This morning the propagation skip shortened a little and I was able to receive a weak signal from the WINB combo signal. The System Evaluation screen (Attachment 1) shows that the DRM portion of the signal has a higher amplitude than the Data side. This is different from the transmissions earlier in the spring when the 15670 kHz spectrum looked the opposite with the Data portion at a higher level ( See thread: DRM WINB 15670 Khz message #44 attachment 2).
Attachment 2 (below) shows a recent view of the received spectrum from a KiwiSDR web receiver. The amplitude (A) of the datacasting portion is about 3dB lower than the DRM side. In addition a new "Guard Band" (B) has been introduced.
These changes are probably meant to reduce interference to the DRM signal by the datacasting component.
According to Antonio's blog http://i56578-swl.blogspot.com/2018/...rm-single.html
the datacasting signal appears to be OFDM (Orthogonal Frequency Division Multiplex) "that is not sending data but just an unmodulated (maybe) OFDM waveform".
This leads me to speculate, for what it's worth, that these relative low power WINB combo transmissions are primarily as a "proof of concept" to test the data simulcast configuration.
The lessons learned from these broadcasts, I continue to speculate, will probably be put to use with the new WBCQ Super station that is being built in Monticello Maine. The FCC filing documents indicate that there is a relationship with the new station and WINB.