Page 1 of 7 Title Demonstrate knowledge of telecommunications cable systems Level 4 Credits 20 Purpose This unit standard covers underpinning knowledge necessary for technicians employed in installation and maintenance of telecommunications cable systems. People credited with this unit standard are able to demonstrate knowledge of: transmission line concepts relevant to cable systems; basic concepts of modulation and multiplexing; the construction and properties of telecommunications cables; the principles and practices of typical PCM bearer systems from a cable systems perspective; the principles and practices of a typical coaxial cable distribution system from a cable systems perspective; the principles and practices of fibre optic cable systems from a cable systems perspective; and the principles and practices of a typical cable pressurisation system. Classification Telecommunications > Telecommunications - Service Delivery Available grade Achieved Guidance Information 1 References Building Act 2004; Electricity Act 1992; Electricity Safety Regulations 2010; Health and Safety at Work Act 2015, and associated regulations; Local Body regulations; and all subsequent amendments and replacements. 2 Definitions AM amplitude modulation. Cable any or all of copper cable, fibre optic cable, coaxial cable. Cable systems one or more sections of cable with access terminations at each end, and all intermediate plant and equipment necessary for the successful transmission of signals. Typical intermediate plant and equipment includes joint enclosures, man holes, poles, amplifiers, regenerators, repeaters, pressurisation plant, power feeding, organisers, and terminal frames. FDM frequency division multiplexing. FM frequency modulation.
Page 2 of 7 Industry practice those practices, which competent practitioners within the industry recognise as current industry best practice. Outside plant that portion of the telecommunications network that generally extends from exchange switch to the point of entry at customers premises. This may include the distribution side (D side) of the main distribution frame (MDF). PCM pulse code modulation. QAM quadrature amplitude modulation. QPSK quadrature phase shift keying. Specifications any or all of: detailed job specifications, drawings, and instructions; manufacturers specifications and instructions; and industry codes of practice relating to the type of cabling system being installed. TDM time division multiplexing. 3 The phrase in accordance with industry practice is implicit in all performance criteria in this unit standard. Outcomes and performance criteria Outcome 1 Demonstrate knowledge of transmission line concepts relevant to cable systems. 1.1 Transmission parameters are defined and units stated. primary constants, decibel level, loss, psophometric noise; variation of loss with reference to frequency; characteristic impedance; bandwidth; near and far end crosstalk; bit error rate; loop resistance. 1.2 Typical application of paired, coaxial, and optical fibre cables are stated with reference to transmission loss and bandwidth. reference to primary constants, definition of transmission losses, variation of loss with frequency, characteristic impedance, reflections, termination, noise, near end and far end crosstalk. 1.3 The conditions for maximum transfer of signal power to load are explained with reference to reflections and terminating impedance. Also, the use of high and low impedance terminations are explained in terms of effects on signal measurements and the network, if wrongly used. 1.4 The principles of modifying line characteristics by means of equalisers, cable simulators, and loading coils are explained, with reference to inductance, resistance, and capacitance, and the effects on loss and bandwidth. 1.5 Loop resistance and decibel loss at a given frequency for a given cable length and type are calculated from standard cable data.
Page 3 of 7 Outcome 2 Demonstrate knowledge of basic concepts of modulation and multiplexing. 2.1 Basic concepts of modulation are explained in non-mathematical terms with the aid of sketches showing typical waveforms before and after modulation, and with reference to a typical application. modulation AM, FM, QAM, QPSK. 2.2 Basic concepts of FDM and TDM are explained with the aid of sketches, and with reference to one typical application for each method. Outcome 3 Demonstrate knowledge of the construction and properties of telecommunications cables. 3.1 The properties of paper or plastic insulated cables are described. physical properties pair makeup, insulation, sheaths, conductor diameter, colour code, electrical properties and loop resistance, loss at audio and high frequencies, near and far end crosstalk, bend ratio. 3.2 The properties of coaxial cables are described. physical properties cable makeup, insulation, sheaths, conductor dimensions, electrical properties, transmission loss versus frequencies, bend ratio, dielectric constant. 3.3 The properties of optical fibre cables are described. physical properties fibre makeup, insulation, sheaths, fibre diameter, loose tube and slotted core, single and multi mode, bend ratio, twisting and helix factor, internal and external cable, transmission properties, typical signal loss versus frequencies, typical joint losses. Outcome 4 Demonstrate knowledge of the principles and practices of typical PCM bearer systems from a cable systems perspective.
