Bearing was 78/258 deg +/- 4, NWC is on 82.4 deg
and the GC paths are 13650km and 26380km, difference
is 12730 km along the ground, or 12810 at mid height
of Earth-Ionosphere waveguide.  Resulting interference
pattern would have nulls at 23.4Hz intervals.

Signal present in N/S loop, rather weaker, no significant
interference pattern, the pattern is seen only in the
E/W loop.
--
Paul Nicholson
--