Studies on Loss Aging in Submarine Coaxial Cable During Storage

Attenuation loss change in submarine coaxial cables during 4 years of storage has been measured. Attenuation loss is shown to increase for one year after manufacturing. Then, loss is also shown to increase during summer (May to October) and to stay constant or to decrease during winter (November to April of the next year). This work concentrates on the causes and an estimation method of loss aging. The first part of the paper covers experimental results on the cable aging phenomenon. The second part discusses various factors affecting loss aging, and shows that fretting corrosion on the outer conductor tape will be a main factor. The third part describes an estimation method for and countermeasures to avoid loss aging during cable storage.     

Nonmetallic 1000-fiber cable

A nonmetallic high-fiber-count cable that contains fiber ribbons inserted tightly into slots and has tensile force applied to the central and slotted-rod unit strength members is described. The cable bending flexibility, tensile strain, and cable diameter, which are important for its economical and efficient construction, were theoretically and experimentally evaluated and an optimum combination of diameters for the strength members was obtained. Based on the results, a nonmetallic 1000-fiber cable was manufactured and its transmission, mechanical, and water-blocking performances were confirmed to be excellent     

Loop-network configuration and single-mode optical fiber cable technologies for subscriber network

This paper will discuss optical fiber cable distribution networks for accomodating the immediate introduction of optical subscriber networks. The concepts of cable distribution system design, the maintenance systems and the cables and jointing technology for supporting these systems will be discussed. The results of experiments using related technology will also be discussed.     

The telecommand system

The telecommand system plays an important role in the success of any satellite mission. This paper provides insights into the design, development and evolution of theAryabhata telecommand system. The paper includes detailed specifications and performance of both the ground and onboard segments of the telecommand system.     

An adaptive buffer control scheme for slotted ALOHA satellite channels

The behaviour of the slotted-ALOHA random access satellite channel wherein each user with a finite buffer changes the retransmission probability in accordance with the queue length is studied. The finite buffer of each user is divided into a number of strata and whenever the queue length moves from one stratum to the other, the retransmission probability is changed to reduce the average queueing delay. The analysis carried out in this paper reveals that significant reduction in the delay can be achieved by this technique employing only a few strata.     

Automatic Variable Field Chopper Control System for Electric Railcars

1) The principle of the automatic variable field (AVF) chopper control system, 2) analysis of field characteristics, the field intensity to the chopper-conduction ratio, 3) applying the AVF system to high voltage, large capacity, high frequency chopper equipment, and 4) test results on the Chiyoda Line of Teito Rapid Transit Authority are discussed.     

Low-loss plastic molded optical multifiber connector for ribbon-to-single fiber fan-out

This paper describes a newly developed low-loss demountable multifiber connector for ribbon-to-single optical fiber fan-out. The connector plugs contain special gathering parts that make a high-density arrangement for monocoated optical fibers. Using a multi-V-grooved mold, the optical fibers are accurately positioned and then a plastic formation process is adopted to form the plug. Plugs are precisely aligned by using two pins. An average connecting loss of 0.07 dB has been achieved in the stationary mode distribution with index matching. The change in connecting loss did not exceed ± 0.03 dB when the connector was subjected to heat cycles in a temperature range of-30-+60degC.     

Maximum measurable distances for a single-mode optical fiber fault locator using the stimulated Raman scattering (SRS) effect

Maximum measurable distances for a single-mode optical fiber fault locator using the stimulated Raman scattering effect were calculated. Calculations were carried out on the assumption that the light source is an Nd:YAG laser operating at 1.06 μm and the photodetector is a germanium avalanche photodiode (Ge-APD). The first to the seventh Stokes lights can be detected by the Ge-APD. Calculations show that a break can be measured in an up to 165 km long ultra-low-loss single-mode fiber.