[Lowfer] MF Multipath Propagation

[Dexter McIntyre W4DEX]

For several nights Steve Dove ran his Grabulator II on NC Hi-Medfer
frequency of 1704.983 kHz.  Last night propagation was much better than
the night before.  At 0041 UT I snapped a shot from his page showing
what looks like two signals separated by about 0.2 Hz which lasted about
2 min.

Today Steve sent me two captures from last nights run.  One made at 0125
UT shows a normal fairly clean signal across the whole screen.  Another
capture made at 0319 shows a lot of what appears to be multipath with a
short period of dual path signal nearing 0.3 Hz shift.

I would like to hear some explanations as to what creates this shifted
frequency.

The three screen grabs are located at:

http://w4dex.com/argo/hi_medfer/nc_himedfer_by_stevedove_18jan04.htm

Dex