Problem: sampling 50MHz signal at different rate

[ganeshkumarsw]

Here with I have attached dsl files, which holds the sampling of 50Mhz SPI CLK signal with setting of 16M samples @100MHz, 200MHz and 400MHz, its quite interesting to know that each file measures different SPI clock rate but at least @200mhz works fine but even then it varies in duty cycle from 50% to 75%, its weird behaviour.

I feel the hardware is stable enough till 25MHz signal beyond that its not promising, if you have different opinion, kindly share.

For the sake of attachment I have renamed the file to png, kindly save and rename it to .dsl

Is it a firmware issue or software issue?