Page 4 of 7 4.1 Principles of typical PCM line links are described with the aid of a block diagram showing all major components. reference to encoding and decoding speech signals, line code, bit rate, regenerators, factors affecting regenerator spacing, line terminal, power feeding, housings including pressurisation, supervisory systems, crosstalk. 4.2 Methods of jointing cables to regenerator housings are explained with the aid of sketches. The explanation must include reference to minimisation of cross talk and pressurisation practices. 4.3 Acceptance test procedures for the installation of a typical digital link are described with reference to type of tests, test instruments, and typical limits. types of measurements loop resistance, insulation resistance, bit error rates, flood testing. 4.4 PCM line fault finding procedures are described in accordance with industry practice. reference to use of supervisory systems, loop back regenerator cards, bit error rate measurements, use of PCM line test set, time domain reflectometry. 4.5 PCM line plans and specifications are interpreted in accordance with industry practice. Outcome 5 Demonstrate knowledge of the principles and practices of a typical coaxial cable distribution system from a cable systems perspective. 5.1 Principles of a typical coaxial cable distribution system are described with the aid of a block diagram showing all major components. reference to nature of line signals, line terminals, amplifiers, factors affecting amplifier spacing, power feeding, housings including supervisory systems. 5.2 Methods of terminating coaxial cable at housings are explained, including reference to expansion loops. 5.3 Acceptance test procedures for the installation of a typical coaxial cable distribution system are described with reference to type of tests, test instruments, and typical limits.
Page 5 of 7 5.4 Coaxial cable fault finding procedures are described in accordance with industry practice. 5.5 Coaxial cable plans and specifications are interpreted in accordance with industry practice. Outcome 6 Demonstrate knowledge of the principles and practices of fibre optic cable systems from a cable systems perspective. 6.1 Principles of typical fibre optic cable systems are described with the aid of a block diagram showing all major components. reference to nature of line signals, line terminals, regenerators or repeaters, factors affecting regenerator or repeater spacing, line terminal power feeding, housings, fibre organisers, optical line terminal equipment, splicing trays, supervisory systems. 6.2 Fibre cable is spliced using fusion and mechanical splicing methods according to industry practices and standards applicable to the type of cable used. attention to opening and closing organiser trays and other enclosures, laying of fibres into trunking and organiser trays, bend ratios, splice protectors, joint closure, labelling, loss measurement; evidence of a total of five splices, with acceptable individual and average splice losses, of one type of cable is required. 6.3 Acceptance test procedures for the installation of a typical fibre optic cable system are described with reference to type of tests, test instruments, typical limits. 6.4 Optical fibre cable fault finding procedures are described in accordance with industry practice. reference to use of supervisory systems, optical time domain reflectometry, visible light source, fibre identifier, fibre tool kit, fibrefones, cold clamping, cable metre marks, commissioning information, cable helix factor, fibre retraction. 6.5 Safety precautions applicable to optical fibre cable systems are explained in accordance with industry practice. reference to laser radiation, classification of laser products, labelling, glass splinters, cleaning chemicals, protective equipment and clothing, tools.
Page 6 of 7 6.6 Optical fibre cable plans and specifications are interpreted in accordance with industry practice. Outcome 7 Demonstrate knowledge of the principles and practices of a typical cable pressurisation system. 7.1 Purpose and principles of a typical cable pressurisation system are described with the aid of a block diagram showing all major components. reference to pneumatic principles, flow panel, pressure, air drier, filtration, cable connection, cable sealing. 7.2 Cable fault finding procedures using a cable pressurisation system are described in accordance with industry practice. reference to flow panel, graphing, pressure testing, use of instruments, leak location using hydrogen. 7.3 Safety precautions applicable to cable pressurisation systems are explained in accordance with industry practice. 7.4 Cable pressurisation system plans and specifications are interpreted in accordance with industry practice. Planned review date 31 December 2020 Status information and last date for assessment for superseded versions Process Version Date Last Date for Assessment Registration 1 20 September 2002 N/A Rollover and Revision Rollover and Revision 2 25 February 2008 N/A 3 23 November 2017 N/A Consent and Moderation Requirements (CMR) reference 0101 This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
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