My first decent fix with KiwiSDR TDoA mode

I finally got a good fix on a station with the KiwiSDR TDoA extension.  It's tricky, but for a system available to the public, it works amazingly well.  The instructions that are given from the "Help" button are accurate. That's how you do it.  The secret is indeed to use the minimum possible passband in IQ mode, and to pick relatively close receivers.

Here's a plot of the French 2-megawatt LW time station, made with three receivers. This band is groundwave propagation, with fewer variables than you get with skywave.  The signal is very steady, and comes from a known location, which we see marked by the "TDF" label.  The fix given by the Kiwi system nails the longitude right on, and only misses the latitude by about 30 arc-minutes to the north. That's pretty good.  It's possible that more receivers would have refined the plot further.

Anyway, it works.