Hi Andy, I am afraid I have no real knowledge of Magetometers, other than
contact for help for people who have wanted to build them. I believe that
the Ap and Kp indexes (indicies ??) are a measure of the changes of the
earth field due to interaction with solar disturbances. I am not sure
whether the field is measured at ground level or not.

The other complication is that the major changes do no correlate directly
with propagation conditions but I do believe that it may be possible to get
up to 24 hours notice of a possible collapse in good conditions........a
sort of negative forecast. I'm still working on that one.

I will now go and read the gen on the sites quoted by Dick and see if I can
learn something too.

Cheers de Alan G3NYK
[email protected]