[Lowfer] 18 kHz TACAMO?

[Dexter McIntyre W4DEX]

Are these brief transmissions on 18 kHz TACAMO?

https://www.dropbox.com/s/oxc1jxuqcc4kmwq/18khz_2020ut_16feb18.jpg?dl=0

I've been plotting 18.3, 21.4 and 24 kHz the past several days watching
watching the day/night changes.

Here's this morning's NAA sunrise dip:

https://www.dropbox.com/s/sr8u506c9zbn1o1/NAA_sunrise_dip.jpg?dl=0

I don't know why my current setup has so much rolloff above 24 kHz.

Dex