Submarine Cable System Research Articles

Pulse Modulation and Signal Processing Circuits to Perform Precise Control and Monitoring Functions with High-Voltage Isolation

Pulse-position modulators are used for remote sensing of analog signals in a high-voltage constant-current dc power supply for a wideband submarine cable system. The pulse-position modulators translate the sensed analog signals into the time domain in the form of time delayed pulses. The transfer characteristics of the modulators are linearized and made insensitive to clock frequency and other sources of timing errors by use of a demodulator feedback circuit. The modulators are operated synchronously by a common clock. The clock also establishes a precisely quantized time frame which is useful in processing the modulator output signals. A variety of closed- and open-loop control functions, level monitoring functions, and both analog and digital metering functions are realized. Pulse transformers are used for dc isolation and common mode noise rejection.

Wide-Band Partial Discharge Detector

A wide-band peak voltage detector is presented, which is used for measuring partial discharges in submarine telecommunication cable systems. For high-voltage discharge detection of simple dielectric geometries or complete power filters, the wide-band detector is suitable for laboratory or factory use. A low-cost low-resolution amplitude-distribution analyzer can be assembled by combining several detectors for the special requirements of high-voltage dc testing, at a small fraction of the cost of a commercial distribution analyzer.

Reliability of semiconductor devices for submarine-cable systems

The Bell System initiated development of semiconductor devices for use in broad-band repeatered coaxial submarine-cable telephone systems in the early 1960's. Development of such devices has continued at varying levels of activity to this date. Now, over a decade later, more than five years of successful operational life have elapsed on the first installed system; one transatlantic system is in operation and several more of equal or greater length are in various stages of construction. Laboratory-like life validation tests have been conducted on all the devices for use in these systems, and up to seven years of history have elapsed on groups of 100 devices representative of the five varieties used in the first system. No failures have been observed either in service or in life validation tests, thereby confirming a FIT rate of better than five. Moreover, variables data for the representative samples aged for seven years indicate that the confirmed FIT rate may be extremely conservative. Silicon diodes aged below breakdown are more stable than the life-test system designed to evaluate their reliability. Silicon diodes aged in breakdown show a linear drift in leakage current which is so small that it is not detectable except with an ultrasensitive test system. Germanium transistors evaluated over this same period show that the change in current gain they exhibit will be substantially less than the goal established for them at the inception of development. Silicon transistors being developed for a new higher capacity system show promise of exceeding the stability of the more extensively evaluated germanium devices. These results have broader implications than their relevance to submarine-cable system performance since they indicate that the reliability which has long been considered to be inherent in semiconductor devices not only has been demonstrably achieved in quantitative terms but can be considered to be designable for future system applications.

A Precision Wide-Band Transmission Measuring System

The measuremnent of transmission characteristics with high precision is indispensable for testing and developing cables and repeaters in submarine cable systems. The precision wide-band transmission measuring system has been developed in Kokusai Denshin Denwa Company, Ltd., and has successfully been applied in both experimental and manufacturing stages. In this system, the insertion loss or the insertion gain of a test piece is measured automaticaly with an accuracy of 0.001 dB, over the range from 0 to 60 dB, in the frequency range from 0.1 to 100 MHz. In this paper, newly developed precision techniques to attain the aforementioned accuracy are described. In addition, the characteristic features of computer controlled techniques that resulted in measurement flexibility and improved the accuracy of the measurement are also presented.

The expanding role of semiconductor devices in telecommunications

The junction transistor made its first impact on telecommunications in transmission systems, then entirely analogue, effectively by replacing thermionic valves. later developments of that transistor have made possible systems enabling over 10 000 telephone channels to be carried on one 9.5 mm diameter coaxial tube. submarine cable systems have also benefited from the development of highly reliable wideband transistors, with a 1800-circuit single-cable system now in production for intercontinental working. recently, telecommunications satellites, owing their success electronically to several different classes of semiconductor device, have challenged repeatered cables, offering even higher capacities.Exploitation of the transistor as a logic or switching device followed the early analogue applications, with 24-channel digital transmission systems using pulse code modulation. the control of switching systems was soon demonstrated, with intensive follow-up, even though metallic contacts through which the audio signals are routed in public telephone exchanges have not yet been supplanted.Some systems under development demand special devices, e.g. solid-state sources for frequencies up to 100ghz for both guided and new free-space microwave systems. guided optical communications make desirable a long life, room-temperature-operated, high duty ratio gallium arsenide laser. integrated circuits will find a very wide range of use throughout.

