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ENGINEERING, TE 2017 HSC 16 MC

Television programs that show high levels of activity often have lower picture quality.

This is because television signals are transmitted using

  1. digital modulation at low compression levels.
  2. digital modulation at high compression levels.
  3. analogue modulation at low compression levels.
  4. analogue modulation at high compression levels.
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`B`

Show Worked Solution
  • Modern television signals are transmitted using digital modulation, so the answer must be A or B.
  • The lower picture quality is the result of the TV being unable to decompress the highly compressed signal quickly.

`=>B`


♦♦ Mean mark 39%.

ENGINEERING, TE 2020 HSC 26b

Outline benefits of digital signal transmission.   (3 marks)

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Benefits of digital signal transmission include:

  • Immunity to transmission noise and interference (clearer signal)
  • Signal can be boosted or regenerated along the transmission path (reduced attenuation)
  • Can be encrypted to be kept secure and private
  • Signals can be processed and multiplexed (multiple messages can be sent along the same channel simultaneously)
  • Error detection and correction is possible
  • Cheaper than analogue transmission
  • Signal can be compressed
  • Signal can be stored and further processed
Show Worked Solution

Benefits of digital signal transmission include:

  • Immunity to transmission noise and interference (clearer signal)
  • Signal can be boosted or regenerated along the transmission path (reduced attenuation)
  • Can be encrypted to be kept secure and private
  • Signals can be processed and multiplexed (multiple messages can be sent along the same channel simultaneously)
  • Error detection and correction is possible
  • Cheaper than analogue transmission
  • Signal can be compressed
  • Signal can be stored and further processed

ENGINEERING, TE 2020 HSC 26c

Discuss methods for increasing the signal strength of a receiving antenna.   (3 marks)

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  • Amplification: Amplifies the sound, however this could include unwanted background noise.
  • Antenna tuning: The antenna can be tuned to the frequency of interest. This can be done by adjusting the length of the antenna, however this may not be practical in some scenarios.
  • Directional antenna can focus the signal to increase strength however misalignment could result in losing the signal entirely.
Show Worked Solution
  • Amplification: Amplifies the sound, however this could include unwanted background noise.
  • Antenna tuning: The antenna can be tuned to the frequency of interest. This can be done by adjusting the length of the antenna, however this may not be practical in some scenarios.
  • Directional antenna can focus the signal to increase strength however misalignment could result in losing the signal entirely.

Mean mark (c) 52%.