EuroWire September 2016

Technical article

A New Flat Indoor/Outdoor Drop Cable for FTTH Applications By Qin Yu, Fei Qian, Liming Chen, Qingqing Qi, Shiying Wang, Huiping Shi, Cheng Liu FiberHome Telecommunication Technologies Co Ltd

Abstract This paper presents a new flat indoor/ outdoor drop cable for FTTH application. The flat cable is all dielectric and with an oblong cross section, and could be applied to harsh environments with large bending stress, lateral pressure or wind load. Therefore, the flat cable is conducive to the realisation of large-span aerial installation and is particularly suitable for the indoor and outdoor drop application in the FTTH access network. In this paper, three different combinations of materials are explored to verify the processing performance and product properties of the cable. That is, different combinations of sub-unit material and outer sheath material. Eventually, it was found that the two kinds of the cable structure could totally satisfy the users’ requirements and have excellent transmission, mechanical and flame retardant characteristics, and could apply in the FTTH applications. 1 Introduction In order to realise the tri-networks integration as soon as possible, operators in China continue to promote large-scale FTTH network construction. A FTTH network can not only provide higher bandwidth, but also improve the anti-interference performance of the access network and integrated access capacity of service. To meet the different demands of users, there are many types of FTTH optical cable for unceasing requirements from users, such as different demands of construction

Outer sheath Sub-unit sheath

Tight buffered fibre FRP

Strength member

▲ ▲ Picture 1 : The cross section of the flat cable

costs, convenience and rapid cable laying, and the reliability of the optical fibre communication lines. Therefore, it is very important to choose an appropriate cable for different drop applications.

• Smaller size and can save laying space • Easy to branch and save construction time and money • Easy to manufacture and can keep the continuity and consistency of processing • Easy to install, maintain and replace

2 Common drop cables

3 Structure of the flat cable

In general, drop cables are small count fibres with special designs, and most drop cables are of self-supported structure with tight buffer fibres. The most common shapes of drop cables are figure-8 bow-type cable, round cable, or some other special drop cables, such as low friction bow-type cable and invisible micro cable and so on. In the present drop applications, the figure-8 bow-type cable and round cable were used widely. As new drop cables, low friction bow-type cable and invisible micro cable were gradually accepted by more and more users. Although drop cables become ever more diverse, different kinds of drop cables usually have the following characteristics: • Diversified and rational structure, could satisfy the users’ special requirements

3.1 General structure of the flat cable The flat cable developed for this paper was to satisfy the customers’ requirements for indoor and outdoor drop applications with both aerial and duct construction. The cable should have good directional bending properties and excellent ability to resist lateral pressure. Moreover, the flat cable with oblong sectional profile should effectively reduce the destructiveness induced by wind load, and be adaptable to various harsh construction conditions and a complex environment. Given the specific application environment, the flat cable was designed with an outer sheath, sub-unit sheath, tight buffered fibre, FRP and strength member. See Picture 1 .

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September 2016