Smooth a time serie not afectig max/minimun data?

Hello, I'm trying to find a way to smooth the data without afecting the max/min values of the time serie,

like generate/fitting a sinusoidal serie in where values at the edges (orange and yellow line) will no be affected by the method, I will apreciate any suggestion, thaks.

Answer 1

[Star Strider]

See if the Signal Processing Toolbox envelope function will do what you want. Choose the 'peak' option, and experiment with the 'np' argument to get the result you want.