Fitting and smoothing the noisy curve

The attached image shows lot of noise. How can I get smooth graph? I used different types of fittings like polynomial, spline, gaussian but none of them fitted it. The highest peak shows lots of smaller peaks that I don't want. How can I get similar type figure like image 2 (right side) from first image? I need only one highset peak as well as for sidelobe peak instead of multiples smaller peaks. I would really appreciate if you someone helps me.

Answer 1

[Sindar]

check out smoothdata and this guide