Just to clarify,I mean discrete signals,more precisely 16bit PCM.Building sinewave sweep out of sinewaves? That probably sounds very confusing,let me explain.
We all know every signal can be deconstructed into individual sine waves,so the idea of constructing sinewave sweep from sinewaves might seem stupid,why would anybody need multiple sinewaves to construct sinewave sweep? Sinewave sweep is a sinewave! You cant deconstruct sinewave into more sinewaves... the problem with that is its wrong.
The key source of this confusion and also essential point of this question is amplitude,frequency & phase.Every signal can be deconstructed into sinewaves except constant amplitude,constant frequency,constant phase sinewave.The moment we start changing any of these three,the resulting signal will begin to be able to be deconstructed into multiple constant amplitude,frequency & phase sinewaves.
What we call sinewave sweep is at no point in time just single sinewave.If we have -6db constant amplitude sinewave sweep from 5 to 10 KHz in 1 second long signal at 40 KHz samplerate and 16bit depth with no dithering,how many constant amplitude,frequency and phase sinewaves we would need to put together to recreate the sweep?