Telecominications_Report

Introduction: Communication is the process of transmitting information from a source to a receiver. The rapid transmissions of information over long distances and easy access to information have become vital features of the modern world. In transmitting data from source to receiver, energy is transformed from one form into another. As technology advances, there has been tremendous development in communication of large amounts of digital data. Engineers now aim to transmit large amounts of data as efficiently and cost effectively. This takes advantage of current technologies of Coaxial cables, Fibre Optics and Microwave transmitters and uses them appropriately in order to communicate large amounts of digital data. Method: The investigation to be carried out in order to determine the practicality and capability of the various methods of data communication involved looking at the material used in each component in each of the methods of data communication. Along with each methods ability to improve the communication between two cell phone towers. Another vital part of the investigation included looking at coaxial cables, Fibre Optics and Microwave transmitters’ components including durability, construction. Installation, reliability, longevity and other factors that may affect its performance in effectively communicating large amounts of digital data. This involved the rate of data transfer and frequency for Coaxial cables, Fibre Optics and Microwave Another aspect that was considered was the level of security, as increased technological awareness has raised the amount of hackers into these systems, which now need to have ways to maintain their levels of security. All these aspects are important as they dramatically affect the practicality and effectiveness of the method and resulted in determining the preferable form or forms of communicating large amounts of digital data. The data used to obtain results and further discuss Coaxial cables, Fibre Optics and Microwave transmitters practicality and effectiveness in communicating large amounts of digital data over 20km was gather from various reputable sources on the internet and in books with specific information that was relative to Coaxial cables, Fibre Optics and Microwave transmitters. Link Type No. of 2 way conversations Cable Size Comments Coaxial cable 2700 2 cables, each with 50 tubes Each tube 9.5mm thick. Repeaters every 45km Microwave Radio 1920 140 Mbit/s system Expensive repeater towers every 50 km Optical fibre 28,720 30-fibre cable 12mm thick. Repeaters every 35-55 km Results: Coaxial Cables- A coaxial tube consists of an outer conductor which is a hollow metal tube, usually copper, about a centimetre in diameter, with an inner conductor, usually a solid wire a few millimetres in diameter, running along inside it. The inner wire is kept centred in the outer tube by means of polythene discs spaced at regular intervals throughout the tube. Apart from the polythene discs, the inner conductor is kept insulated from the outer tube simply by air. Such tubes are called coaxial because the two conductors share the same centre, or axis. The cable is designed to carry a high-frequency or broadband signal, as a high-frequency transmission line and can be packed closely together without fear of interference, and that particularly at high frequencies, there is very little attenuation (refer to appendix A) or loss of signal strength over distance, as energy is not lost readily from the tube because of its shielding effect. In metropolitan areas, coaxial cables are installed in underground ducts. However, in country areas, and over long-distance routes, the cable is buried about a metre deep once the cable is laid, the coaxial tubes are pressurised, so that any hole or break in the tubes causes an escape of air. This both keeps out dust and allows the break to be detected a long distance away, due to the drop in pressure, which can be detected by special instruments. Modern Six Tube Co-Axial Cable Cables that need to be spliced together in the field require a slow, careful process. The exclusion of dust is a high priority, and the joint must be carefully tested. It is more expensive than standard telephone wire; it is much less susceptible to interference and can carry much more data than a telephone wire. Microwave transmission.- Microwaves are high-frequency (usually from 1-30GHz) radio waves that can only be directed in straight lines. For this reason, it is necessary to set up microwave repeating stations within line-of-sight of each other. As a result of greater sight from higher up, microwave transmitting and receiving antennas are set on tall towers. These antennas are usually parabolic dishes, which are the same sort of shape as the mirrors in powerful searchlights, and for the same reason Consequently, microwave transmission is usually limited to communications occurring within the limits of a particular city or community. Microwaves received by an antenna on one of the towers are guided by a hollow metal tube (called a waveguide) from its focus, down the tower and into equipment at the tower base. The function of this equipment is to boost the incoming microwave signal and re-transmit it up another waveguide and to an antenna. The curvature of the earth, along with the height of trees or other vegetation must be taken into account on the route to prevent interference. Furthermore the presence of a water surface, such as a lake in the mid-path of the radio path can result in undesirable reflection along with effects of atmospheric stratification (refer to appendices B) that cause the radio path to bend downward and is possible to increase the earths curvature by a bit over 2000km. Rare events of temperature and humidity can produce large deviations and distortion of the propagation and affect transmission quality. The final route of towers is never an exactly straight line. This is deliberate, and is done to avoid the possibility that signals from one tower might "overshoot" its neighbour and interfere with signals at the following towers. The vast majority of the public perceive Microwaves as dangerous radiation, which is