The manufacture of highly reliable transistors for submarine cable systems : J. Auchterlonie, D. Baker, D. J. Sargent and A. W. Searls, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 103

The manufacture of highly reliable transistors for submarine cable systems : J. Auchterlonie, D. Baker, D. J. Sargent and A. W. Searls, IEE Conf. Reliab. Electron., Conf. Publ. No. 60, 10–12 December (1969), p. 103

SF System: Repeater and Equalizer Design

Long-distance submarine cable transmission systems require precise, highly reliable repeaters for amplification, and adjustable equalizers for reducing accumulated transmission deviations. This article describes the problems and solutions in designing suitable repeaters and equalizers for the high capacity SF System. This system uses a repeater with transistors to provide a capacity of 800-message circuits.

SF System: Transmission Tests, Computations and Equalization During Installation

The SF Submarine Cable System relies on equalization of accumulated misalignment at regular intervals along the length of the system to achieve performance objectives. Transmission tests of the undersea system during installation are required to implement this equalization. This article describes the tests that are conducted and the computations used to select equalizer settings just before an equalizer is overboarded.

SF System: Shore Terminal Facilities and Fault Location

A special shore terminal transmission facility has been developed for the SF Cable System. The multiplex portion differs from similar domestic plant in that the frequency allocation follows international standard, and can operate with 8-kHz as well as conventional 4-kHz spaced message channels. High reliability is achieved through duplication of equipment combined with added failure detection circuitry and protection switching. Additional features include broadband flexible equalization capability to optimize transmission performance, a separate 4-channel order wire, and automatic pilot measuring equipment. From the point of view of physical design, two departures from conventional practice are the use of shorter than normal bay frameworks and enclosures to cover them. both of which are compatible with foreign design practice. Newly designed test equipment enables monitoring undersea performance and fault locating from the shore terminal. Inclusion of a supervisory oscillator in each repeater is a major change from previous submarine cable systems.

High Speed Submarine Optical Fiber Communication System:Pressure and Temperature Effects

In the present paper, the performance of high speed submarine optical fiber cable systems is investigated, taking into account both the pressure and the temperature effects. Both the pressure and the temperature are depth-dependent variables, while both the spectral losses and the dispersion effects are temperature as well as wavelength dependent variables. Two important cases with real fibers are processed: a case with dispersion cancellation and a case without dispersion cancellation. It is found that the ocean pressure (due to the depth) shifts the dispersion-free wavelength towards the third communication window. In general, as the depth increases the maximum transmitted bit rate increases in the range of interest. The system capacity as well as the spectral losses, and the dispersion effects are parametrically investigated over wide-range ranges of the set of affecting parameters {wavelength, ocean depth (and consequently the ocean pressure and temperature), and the chemical structure}. Key Words: Submarine Optical Fiber, Undersea Optical Communication, Pressure and Temperature Effects, Transoceanic Optical Communications

Overload Stability Problem in Submarine Cable Systems

Modern submarine cable systems usually provide bidirectional transmission over a single cable with repeaters which use a common amplifier for both directions of transmission. The signals for the two directions of transmission occupy separate frequency bands. Under normal loads, the amplifier is highly linear and there is negligible interaction of the signals in the two bands. However, when approaching overload, intermodulation in the repeaters may transfer appreciable power between bands. It has been discovered that this feedback, especially in the presence of large misalignments, can result in a system that maintains itself in overload. Such a system, once excited by a momentary signal or noise peak, generates sufficient intermodulation noise to keep itself overloaded, even in the absence of any further external signal. This paper describes the occurrence which drew attention to this phenomenon, presents an analytical approach used to predict stability margins for any given repeater, and describes the action taken to ensure the stability of the SF Submarine Cable System.

