LEARNING OUTCOMES
The Student Will
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| A | 1. | Describe the Electromagnetic spectrum, the allocation of frequencies to the various services and use logarithmic units to measure system gains and losses. |
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| A | 2. | Investigate and explain encoding techniques used for analogue signals and techniques for modulating radio carrier frequencies. |
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| A | 3. | Describe H.F. transmission lines, and their properties, as they apply to radio frequency transmission and measure signal levels on a H.F. transmission line. |
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| C | 4. | Describe the various signal propagation modes and explain how they are affected by the ionosphere and terrestrial conditions. |
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| A | 5. | Investigate and describe the construction of basic aerials and explain their radiation patterns. |
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| C | 6. | Describe and explain the concept of Spread Spectrum techniques. |
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| C | 7. | Explain error detection and correction techniques used in mobile wireless applications. |
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| C | 8. | Describe Infrared transmission techniques and how these are applied to LAN’s |
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| > | A description of the electromagnetic spectrum and the allocation of frequencies to various services will include; |
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| -frequency bands and their typical application |
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| -services that are suited to higher frequency bands |
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| An explanation of the application of logarithmic units for the measurement of R.F. systems gains and losses will include; |
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| -describing the advantages of the system of logarithmic-based units |
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| -defining a decibel as a logarithmic power ratio and expressing the levels in decibels relative to 1 mW |
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| -calculating losses and gains in a system using measured power, voltage and current |
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| > | An explanation of signal encoding techniques will include; |
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| a)Continuous wave modulation: |
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| -amplitude, frequency and phase modulated carrier |
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| -pulse and sine-wave AM waveforms |
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| -"modulation index" as applied to a DSB AM waveform |
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| -the production of single-sideband and double side-band AM signals |
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| -the comparison of single and double sideband systems with specific reference to power and bandwidth |
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| -the investigation of the operation of simple modulators, demodulators and detectors |
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| -FM waveforms, frequency deviation and modulation index |
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| -A comparison of AM with FM in relation to bandwidth (use of Carson’s rule), power, and signal-to-noise ratio |
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| b)Digital Modulation: |
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| -transmitting an analogue signal as a series of pulses without loss of information |
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| -the minimum sampling rate needed in order to accurately reconstruct an analogue signal |
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| -PAM, PPM, PWM and PCM signal waveforms |
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| -the process of analogue to PAM to PCM conversion |
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| -the process of delta modulation |
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| -compare delta modulation with PCM |
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| c)Digital Radio Modulation: |
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| Digital Modulation techniques, BPSK, QPSK, QAM, p/4 DQPSK, MSK and GMSK |
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| -choice of modulation technique in terms of quality, power, efficiency and bandwidth utilisation |
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| > | A description of H.F. transmission lines and their properties, as they apply to radio frequency transmission, will include; |
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| -a uniform transmission line represented by a Pi or T-Network showing the primary constants |
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| -the characteristic impedance (Zo) of a uniform transmission line |
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| -characteristic impedance expressed as the product of the open circuit and the short circuit impedances and calculated from the primary line constants |
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| -the secondary line coefficients |
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| -primary and secondary line constants as they relate to frequency |
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| -definition of the phase change constant ( ) of a uniform transmission line |
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| -definition of phase velocity (v) of propagation of a wave along a line |
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| -"skin effect" |
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| -the stucture of a co-axial cable and the relationship of its dimensions to Zo and |
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| -the reasons for matching a transmission line to its load |
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| -choosing a particular transmission line for a particular application |
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| -measurement of maximum and minimum voltage values of a HF transmission line under various operating conditions |
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| > | A description of the various propagation modes and an explanation of how they are affected by the ionosphere and terrestrial conditions will include |
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| -ground waves and sky waves |
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| -the effect of refraction in the ionosphere |
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| -skip distance, maximum useable frequency and optimum traffic frequency in non-mathematical terms |
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| -the phenomenon of, and reasons for, fading |
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| -the choice of transmission frequencies in the H.F. band |
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| -the use of the various frequency band allocations (VLF- SHF) |
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| > | A description of the construction of aerials and an explanation of their radiation patterns will include; |
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| -concepts of radiation |
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| -half wave dipole (opened out quarter wave open circuit line (equivalent)) and its electric and magnetic field patterns |
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| -polarisation of an electromagnetic (em) wave and the pictorial representation of an em wave detaching from the local field |
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| -frequencies necessary for efficient radiation |
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| -induction and radiation fields |
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| -transmitting and receiving aerials operating at given frequencies |
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| -the Radiation Resistance of an aerial |
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| -measurement of a half-wave dipole polar diagram with and without the addition of a reflector and director |
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| -aerial gain in terms of an isotropic radiator |
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| -effective radiated power |
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| -the derivation of the Marconi unipole (from the dipole) and measurement of its polar diagram |
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| -the effect of aerial height above ground (graphically illustrated) |
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| -measurement of the forward and reverse power of an aerial feed as the aerial length is varied |
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