Pspice simulation for conducted emission measurement

Hii,

We are trying use Pspice to measure conducted emission from DC-DC convertor(Pri-Layout simulation). So can you please provide information about how to convert voltage to dBuV and frequeny in log scale if we have transient simulation plot. I have used fourier transform and after that i have change x axis scale from leanear to log but results are not as per expecations.

Also let me know if you have some modles which we can directly use for conducted and radiated emission.