> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Alan Melia
> Sent: Thursday, July 08, 2010 12:27 AM
> To: [email protected]
> Subject: LF: Re: QRN
<snip
at 20kHz
> the morning an evening dips on the stations monitored by SID detectors are
> due to increased aborption.
Well, I would say that the differences of amplitude of VLF signals between
day and night are due the presence or absence of the D layer and that the
deep morning and evening dips are due to interferences between the ground
and the sky waves.
Jean-Louis F6AGR
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