenna for shortwave radios and a wideband receiver (WBR) to measure the radiation strength. It is shown that the sensitivity of the WBR is 17dB better than that of a spectrum analyzer. And by using the antenna, the WBR can be set up at any cabin in ship to measure the radiation strength. The proposed power-control algorithm consists of two modes, silent and power-control modes. After the environmental noise level is measured in the silent mode, the power level of PLC modems which cause the radiation is lowered to be the same level as the environmental noise level. If modems do not cause the radiation, their power level is raised as much as possible to guarantee the maximum possible throughput under the EMC regulation. By executing the silent mode occasionally, the controlled power level is adapted to the environmental noise level.

Characteristics of 440V power-line channels in container ships

Control and monitoring is a promising application of power-line communications (PLC) in cargo-carrying ships. The container ship studied in this paper is a type of cargo-carrying ships. The reefer containers on the container ship have been monitored by using PLC over the three-phase 440V line. Since not only reefer containers but also a lot of equipment are connected to the three-phase 440V electric power-line, the obtained speed and quality of the PLC system have been so poor that improvement had been required. To improve the performance, the introduction of the wideband PLC technology is considered in this paper because the conventional PLC system is based on the narrowband PLC technology. There are few reports which describe the channel characteristics of cargo-carrying ships. Although the authors had been measuring the characteristics of 100V lines in the ships since 2007, the characteristics of 440V lines had not measured as yet. In this paper, the measurement results of the transmission characteristics in three-phase 440V electric power-lines of the container ships are explained and modeled. Two transmission modes, differential and common, were examined in the measurement. The results show that it will be possible to perform stable and high -speed PLC systems over long distances using the 3 phase 440V power-line of cargo ships if the differential transmission mode will be used.

High-Speed Power-Line Communication and Its Application to a Localization System

This paper overviews the high-speed power-line communication (PLC) technology, and the related standardization and regulatory activities are described. PLC modems of 200 Mbps class become a practical use stage in the West, and the standardization activity is active now. The discussion for deregulation is being continued in also Japan, and regulation values have been proposed. Another topic in this paper is a sensor network application of PLC, which is an indoor fine-grained localization system by acoustic Direct-Sequence Code Division Multiplexed (DS-CDM) signals. The obtained average accuracy of the localization in a 4 m 2 plane was 1 cm if there was no obstacle. To realize the localization system, some novel ideas, such as PLC speakers, a synchronization method based on the zero-crossing timing of the mains frequency, and integrated wired/wireless PLC, are introduced.

A feasibility study of 1Gbps PLC system assuming a high-balanced DC power-line channel

To realize an eco-house, a new direct current (DC) distribution system has received widespread attention. This paper has proposed countermeasures to fundamental problems which make difficult to achieve a high-speed PLC over the existing alternating current (AC) systems. To reduce the signal attenuation of the conventional low-voltage (LV) power-line cables made from vinyl insulator, it is recommended to use cables made from polyethylene insulator. It has been also recommended not to use the single pole and 3-way switches supposed to be cut into the hot conductor, and hand-made joint boxes in order to make the electrical balance of the channel high. To prove these proposals, a DC power-line system of 1.5kW capacity was built and the throughput was measured. The proposed simultaneous dual-mode system performed 1.9 times better throughput at maximum comparing with the conventional single-mode system. From these observations, a scenario for a 1Gbps Personal Area Network (PAN) over the new DC power-line channels is proposed.

Power-line channel modeling for common-mode signal transmission/suppression

The common-mode signal transmission and suppression are attractive from the viewpoints of the channel-capacity improvement and adaptive cancellation of the unwanted radiation from the power-line. To study this transmission and suppression, a channel modeling method based on the transmission-matrix theory is proposed in this paper. And the proposed modeling accuracy is evaluated by using an LCL probe, which the authors had developed. As an application example of the proposed model, the channel capacity depending on the electrical unbalance of power-line channels is approximated for the common-mode signal transmission.

Radiation detection and mode selection for a cognitive PLC system

To improve the throughput performance of HF-PLC systems, a dual-mode transmission system, which utilizes the mode diversity of differential and common modes, has been studied by the authors. However, the system which uses the common-mode has a risk to cause the unintentional radiation problem. To solve the problem, an Adaptive power control method to the Electromagnetic Environment, which is called AEE, has been proposed. The radiation detection was achieved by receiving emitted PLC signals at affected (or concerned) devices. In this paper, a new detection method and a new mode-selection method have been proposed, and it is shown that their preliminary results are attractive from the viewpoint of usefulness.