Electronics and Testing Concepts

Specialized Testing

• Voltmeters measure the voltage of a circuit and are connected in parallel.
• Ammeters measure the flow of electrons in a circuit and are connected in series.
• Insulation testers are used to check for leakage currents by applying a voltage and measuring the current.

Copper and its Alloys

• Copper and its alloys are used in telecommunications due to their ductility.
• Copper Beryllium is a strong and lightweight alloy with good electrical and thermal conductivity.
• Copper Zinc is harder than pure copper and is often used for connectors.
• Electrolytic Tough Pitch Copper (ETPC) is a highly conductive copper alloy with a conductivity of 100% according to the IACS.

Diodes

• Zener diodes allow current to flow in one direction up to a certain voltage and then allows current flow in both directions.
• Light-Emitting Diodes (LEDs) emit light when the depletion zone disappears, causing electrons and protons to cancel out.
• Laser Diodes emit highly focused laser light due to a central layer of aluminum, yttrium, and garnet in the p-n junction.

Polymers

• Polymers are used in telecommunications to insulate copper wires and prevent corrosion.

Fibre Optics

• Fibre Optics transmit electrical information by converting electrical current to light using a transmitter and back to current using a receiver.
• They offer safety, lightweight construction, and large bandwidth compared to copper cables.
• Fibre Optics consist of a core, cladding, and a protective layer.
• Single Mode Fibre Optics have a small core diameter, enabling the transmission of high-quality data but at a higher cost.
• Multimode Fibre Optics have a larger core diameter allowing multiple light paths and are cheaper than Single Mode Fibre Optics.

Multimode Fibre Optics

• Stepped Index Multimode Cables are the cheapest type with a core diameter of 62 micrometres, but have significant transmission losses.
• Graded Index Multimode Cables have a gradually decreasing refractive index from the core to the cladding, minimizing data loss and maximizing bandwidth.

Telecommunications Systems

• Analogue systems use a wide span of values.
• Plasma display technology uses noble gas in a vacuum chamber to create light from electrons and protons, offering high contrast and resolution but requiring high energy.
• Liquid Crystal Display (LCD) technology uses a backlight and shutters arranged on a grid, with liquid crystals rotating polarizers to produce different light intensities when subjected to voltage, offering less energy use but lower contrast.
• LED TV's use the same principle as LCD TV's but with LEDs for backlight instead of fluorescent tubes.

Telephony

• Fixed telephones utilize a loudspeaker, mouthpiece, earpiece, and main body to convert sound into electrical signals.
• Mobile phones utilize a network of cells, each with designated frequencies, for clear signal transmission.

Satellite Communication Systems

• Geostationary satellites remain at a fixed position above Earth, orbiting at an altitude of 35,785km, offering continuous coverage.
• Medium-Earth Orbit satellites orbit at altitudes between 2000km and 35,000km, commonly used for GPS systems.

Telecommunication Engineering

• Telecommunication engineers design and develop communication equipment and infrastructure.
• The field addresses health and safety concerns, including those related to optical fibre installation.
• Ethical and legal implications are of significant importance to the field of telecommunication engineering.