Coaxial Cable System Research Articles

Water Pressure Measurement with Time Domain Reflectometry Cables

Abstract Attributes of the remote measurement of piezometric water pressure and water level with time domain reflectometry (TDR) techniques are investigated. The evaluation includes a two-wire system for unusually small riser tubes as well as parallel wire and air-filled or hollow coaxial cable for typical installations. Comparison of TDR cable and commercial pressure transducer technology shows coaxial cable TDR systems with distance crimps capable of equaling and exceeding the resolution of pressure transducers. Crimps provide permanent distance markers that allow the TDR system to be self-calibrating.

95/01554 Modified fourier transform lighting surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

95/01554 Modified fourier transform lighting surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

95/01555 Modified FT lighting surge analysis of an overhead line-underground coaxial cable system. Part I. Modal analysis of underground cables and overhead lines and effect of subterranean water on cable modal propagation characteristics

95/01555 Modified FT lighting surge analysis of an overhead line-underground coaxial cable system. Part I. Modal analysis of underground cables and overhead lines and effect of subterranean water on cable modal propagation characteristics

Modified Fourier transform lightning surge analysis of an overhead line-underground coaxial (CV) cable system Part II. System lightning surge response

The lightning surge analysis of an overhead line-underground CV cable transmission system has been carried out using the modified Fourier transform with a multiconductor representation. The frequency dependence of the transmission system components such as the overhead transmission line, underground cable and towers has been analyzed. A digital simulation based on this analysis has been developed and applied to a 77 kV three-phase single-circuit system. The results for a direct hit by a lightning stroke at the riser pole tower top show that the overvoltages at the riser pole increase with increase in the tower footing resistance and that the phase conductor overvoltages are greatly affected by the CV cable. The cable open-tie overvoltages decrease with increase in the cable length.

Modified Fourier transform lightning surge analysis of an overhead line-underground coaxial (CV) cable system Part I. Modal analysis of underground cables and overhead lines and effect of subterranean water on cable modal propagation characteristics

In the first part of this paper, the modal analysis of a CV underground transmission system is investigated. A digital computer program is developed and applied to 77 kV three-phase single and double circuits. The dependence of the velocity and attenuation characteristics of the natural modes of propagation on the frequency is illustrated and their considerable dependence on the subterranean water which may accumulate in the ducts is demonstrated. In the second part, a digital computer program is developed to investigate the dependence of the transmission line parameters and their modal characteristics on the frequency ( Electr. Power Syst. Res., 31 (1994) 43–49). A 77 kV three-phase single circuit has been used as a test system for the program. The effect of inclusion of the ground wire, for lightning surge investigations, on the modal analysis is illustrated. The results are discussed in connection with the electromagnetic transients.

Optical fiber transmission of multi-channel FM audio and video signals

An optical-fiber transmission system with a bandwidth of greater than 100 MHz for transmitting multichannel FM audio and video signals is described. This system for distributing FM audio and video signals on up to five channels to the respective receiver was constructed using a high-speed LED (light-emitting diode) and a wideband amplifier. The differential gain and differential phase were less than 2% and 3 degrees , respectively, and the SNR was 56 dB. The proposed system will be used for high-quality, high reliability distribution of multiple TV channels instead of the coaxial cable distribution systems. >

Application of phase-stabilized optical fiber in transmission of reference and IF signals in VLBI observation

A phase-stabilized optical fiber (PSOF) cable, which is 880 m long, was successfully used to transmit a 100-520 MHz IF signal and 10 MHz reference frequency signal in Mark III very long baseline interferometry (VLBI) observations. Phase stability of the 1760-m round-trip PSOF cable was measured by a dual mixer time difference system. Results of the measurements show that the stability of the PSOF cable system is about 50 times better than that of an ordinary coaxial cable system. The measured phase fluctuations are smaller than the tolerance limit required for a coherence loss of less than 20% in VLBI observations with an integration time of several hundred seconds. Internal accuracies of the international geodetic VLBI observations, in which the PSOF cable system is used at a station, are proven to be in the level of the present-day standard. The results show that the performance of the cable is at least comparable with, and probably better than, that of coaxial cables of much shorter length widely used in VLBI stations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A high-quality switched FM video system

