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I'm not at all an expert on propagation. So are you saying that
propagation of 60 kHz signals is via ionospheric skip? E or F layer? I didn't think the LUF ever got anywhere near 60 kHz at any time. Roy Lewallen, W7EL Paul Keinanen wrote: On Sat, 04 Oct 2003 18:06:23 -0700, Roy Lewallen wrote: At 60 kHz, there shouldn't be any difference between daytime and nighttime propagation. Certainly the ionosphere isn't involved. Roy Lewallen, W7EL Don't forget the daytime LF/MF attenuation in the D-layer, by preventing it from reaching the E-layer, which sets the LUF (Lowest Usable Frequency). At night, the D-layer disappears, thus, the signal can reflect from the E or F layer. At least the 77,5 kHz Maiflingen standard time transmitter in Germany is usable to about 2000 .. 2500 km from the transmitter during the night at least in the winter. However, during the summer nights, the D layer is in constant sunlight all night nearly 1000 km south of the arctic circle, which may explain the worse conditions during summer night, but of course the number of lightnings is also higher during the summer, increasing the band noise. Paul OH3LWR |
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