| | 68 | In order to send signals as higher frequencies, we use a technique call modulation. We take the real part, I(t), of a signal and multiply it with a sine wave of the desired high frequency and the imaginary part, Q(t) with a cosine wave of that same frequency. |
| | 69 | |
| | 70 | S(t) = I(t) + Q(t)i -> I(t)*sin(wt) + Q(t)*cos(wt) |
| | 71 | |
| | 72 | Note how the resulting signal is always real, even if the original signal had an imaginary component. It is important to remember that even though complex/imaginary signals are useful for various reasons, they don't actually exist in the real world because... well, they are imaginary! |
| | 73 | |
| | 74 | [[Image()]] |
| | 75 | |
| | 76 | Example of a square wave modulating a sine wave of higher frequency. The square wave switches between 1 and -1 causing the sine wave the flip over and over again. |
| | 77 | |
