Hello I am finding it a bit difficult to comprehend what the author of a famous text book has written about TV signal band width. Here is the excerpt from his book. Could any of you please explain what exactly he means? I dont get why the required bandwidth is around 5.5 MHz. "Another example of a nonperiodic composite signal is the signal received by an old-fashioned analog blackand- white TV. A TV screen is made up of pixels. If we assume a resolution of 525 × 700, we have 367,500 pixels per screen. If we scan the screen 30 times per second, this is 367,500 × 30 = 11,025,000 pixels per second. The worst-case scenario is alternating black and white pixels. We can send 2 pixels per cycle. Therefore, we need 11,025,000 / 2 = 5,512,500 cycles per second, or Hz. The bandwidth needed is 5.5125 MHz." When I reached AC circuits and its applications, I stumbled upon the above quoted paragraph and this doubt started bothering me since then. I clearly understood the logic behind 11,025,000 pixels per second and since a cycle can have two pixels 5,512,500 cycles per second or 5.5125 MHz. So, if I have understood correctly any signal with a frequency exceeding 5.5125 or let us say 6 MHz can theoretically contain all the information required for the TV transmission in the worst case scenario. Now, let me mention an example. North American channel 2 occupies the spectrum from 54 MHz to 60 MHz. A bandwidth of 6 MHz. My question is, provided that any frequency more than 6 MHz can contain the all information in the TV transmission, why cant Channel 2 use a particular frequency above 6MHz, say 57 MHz, instead of using the spectrum from 54 to 60 MHz? I understand from the ebook part of AAC that a modulated AC signal can have a number of harmonics and instaead of a single precise frequency it will be a band of frequencies and all. But I dont think that the explanation in the excerpt is related to harmonics and all but rather the to the information to be carried by the signal at the wost case.