Exploring TV Sound & Picture Quality: Answering Your Questions

[Astar]

Homework Statement

I was given these two questions to answer regarding TV:
1) Explain why there is a need for two sound carrier frequencies.
2)Explain why you still get good sound quality reception during a thunderstorm but picture quality declines.

Homework Equations

I was given this information within the question

Australian TV broadcast standards:
Vision Carrier - 1.25 MHz above lower edge of channel
Vision Modulation - negative AM
Lines per picture - 625 interlaced 2:1
Line freqeuncy - 15625 Hz
Primary Sound Carrier - 5.5MHz above vision carrier
Secondary sound carrier - 242.1875kHz above primary sound carrier
sound modulation - FM

The Attempt at a Solution

1) The only thing I can think is so two sound waves can be played at the one time. For example: like having a person speaking with background music playing also.

2)I think it has something to do with picture being AM and sound being FM. I know that AM modulation is susceptible to noise. FM has less noise as a limiting circuit keepts the amplitude a near constant. The noise could explain the decline in sound quality reception...

I'm pretty stuck here. Any help would be greatly appreciated.

 

[anathema]

I would be happy to help you with your questions regarding TV sound carrier frequencies.

1) The need for two sound carrier frequencies lies in the fact that TV signals are transmitted in a specific frequency range known as a channel. This channel has a limited bandwidth and can only accommodate a certain amount of information. In order to transmit both video and audio signals within this limited bandwidth, two separate carrier frequencies are used. This allows for the simultaneous transmission of two different signals, such as a person speaking and background music, without interference or distortion.

2) During a thunderstorm, the atmosphere becomes charged with electricity, which can affect the quality of the TV signal being received. The picture quality may decline because it is transmitted using AM modulation, which is more susceptible to noise. However, the sound quality may still remain good because it is transmitted using FM modulation, which has a limiting circuit to keep the amplitude near constant and reduce the impact of noise. This is why you may experience a decline in picture quality but still be able to hear the sound clearly during a thunderstorm.

I hope this helps to clarify the reasons for the use of two sound carrier frequencies and the difference in sound and picture quality during a thunderstorm. Let me know if you have any further questions.