At issue in the delivery of broadband cable television services is whether their promise will be realized through the adoption of a revolutionary switched distribution system or an evolutionary upgrade to the existing broadcast, tree-and-branch coaxial cable television systems. This issue is examined in the context of the key factors of economics and consumer demand. Architectural objectives established to satisfy likely cable television system requirements five to ten years in the future are highlighted. A high-quality switched video system optimized for the likely cable television requirements of the later 1990s is described, both as conceptualized and as proven in the laboratory. The headend, switch and upconverters, optical link, tap, set-top unit, and link performance are described, and laboratory results are presented. Hurdles standing in the way of large-scale commercial viability are identified. >

Materials Aspects of the SL Lightguide Undersea Cable Design: 1988 MRS Spring Meeting Plenary Addres

Starting in the 1950s, AT&amp;T has been involved in the design, installation, and operation of undersea coaxial cable systems to provide international and inter-island telecommunication services. These systems are analog transmission systems, utilizing frequency division multiplexing to simultaneously transmit multiple channels over a single cable. With the passage of time, and in response to an ever growing demand for services, the frequency bandwidths of successive systems have been increased to accommodate the need for increased traffic density. The increases in bandwidth have been accompanied by increases in copper ohmic losses, brought about by the skin effect phenomenon, mandating ever shorter spacing between repeaters, and consequently larger numbers of repeaters for a given system length. The reliability outlook for extending coaxial cable technology beyond its present capacity, with a decrease in repeater spacing below the current value of about 9 km, is not favorable.Fortunately, we now have available optical fibers for transmission media. Unlike coaxial cable, the fiber medium is not limited by the skin effect phenomenon. Using fiber technology, we can transmit large amounts of traffic through a very small cross-sectional areas, using repeaters at infrequent intervals. Moreover, undersea fiber optical systems utilize digital (as opposed to analog) transmission, a format extremely advantageous in terms of transmission quality and the types of services that can be offered.

Design considerations for broadband coaxial cable systems

Design considerations for broadband coaxial cable systems

Recent advances in submarine optical fiber cable transmission systems in Japan

Submarine optical fiber cable transmission systems are promising successors to existing submarine coaxial cable systems. This paper will review the history and the state of the art of the submarine optical fiber cable transmission technology, and the submarine optical fiber cable transmission systems named FS-400M and OS-280M being developed by NTT and KDD, respectively, in Japan.

A Coaxial Cable Delay System for a Synthesis Radio Telescope

A switchable coaxial cable delay system for path compensation in a synthesis radio telescope operates over the frequency band 15-45 MHz. The requirements of continuum and spectral line observations determine the system specifications. Diode switches include or exclude cables whose lengths form a binary sequence from 0.625 to 320 m. Cables are equalized to compensate for the effects of frequency dependent attenuation and of dispersion. A simple technique for dispersion equalization is described.

Espenschied and strieby on a coaxial cable communication system

Espenschied and strieby on a coaxial cable communication system

Reliability-Growth Programmes For Undersea Communication Systems

This paper deals with the unique problems encountered when managing reliability growth programmes on expensive capital equipment components destined for use in a relatively inaccessible environment. Continuous operation of these components in predominantly non-redundant configurations is required for up to 25 years; and repair costs and/or lost revenues incurred by single failures at anytime during this period can amount to several $100 000. After a brief review of the history and philosophy of reliability growth programmes on components for coaxial cable systems, the planning, development, and implementation of reliability assurance procedures for undersea systems designed for 1.3 ?m optical transmission at 280 Mbit/s are addressed. The challenge involved in proving electro-optic and electronic components suitable for undersea optical PCM systems is not to be underestimated. Even in a relatively benign environment, these systems have specific problems with respect to operating temperatures, voltage stresses, heat dissipation factors, and the lack of escape routes for trapped contaminants. The components themselves are not only relatively new, or just emerging from the development phase, they also demand innovative reliability assessment techniques because of the inadequacy of traditional methods of accelerated testing. This paper gives an insight into some of these problems from a reliability management viewpoint. It is increasingly evident that QC and RA programme leadership cannot now, if it ever could, be accomplished without detailed knowledge of sophisticated component design.

