FWIW, the signal is no longer modulated at 1Am PST. The carrier is at
135.95 when I use the sync mode to lock onto it. The signal is just as
strong, simply not modulated.

wrote:
www.lazygranch.com/sound/shortwave/136khz.wav
Recorded in the SF bay area. I got the demo of skysweeper to decode it
as FSK, though not terribly interesting data.

Any idea of the source of this signal?