In real life we have to deal with different signals. The ways of processing signals are very complicated. For example, for sound signal, our ears receive sound and our brain actually do Fourier transform to give us the magnitude of sound. The real signals in life are random. Unlike what we do Fourier transform in mathematics class by using the integration formula for simple signals, our brain actually did it by heavily digital computation. That's also a reason why we need to sleep everyday to let our brain rest.
As I have mentioned, the most interesting kind of signals is random signal. However, when we start to understand the behaviors of signals, we start with periodic signals. Because periodic signals are simple in mathematics. That is the purpose of learning periodic signals. It doesn't mean human like listening periodic sound or watching periodic video.
Some people obviously misunderstood this purpose. They used periodic signal to construct TV advertisement. They thought periodic signals which have a characteristic of repeating itself may give customers a deeper impression. Their idea was as same as Adolf Hitler's. Hitler believed a lie became true when repeating 1000 times. Maybe he is the first man who loves periodic signals.
In year 2008, a PRC brand HengYuanXiang broadcast its advertisement during Chinese New Year. After watching it, most people dislike this advertisement. I watched it on my computer. My first impression was "Oh, did my computer get virus?"!
As I have mentioned, the most interesting kind of signals is random signal. However, when we start to understand the behaviors of signals, we start with periodic signals. Because periodic signals are simple in mathematics. That is the purpose of learning periodic signals. It doesn't mean human like listening periodic sound or watching periodic video.
Some people obviously misunderstood this purpose. They used periodic signal to construct TV advertisement. They thought periodic signals which have a characteristic of repeating itself may give customers a deeper impression. Their idea was as same as Adolf Hitler's. Hitler believed a lie became true when repeating 1000 times. Maybe he is the first man who loves periodic signals.
In year 2008, a PRC brand HengYuanXiang broadcast its advertisement during Chinese New Year. After watching it, most people dislike this advertisement. I watched it on my computer. My first impression was "Oh, did my computer get virus?"!
(This is that terrible advertisement below.)
In Science or Engineering, people invent simple model like periodic signal or simple harmonic motion, because simple models are easy to study. Then a complex model can be made by constructing many simple models in some certain ways. It is the same in real life. When we start to learn something new, we will always start with something simple. It does not mean simple things or simple ways really work in all situations. In fact, methods which work for complex situations are also complex. Life is not that simple to analyze.
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