You Can't FIX what Ain't There

It's no secret that WQ6X base operations utilize a bevy of external auditor filter units, in addition to the Yaesu FT-1000mp's built-in e-DSP facility.  

These units provide everything from NR (Noise Reduction), MNF (Manual Notch Filtering) and ANF (Auto Notch Filtering), audio AGC & overall bandpass contouring.

Properly adjusted, these filters can literally "PoP" signals above the noise and CRUD Level.  Because of their "binary nature",
Cw signals are the most easily boosted
with this kind of filter arrangement.  

Unfortunately,  no amount of audio processing can counteract the effects
of fading and poor propagation.

With the JPS NIR-12 DSP unit the DYN-Peak function raises the threshold a signal must reach in order to pass thru the filter.  

This approach essentially prevents low-level noise from leaking thru to the mixer or headphones. 
When signal levels are barely above that noise-level, those weak signals will be blocked as well. 
Sometimes switching from a HORIZ to VERT antenna configuration can noticeably reduce signal-fading.  

Sometimes a pre-amp in the receiver front-end can help, altho recognize that atmospheric noise is amplified along with the weak signals.  Alternately, switching the receiver to a different AGC setting can sometimes balance things out.  One of the advantages to running RTTY is that amazingly,
some decoder software can make sense out of audio tones barely audible in the headphones.

Bottom-Line:
No matter how effective the filters and DSP units are, if the signals aren't first somehow
jumping out of the void, there will be nothing to filter.

IF IT AINT THERE, THERE IS NOTHING TO FIX.