Thanx for reply.
I don't Have access to any other product to compare the peaks
but i have found this article:http://www.tek.com/Measurement/App_Note ... 8815-2.pdf
(i also atached it)
This is an aplication note for Tektronix TDS1000 oscilloscopes.
it's told in section 1.23 page 22 that "the TDS
oscilloscopes correct the FFT magnitude output data by a factor of 1/CG, where CG is the coherent gain
of the window"
Also i have another question:
The FFT size can be changed, if size is bigger or less than
scope memory , which part of data is choosed for FFT?