1. The problem statement, all variables and given/known data 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. 2. Relevant 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 3. 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.