how can I get the hybird signal mixed in frequency domain seperated?

In the latest matlab version R2018a, I found a function of signal processing emd, we know that the emd function is already applied from extra source or package, but it is first time to appear in the signal processing toolbox, I am pretty happy to see that.Emd is design to seperate signals to get imfs, which concentrates to time domain hybrid signals. But I want to know is there any method to get mixed signals seperated, whose imfs are mixed in frequency domain? </matlabcentral/answers/uploaded_files/111158/QFM_4FSK.jpg>

[liu lin]

this is a time frequency distribution from a mixed signal, which consists of frank and 4fsk