wireless regulatory environment wireless regulatory environment
There is always a very long spectrum in the wireless environment, and different frequency bands have different functions.
- wireless medical telemetry service
- Low Interference Potential Devices (Low Interference Potential Devices)
- Media Body Area Network
Square wave: use Fourier series (sinusoidal waves are superimposed to form a rectangular wave with a 90-degree angle)
The first picture is a depressed sine wave cos(x)
The second picture is the superposition of 2 cute sine waves cos (x) +a.cos (3x)
The third picture is the superposition of 4 springing sine waves
The fourth picture is the superposition of 10 constipation sine waves
As the number of sine waves gradually increases, they will eventually superimpose into a standard rectangle. What do you understand from this?
(As long as you work hard, you can straighten any bends!)
As the superposition increases, the rising part of all the sine waves gradually makes the originally slowly increasing curve steeper, and the falling part of all the sine waves cancels out the part that continues to rise when it rises to the highest point, making it a horizontal line. A rectangle is superimposed in this way. But how many sine waves are added to form a standard 90-degree square wave? Unfortunately, to tell you, the answer is infinitely many. (God: Can I make you guess me?)
Insert here a webpage explaining Fourier series and transformation in simple terms
This is a diagram that can help us understand waves and frequencies (for details, please refer to the above website)
The specific mathematical content of Fourier transform
《Summer school session 2 {Fourier}》