A simple in-service error detection scheme based on the statistical properties of line codes for optical fibre systems

Abstract An investigation has been carried out into the practicability of adapting a scheme of in-service error monitoring at dependent repeaters, currently used on British Telecom 140 Mbit/s coaxial cable systems, for possible incorporation in the supervisory subsystem of future generation 140 Mbit/s optical fibre digital line systems. Attention has been focused on the use of the technique in systems employing binary alphabetic line codes of the form mBnB. In particular, in-depth studies on the performance of the error-detection circuit for 7B8B line codes, which are attractive for 140 Mbit/s optical systems, are reported.

A Repeater Fault Locator Using a Correlation Technique for a Submarine Coaxial Cable System

This paper introduces a correlation technique in order to accurately measure intermodulation products from repeaters within a short period of time (about one hour and a half per 1000 km). A pair of PN sequences, whose cross-correlation function has a zero sidelobe, has been designed to reduce interference by other products, and to obtain the necessary signal-to-noise ratio (more than 50 dB). As an example, design objectives and results for a repeater fault locator in a 140 MHz submarine coaxial cable system are described.

Undersea fiber cable technology

Compared with the conventional coaxial undersea cable systems, an optical fiber undersea cable system has a great technical and economical advantage. It is also suitable for digital transmission. In this paper, the optical fiber undersea cable technology (including optical fiber cables and repeaters), which is now in the research and development stage in several countries, is reviewed.

Systems aids in determining Local Area Network performance characteristics

At Bethesda, Maryland, the National Library of Medicine has a large array of heterogenous data processing equipment dispersed over ten floors in the Lister Hill Center and four floors in the Library Building. The National Library of Medicine decided to implement a more flexible, expansible access medium (Local Area Network (LAN) to handle the rapid growth in the number of local and remote users and the changing requirements. This is a dual coaxial cable communications system designed using cable television (CATV) technology. One cable, the outbound cable, transfers information between the headend and the user locations. The other cable, the inbound cable, transfers information from the user locations to the headend. This system will permit the distribution of visual and digital information on a single medium. On-line devices, computers, and a technical control system network control center are attached to the LAN through BUS Interface Units (BIUs). The technical control system will collect statistical and status information concerning the traffic, BIUs, and system components. The BIUs will, at fixed intervals, transmit status information to the technical control. The Network Control Centers (NCC) will provide network directory information for users of the system, descriptions of the services available, etc. A X.25 gateway BIU will interface the LAN to the public networks (Telenet and Tymnet) and to X.25 host computer systems.

Undersea Fiber Cable Technology

Compared with the conventional coaxial undersea cable systems, an optical fiber undersea cable system has a great technical and economical advantage. It is also suitable for digital transmission. In this paper, the optical fiber undersea cable technology (including optical fiber cables and repeaters), which is now in the research and development stage in several countries, is reviewed.

General expressions for attenuation‐characteristics of submarine coaxial cables at high frequency

AbstractAn expression for the attenuation loss of submarine coaxial cable systems must provide a precisely calculated attenuation loss at any frequency in the environments of temperature T and water pressure P. The expression, based on the cable loss characteristics measured at atmospheric pressure on land, must yield an accurate estimate of the cable loss characteristics at the sea bottom.Here, we propose a general expression for the attenuation as a function of f, T and P. The expression is based on some material characteristics and sizes, which are the basic parameters defining the transmission characteristics of a submarine coaxial cable. Owing to the introduction of a polynominal representation for the dielectric loss characteristic tan δ which has hitherto not been taken into account, we were able to derive an expression for the attenuation vs. temperature and water‐pressures and to demonstrate explicitly that variations in attenuation caused by temperature and water pressure changes can take the form of polynominal equations in f, T and P. Further, we shall introduce a finite‐order, simple and practical polynominal formula as. an expression for the case when some limitations are allowed on the frequency and on the accuracy of calculating the attenuation.