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Propagation map

Map reception paths from FT8, FT4, and WSPR decodes and estimate a lower bound on maximum usable frequency (MUF). The map uses decoder events, with no additional signal processing.

Build one

  1. Add FT8, FT4, or WSPR channels and a Propagation map.
  2. Connect each channel's events output to the map.
  3. Connect GPS position to position. For a fixed station, enter coordinates in the GPS node's Fixed tab.

The map also loads six hours of decoder-log history for connected channels when opened.

Read the layers

LayerDisplay
ActivityEstimated reflection points weighted by decode count and age
MUFEstimated MUF lower bound per Maidenhead square
PathsGreat-circle paths by station and band, newest first; off by default

A message must contain a Maidenhead locator to add a path. Reports, RRR, RR73, and 73 usually contribute no new location data.

The model divides each path into hops and estimates reflection points. A single-hop reflection point is the midpoint. Points are grouped into Maidenhead squares and lose half their weight per Half-life, adjustable from five minutes to twelve hours. The table ranks squares by activity.

Measured MUF

Receiving a signal proves its path supported that frequency at that time. The model scales it to a 3000 km reference hop:

MUF(3000) ≥ f × M(3000) / M(D / hops)

Here, f is received frequency, D is path length, and M is the obliquity factor (sec φ) for a thin reflecting layer over a spherical Earth. At a 300 km layer height, M(3000) is about 3.28. A single 3000 km hop reports the received frequency; shorter hops scale upward.

Interpret the result as a model-dependent lower bound:

  • Paths under 500 km count as activity but do not contribute to MUF.
  • Missing decodes on a band do not establish that the band was closed.
  • Layer height changes the estimate. Use 300 km for F2 or 110 km for sporadic-E modelling.
  • A result below a forecast does not by itself disprove that forecast.

Comparing against the ionosonde network

Enable Ionosondes for GIRO and INGV soundings through prop.kc2g.com. The server caches results for fifteen minutes.

The map shows station MUF(3000 km) and compares local estimates with an inverse-distance interpolation of sounding sites within 3000 km. The footer reports squares above the forecast and the median difference.

Feed failures are reported while local decodes remain visible. Disable Ionosondes to stop sounding requests; basemap requests are separate.