Date: Sun, 22 Mar 2015 23:02:56 +0100
From: Pieter-Tjerk de Boer <ptdeboer@cs.utwente.nl>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: eclipse observations on Twente WebSDR
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Hello Roelof and others,

At my location, the 189 kHz signals also had a dip before the peak, like
you describe.
The dip and peak are less pronounced (i.e., fewer dBs) here than the
numbers you mention, but that may be due to bandwidth differences; my
measurements were in about 400 Hz of bandwidth.

Could you have a look at the 216 kHz signal in your recording?
On my receiver, it had a dip of about 20 dB, and no peak, which I find
surprising.

I've added more detailed signal strength plots, and a map of the eclipse
timing, to my webpage ( http://wwwhome.cs.utwente.nl/~ptdeboer/ham/eclipse2015/ ).
It turns out the peak on 189 kHz is about 3.5 minutes earlier than on
207 kHz. This nicely matches the fact that the 207 kHz transmitter is in
the east of Iceland, while 189 kHz is in the west. On Iceland itself
the eclipse was about 5 minutes later in the east than in the west.
Where the radio paths cross the totality zone, the difference is about
3.5 minutes.
Also, the maximum signal strength lags the maximum eclipse by about 3
minutes.

73, Pieter-Tjerk, PA3FWM


On Sat, Mar 21, 2015 at 04:10:41PM +0100, roelof@ndb.demon.nl wrote:
> Hello Pieter-Tjerk,
> 
> At my location Iceland at 207 kHz is plagued by SNRT from Marrocco, 
> which overrides it at night and is also audible underneath Iceland 
> at daytime. Due to this co-channel interference, the carrier of 
> Radio Iceland is fading fast up and down a few dB (motorboating).
> 
> The transmitter on 187 kHz has a stable carrier here and at daytime 
> the level is - 101 dBm. 16 minutes before the eclipse the level 
> dropped to -117 dBm. This dip happened in the course of three 
> minutes.
> 
> After the dip the signal gradually increased to -80 dBm at the time 
> of eclipse. It stayed at that level for 3 minutes and than gradually 
> dropped to -101 dBm at 10:15 UTC.
> 
> The increase in signal strength was 21 dB.
> 
> 73,
> Roelof Bakker, pa0rdt
> Receiver: PERSEUS SDR
> Antenna: pa0rdt-Mini-Whip mounted 5 meter high.
> 
> 
>