More conditions

[HB9DQM]

See also the discussion here:

Spotter maximum distance

I guess the issue is where to obtain accurate data on callsign location from, in order to have a universal solution that works for callsigns worldwide and regardless of the spot source. QRZ.com comes to mind with their API, but based on a recent inquiry to their staff about bulk lookups (Trigger "QRZ.COM entry exists" for callsign pse? - #4 by HB9DQM) I don’t think this would work in practice at HamAlert’s scale. Related: