[time-nuts] reception of loran C from Sylt

Ole Stender Nielsen olstni at mail.tele.dk
Fri Aug 7 18:59:57 EDT 2015


Hello Ludwig,

I live about 280 km from Sylt, and receive the Loran-C transmitter with 
nice noise margin figures reported by the Stanford FS700. Presently, I 
use an untuned loop antenna to receive the signal, as described in a 
previous thread, but I have also used an E-field antenna. The nice 
figures did not come about without effort, though.

As Poul-Henning has pointed out already, switch-mode power supplies are 
a common source of noise. It's worth taking a look at the various power 
supplies, at the consumer electronics, the PC gear and the LED lamps in 
your house, one by one, to find out which of these that is particularly 
noisy, and perhaps the source of the annoying carrier close to 100 kHz. 
I found a power supply, for instance, that had the ability to wander 
around 59 - 61 kHz, which is not great when one wants to receive the MSF 
service at 60 kHz, too.
If you have a CRT monitor, the deflection circuitry may also play a 
trick. Previously, unwanted carriers sometimes originated from the 
harmonics of the deflection frequency in TV sets (N * 15625 Hz in 
Europe, and N * 15734.26...  Hz in the US), but as consumers turned to 
flat panel displays, this specific issue gradually disappeared. Another 
source of noise could be some Ethernet-over-power system in operation 
close to you, or perhaps there's some communication by the power company 
taking place through the power grid.

In order to get solid improvements of the noise level, my loop antenna 
and my E-field antenna eventually had to be located away from the mains 
cabling of my house. The reason is that any switching power electronics 
(yours, or your neighbor's!) will emit noise back to the mains, and the 
mains cabling will inevitably couple, inductively and/or capacitively, 
the noise to the reception antenna. Again, communication on the power 
lines may clutter the spectrum further. The required distance between 
your antenna and the mains cabling depends on the specific pool of 
switching power electronics in or close to your home, and on the 
specific layout of the mains cabling. Experiments will be needed to see 
how the noise level changes when you move the antenna around.

In my case the loop antenna ended up in the attic of my house, and the 
E-field antenna ended in a shed in a corner of my garden where there's 
the largest distance to my house and to the neighboring houses. The 
location and orientation of the loop antenna ensures good reception of 
Loran-C, even when my neighbor turns on his induction cooker (!)

Best regards
Ole

Den 07-08-2015 kl. 06:39 skrev Ludwig Puller:
> Subject: reception of loran C from Sylt
>
> Hi all,
> some time ago a gentlemen living only some hundred miles from Sylt
> reported in the net about loran C reception coming from Sylt. I could not
> find his report in the net. I want to talk to him about this subject. I
> live in Vienna/Austria and have a strong carrier close to 100 khz
> not knowing if it is house made or a transmission from somewhere.
> I live also from time to time in Hannover (north of germany) only
> about 400 km south of Sylt, where I could fire up my 2100F.
> Any experiance is wellcome.
> regards
> Ludwig
>
>
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