TDoA code update

The TDoA code now does not explicitly use gnuplot any more. All plotting is done in octave. This will it make easier to extend the code (work in progress).

Recently some interesting signals have been independently observed by several people, see, e.g., tweet. These are frequency hopping signals.

Tuning a KiwiSDR to 7812 kHz two of the signal fit into its passband. Below are TDoA maps for these signals. Note that these maps are likely biased by the fact that some of the KiwiSDRs might receive the ground-wave signal and others a sky-wave signal.

TDoA maps

TDoA cross correlations

TDoA maps

TDoA cross corrlelations