Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

LF: Effect of SID on 19.8 kHz

To: <[email protected]>
Subject: LF: Effect of SID on 19.8 kHz
From: "Markus Vester" <[email protected]>
Date: Sun, 22 Dec 2013 12:26:10 +0100
Authentication-results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of [email protected]) smtp.mail=[email protected]; dkim=fail [email protected]
Cc: <[email protected]>
Delivered-to: [email protected]
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1387711576; bh=TQxiz52DfKQfmH14A4IYBT4wF8DFTLRLE9eqT8Un2Rw=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=fUgRbKYdYDJz2OZDsOHu3RpOPifwc7RHB2G6ptnhqm0Y4LH1oEHMbod9qIuP+cB/e /zZ1djIYwHoFI+XF4nYXDGlrX5CugKIZCqAvFhk+2aOs7Sj619+cw+PE2MKGQHE1TW MDY/btYGA0SaKfCOjSP+yH+noptZ9Zy9CDu6OhT8=
Importance: Normal
Reply-to: [email protected]
Sender: [email protected]
It's interesting to observe the ripple pattern on a 19.8 kHz spectrogram, created by superposition of long and short path propagation from the Australian VLF transmitter NWC
 
During the European morning hours, the part of the short path which is lit by sunlight is gradually growing. With increasing ionisation, the "ceiling" of the waveguide comes down by a few km. We can deduce the path difference (long minus short) from the nulls of the spectrogram ripples. The diurnal shift is normally about two ripple periods (40 Hz here), corresponding to a total phase difference change of two wavelengths (30 km). The average Doppler velocity would be around -1 m/s.
 
Today around 8:10 an M-class solar flare occured, see attached gif from http://www.swpc.noaa.gov/rt_plots/xray_1m.html . In the NWC spectrogram, we find a remarkable effect of the additional D-layer depression, resulting in an extra path shortening of about 0.4 wavelength or 6 km.
 
Best 73,
Markus (DF6NM)
 

Attachment: Xray_1m_131222_1038.gif
Description: GIF image

Attachment: NWC_131222_1035.png
Description: PNG image

<Prev in Thread] Current Thread [Next in Thread>
  • LF: Effect of SID on 19.8 kHz, Markus Vester <=