Equivalent electromechanical representation of trapped energy transducers

Trapped energy resonators and transducers have attained a considerable importance in quartz crystal technology both as single-frequency resonators for the control of crystal oscillators and as drivers for the monolithic crystal filter which appears likely to have a wide use as a channel filter for the separation of voice frequency channels for long-distance carrier systems, microwave radio, and submarine cable systems. It is the purpose of this paper to derive the equations for trapped energy resonators of the thickness-shear and thickness-twist types and to calculate the ratios of capacitances for straight crested waves. It turns out that the ratios are lower (coupling higher) than are observed in practice. It appears that this difference is connected with the finite width of the plate which causes the motion at the edge of the plate to be somewhat smaller than the motion in the center of the plate. While no exact solution has been obtained for the finite plate, an approximation is made which is in good agreement with the experiment. The resonator on a plate is a symmetrical device, whereas a transducer for driving a monolithic filter is a dissymmetrical device since it is driving different impedances on its two boundaries. To represent this dissymmetry requires a distributed network representation which is somewhat similar to that found for a plane longitudinal or shear wave except that the propagation constant for a trapped wave replaces that of the plane wave. The representation also requires a transformer whose transformation ratio is a function of the frequency and two negative element terms. By transformations the negative elements can be made to disappear. These together produce an equivalent circuit whose values depend on the ratio of the electrode length to the crystal thickness.

An ocean platform and submarine cable system for the North Atlantic : Wood K.A., 1965. J. Inst. Navig., 18 (4): 437–445

An ocean platform and submarine cable system for the North Atlantic : Wood K.A., 1965. J. Inst. Navig., 18 (4): 437–445

An Ocean Platform and Submarine Cable System for the North Atlantic

The paper proposes highly stable moored ocean platforms and a transatlantic submarine telephone cable to provide a reliable v.h.f. communication service and other A.T.C. facilities to civil aircraft on the main air routes across the North Atlantic. The main features of the platform and cable system are discussed and some idea of the time scale and costs is given.The planning of facilities needed to enable future operations over the North Atlantic to accommodate reduced separation standards and to satisfy the specialized requirements associated with operating S.S.T. aircraft has emphasized the present unsatisfactory standard of communication services in the area.

Cable and Repeater Handling System

This paper describes the development of methods and equipment for handling cable and repeaters in laying submarine cable systems and the application of these developments to C.S. “Long Lines.” Both the laying process and the associated operation of assembling the system components in preparation for laying are described.

A Cable Laying Facility

In order fully to utilize new broadband submarine cable systems it has been necessary to consider new techniques for placing the system on the ocean bottom. This article describes the general development plan that resulted in a new cable ship capable of efficiently handling any new system. The article thus serves as an introduction to the remaining articles of this special issue.

Repeaters and Equalizers for the SD Submarine Cable System

An equivalent four-wire repeater and an adjustable equalizer are described. The repeater incorporates a low-aging design to reduce the effect of electron tube gain changes. The equalizer contains a number of bridged-T networks, some of which can be switched in or out by a selector. The high-pressure container which houses either unit is made up of a beryllium copper cylinder with welded dome covers. Electrical connections are made through polyethylene-metal seals.

The SD Submarine Cable System

Submarine cable systems of a new design have recently been installed between Florida and Panama, between New Jersey and Cornwall, England, and between Hawaii and Japan. Using a single lightweight armorless cable for most of the route, with electron tube amplifiers encased in rigid containers at 20-mile intervals, this type of system will carry 128 channels in each direction. More detailed discussion of cable, repeaters, and power equipment will be found in companion articles. This article outlines the system development objectives, gives an over-all system description, and describes the equalization plan and terminal equipment.

Design and Powering of Cable Ship “Long Lines”

The C.S. “Long Lines” was designed both to lay the new SD submarine cable system and to repair new and existing undersea cables. Within the limits imposed by this dual purpose, an entirely new cable ship design has been evolved which gives maximum working efficiency, maneuverability, and stability. While most of the special features of the ship — wide-range power plant, cable storage and handling facilities, etc. — are the result of its special function, a great deal of attention has been paid to providing optimum working conditions for, and safety of, the ship's complement.

Cable Payout System

This paper describes the development of cable machinery and control equipment capable of laying modern submarine cable systems. The necessity for reliable continuous operation is established, and the problems involved in gripping armorless cable are pointed out. The concept of a linear cable engine is introduced, and the evolution of a track design is followed through several model stages. The various test programs employed to establish feasibility, prove-in component reliability, and check performance of the final machine are discussed. A control philosophy is presented and the development of a control system is described. Final design, construction, and testing of the cable machinery and its control equipment are covered briefly.