not really correct as the power levels would be about be very low, making it safe. Data communication systems utilising microwave technology give high data transmission and reliability, both in continuous and event data transmission modes over long distances. These systems should be designed very precise, therefore, the cost of their implementation is very high as well as the cost of their operation. Fibre Optic Cable- A fibre-optic cable transmits data as pulses of light. Although a fibre Optic cable is diametrically smaller than a human hair, it has 26,000 times the transmission capacity of twisted pair media. A major advantage of fibre Optic data is its high level of security. These communications channels are not susceptible to electronic interference, making them more reliable. Fibre-optic cables are also significantly less expensive than coaxial cable. A disadvantage of fibre-optic channels is that they cannot carry information over great distances. The main component of an optical receiver is a photo detector (refer to appendices C), which converts light into electricity using the photoelectric effect (refer to appendices D). The photo detector is typically a semiconductor-based photodiode. The optical-electrical converters produce a digital signal in the electrical domain from the incoming optical signal, which may be attenuated (see appendices A) and distorted while passing through the channel. Optical fibre cables can be installed in buildings with the same equipment that is used to install copper and coaxial cables. As a result of this and the rising price of copper, the cost of fibre optic cabling is comparable to copper cabling. There are two common types of fibre Optic cables, single mode is more expensive but can provide more distance and Multimode which has a larger diameter cable. Fibre Optic cabling consists of a centre glass core surrounded by Kevlar fibres, strengthening the cable while preventing breakage. The outer jacket is made of Teflon or PVC. It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. It also has the capability to carry information at vastly greater speeds then coaxial cables. This capacity broadens communication possibilities to include services such as video conferencing and interactive services. Discussion: This article discusses the major factors that affect the communication of data. It puts forward three methods that all work on completely different principles. One is the wireless while the other 2 consist of cables. Ultimately there are many factors which need to be taken into account before making a decision on the best available method for communicating large amounts of digital data. Terrain is an important factor in laying cables, where it is difficult to lay over rough ground and can be vulnerable to being cut. Whereas the wireless form of Microwave Transmitters doesn’t suffer from either of these issues. The smaller cable size of Fibre Optics, combined with the relatively cheap infrastructure makes it an appealing option. Whereas the cost for installation of Microwave Transmitters is very expensive, due to their infrastructure and exact position required. Environmentally, fibre optics are small and requires less input then the other forms, notably they can be made from sand. The obvious difference between the rate of data transfer makes Coaxial cables quiet inferior and almost unsuitable as a desirable method of data communication. Optical fibre shows significantly less loss, can support signals demanding much higher bandwidth, is immune to electromagnetic interference (EMI), and enables considerable size and weight savings when compared to coaxial cable. Microwave systems have sufficient bandwidth capacity to support a large number of voice channels and one or two television channels and can achieve high bit rates over moderately long distances. They have been used extensively in inner city data systems where cabling would be very expensive. This is really the only situation where they are viable and Optic Fibre is too difficult or expensive to install. Conclusion: As is evident from the results and discussion Fibre Optics many superior features and components make it a better option in the majority of situations to communicate large amounts of data. Fibre Optics Kevlar outer strengthens it while layer assists in making it lighter, while its production from readily available sand makes it an attractive option for the communication of data. Moreover Fibre Optics offers the following unique characteristics which appear superior to other methods discussed: (i) Enormous potential bandwidth, resulting from the use of optical carrier frequencies around 2 x 1014 Hz; with such a high carrier frequency and a bandwidth roughly equal to 10 per cent of the carrier frequency (ii) Low transmission losses, as low as 0.1 db/km. (iii) Immunity to electromagnetic interference, which is an inherent characteristic of an optical fibre viewed as a dielectric wave guide. (iv) Small size and weight, characterized by a diameter, which is no greater than that of a human hair. (v) Ruggedness and flexibility, exemplified by very high tensile strengths and the possibility of being bent or twisted without damage. Lastly optical fibres offer the potential for low-cost line communications since they are fabricated from sand, which, unlike the copper used in metallic conductors, is not a scarce resource. The unique properties of optical fibres have fuelled phenomenal advances in light wave systems technology, which have, in turn, revolutionised long-distance communications and continue to do so. Ultimately I believe its Fibre Optics Practicality and capabilities that make it the most suitable method for communicating large amounts of digital data. Appendices A). Attenuation-is the gradual loss in intensity of any kind of flow through a medium. B). atmospheric stratification- is the division of the atmosphere into distinct layers, each with specific characteristics such as temperature or composition. C). photo detector- are sensors of light or other electromagnetic energy D). photoelectric effect- is a phenomenon in which electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light.