# Shared Flashcard Set

## Details

Telecommunications
Learning outcomes for Standard Grade Telecommunications
41
Physics
10/25/2009

Term
 How does the speed of sound compare with the speed of light? Give example.
Definition
 Speed of light is about 1,000,000 times more than the speed of sound.
Term
 Describe a method of measuring the speed of sound in air which uses the relationship between d, v and t.
Definition
 Two microphones attatched to a timer method.
Term
 Name one way of transmitting signals.
Definition
 Waves, ya retard!
Term
 Describe a wave in terms of frequency, wavelength, speed, energy (transfer) and amplitude.
Definition
 Frequency is number of waves produced per second. Wavelength is the length from crest to crest. Speed is distance travelled over time. Energy transfer is the amount of energy the wave holds. Amplitude is height from rest to crest.
Term
 Explain why f x lamda is the same as d / t for calculating the speed of waves.
Definition
 They both equal v.
Term
 Describe a method of sending a message using code.
Definition
 Morse code.
Term
 Transmitters and receivers are used for what?
Definition
 Transmitting and receiving waves.
Term
 State the name of a device which allows long range communication using wires between the transmitter and receiver.
Definition
 Phone, mongol.
Term
 What are the energy changes in a microphone and a loudspeaker?
Definition
 Sound to electrical, and vice versa.
Term
 State the devices in a telephone mouthpiece and an earpiece.
Definition
Term
 What is transmitted along the communicating wires during a telephone communication?
Definition
 An electrical signal.
Term
 Explain the pattern of an electrical signal in a telephone wire in terms of loudness and frequency.
Definition
 I don't have a clue.
Term
 What's the speed of sound in air, and a signal along a telephone cable?
Definition
 Sound in air - 340 m/sTelephone signal - 3 x 10 to the 8 m/s
Term
 What will the change in the wave be when it gets louder, and the frequency gets higher?
Definition
 Higher amplitude and higher pitch (waves more squashed together)
Term
 How do frequency and amplitude relate to sound?
Definition
 High frequency = high pitch, high amplitude = loud volume
Term
 WTF is an optical fibre?!
Definition
 A strand of glass.
Term
 What are optical fibres used for in telecommunications?
Definition
 Long distance phone calls, broadband etc.
Term
 What are the two main types of cables used to transmit information in telecommunication?
Definition
 Copper and Optical fibres. WOOT!
Term
 Why are optical fibres better than copper cables?
Definition
Term
 Light can be reflected. WTF is that supposed to mean?
Definition
 It gets bounced, ya noob.
Term
 What is the law of reflection?
Definition
 angle of reflection = angle of incidence.
Term
 What is the speed of a signal along an optical fibre?
Definition
 2 x 10 to the 8 m/s (this means copper cables are actually faster! but still crap.)
Term
 What are the six main parts of a radio receiver?? (also, what do they do?)
Definition
 ariel (gets the radio signals), tuner (selects one signal), decoder (removes carrier wave), amplifier (increases amplitude of wave), battery (powers amplifier), loudspeaker (turns signal into audio signal so you can hear it!)
Term
 Whats the general principle of radio transmission in terms of transmitter, carrier wave, amplitude modulation and receiver?
Definition
 Well..... change amplitude of carrier wave.
Term
 What are the 7 main parts of a television receiver? (yeah, just learn it.... even tho it sucks)
Definition
 ariel (picks up signals), tuner (selects one signal), audio decoder (demodulates audio), video decoder (demodulates video), audio/video amplifiers (increases amplitude of audio/video signal), loudspeaker (turns audio signal into sound so we can hear it), tv tube (turn electrical signal into light so we can see it)
Term
 What is the general principle of television transmission in terms of transmitter, carrier wave, modulation, video and audio receivers?
Definition
 Combine the audio and video signals and modulate the signal.
Term
 How is a picture produced on a tv in terms of line build-up?
Definition
 The electron gun scans across the 625 lines that make up a tv screen so quickly it appears like a picture.
Term
 How is a moving picture produced on a black and white tv?
Definition
 The electron gun scans across the tv screen and changes the brightness by altering the amount of electrons fired. The images are made so quickly that our eye cant keep up and sees it as a moving picture.
Term
 What are the three colours used in a colour tv?
Definition
 RGB, red, green, blue.
Term
 If you mix the three colours used on a colour tv, what do you get?
Definition
 WHITE!
Term
 Give three examples of long range communication which do not need cables between transmitter and receiver?
Definition
Term
 What carries energy between the transmitter and receiver in microwave, radio and tv telecommunication systems?
Definition
Term
 What is the speed of microwave, radio and tv signals through air?
Definition
 3 x 10 to the 8 m/s (aka the speed of light)
Term
 What properties of the transmitted radio waves allow us to identify the source transmitter?
Definition
 Energy...?
Term
 What are the differences in properties of radio bands?
Definition
 LW has good diffraction and travels far, MW is for both local and distant broadcasts, SW is for navigation and barely diffracts.
Term
 How does wavelength affect tv and radio reception in terms of diffraction?
Definition
 If a wave hits an obstacle and has to diffract, LW is going to diffract more than MW and thus is more likely to be recepted. This is also why it is easier to receive radio signals than tv signals.
Term
 Why are curved reflectors used?
Definition
 Because it is easy to focus all the signals on to one point.
Term
 Where are curved reflectors used in telecommunications?
Definition
 Well, thats what a satellite dish is, simpleton.
Term
 How does the height of a satellite affect the time it takes to orbit the earth?
Definition
 The higher a satellite is, the longer it takes to orbit the earth. (like the difference between running round a track in the outside lane instead on the inside lane)
Term
 What is geostationary orbit?
Definition
 Its when a satellite goes round the earth so that it stays above the same point all the time.
Term
 How does a tv signal get broadcast to another country?
Definition
 It is sent to a satellite which receives it and then transmits it down to the other country.
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