USCG NMC Morning Sign-On

This test pattern is transmitted daily at 1840 UTC by NMC, the US Coast Guard Communication Area Master Station, Pacific, in Pt. Reyes, California. The major limitation on reception at this distance isn't ionospheric fading as much as multipath, which can really smear the signal out. Note the tendency of white areas to fill in black ones, and for sudden transitions out of black to ghost many times. Pretty amazing.

NMC broadcasts a full schedule of East Pacific weather products on a number of well-documented frequencies in four large blocks starting at 0140, 0655, 1400, and 1840 UTC.