This course introduces the techniques employed to transmit information over a telecommunications network and the properties of the transmission media employed to carry signals over long distances including copper wires, optical fibre and radio waves. A method of carrying information from different sources over the same transmission link is also explained.
An understanding of the basic properties of analogue and digital signals. It is recommended that the PTT course PAA: "Analogue and digital signals" is studied before attempting this course.
By the end of this course you will be able to:
- explain the conditions for maximum power transfer over a copper cable with reference to its characteristic impedance.
- describe the use of logarithmic units to express power loss and level.
- compare the characteristics and applications of twisted pair and coaxial copper cable.
- describe the principles of the transmission of information over optical fibres.
- describe the characteristics and applications of transmissions in the various frequency bands of the electro-magnetic spectrum.
- describe the principles, capabilities and applications of various types of modulation technique.
- explain the principles of Time Division Multiplexing (TDM) and describe the capabilities of TDM signals as used in modern telecommunications networks.
- describe the role, characteristics and format of the various types of signal transmitted over copper and optical cable systems.
Module 1: Introduction
reference to its characteristic impedance and describe the use of logarithmic units to express
power loss and level.
- describe the equivalent circuit model of a transmission line in terms of resistance, capacitance and inductance.
- explain the concept of characteristic impedance.
- state the conditions for maximum power transfer between a source and a load.
- list typical values of characteristic impedance for various types of cable including co-axial cable and twisted pairs.
- explain the terms power level, loss, and gain.
- define the units “decibel” (dB) and “dBm” and compare their relevance and use.
- calculate the output power of a circuit in dBm units from the individual losses in the circuit (in dB) and a given input power (in dBm).
- After completing this module, a trainee will be able to:
- compare the configuration of an unbalanced pair of wires to a balanced pair.
- explain how a balanced pair of wires provides a higher immunity to interference with reference to the common mode rejection (CMR) of induced signals.
- explain that the twists in a twisted pair of wires enhance CMR.
- define, and explain the relevance of, nominal velocity of propagation (NVP) and “delay skew”.
- describe and compare the basic construction of unshielded and shielded twisted pair cables,
- compare their capabilities and give typical applications.
- describe the basic construction of coaxial cable and give typical applications.
- describe the role of baluns.
- describe the basic structure of an optical fibre in terms of its core and cladding and explain how optical energy propagates down a fibre.
- define the term “acceptance angle” and explain its relevance to the choice of optical source.
- describe the capabilities of optical fibre compared with copper wires and give typical applications of optical fibre.
- describe and compare the structure and characteristics of singlemode and multimode fibre.
- explain the causes of loss in optical fibre in terms of scattering and absorption and describe how the choice of operating wavelength depends on the loss characteristics of a fibre.
- explain the basic principles of Wave Division Multiplexing (WDM).
- describe how WDM allows bi-directional operation over a single fibre and the sharing of a fibre by several traffic streams.
describe the various propagation modes of electromagnetic radiation (EMR) with reference to line of sight and groundwave propagation, ionospheric refraction, tropospheric scattering, reflection and diffraction.
explain that each type of radio system depends on a particular EMR propagation mode or a combination of modes.
- explain the role of modulation in the transmission of data over both wired and wireless links.
- explain the principles of amplitude modulation (AM) and describe the characteristics of an AM wave in terms of the occupied bandwidth and effects of noise.
- explain the principles of Frequency Shift Keying (FSK) and describe the characteristics of an FSK wave in terms of the occupied bandwidth and effects of noise.
- explain the principles of Phase Shift Keying (PSK) with reference to the relationship between the number of permitted states, the maximum achievable data transfer rate and immunity to noise.
- explain the principles of Quadrature Amplitude Modulation (QAM) with reference to the relationship between the number of permitted states, the maximum achievable data transfer rate and immunity to noise.
- describe the benefits of Gaussian Minimum Shift Keying (GMSK) compared with FSK.
- give examples of the applications of AM, FSK, PSK, QAM and GMSK.
capabilities of TDM signals as used in modern telecommunications networks.
describe the benefits of TDM with reference to sharing link resources while offering a guaranteed bandwidth and minimum delay for individual circuits.
describe the structure and payload capability of an E1 primary multiplex frame.
explain the benefits of the Synchronous Digital Hierarchy (SDH) in terms of the multiplexing flexibility and the availability of a comprehensive set of ITU recommendations.
explain that TDM-based networks are synchronous in operation and depend on the distribution of timing signals from a centralised clock.
list and compare the bit rates and payload capabilities of European SDH and North American SONET aggregate signals.
- explain the purpose of a line code with reference to the bandwidth efficiency and dc component of a transmitted signal, and the requirement for timing extraction and error checking.
- describe methods of improving timing extraction including the use of zero (RZ) signals.
- explain the advantages of bipolar line codes with reference to error checking and the reduction in the DC component of a signal.
- explain that a multi-level line code reduces the bandwidth requirement of a signal but also reduces its noise immunity.
- give examples and applications of line codes including Manchester encoding, CMI, AMI, HDB3 and 2B1Q.
- explain the basic principles of block coding with reference to error checking, bandwidth requirement and use with optical signals.
Who Should Attend
This course is designed for those who require an introduction to the fundamental technical concepts that underpin modern telecommunications. The course is suitable for those joining the industry in a technical role especially those in an apprenticeship.