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 Post subject: Receiving VLF SAQ Grimeton with simple equipment at home
PostPosted: Feb Mon 12, 2018 7:53 pm 
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Joined: Apr Mon 18, 2016 11:03 pm
Posts: 9
Location: Berlin, Germany
The traditional transmission with the Alexanderson 200 kW alternator on VLF 17.2 kHz from Grimeton, Sweden, can be received with ferrite antenna and regenerativ audion technique. Quality is low, distance is 500 km to Berlin, Germany. But it is possible. https://www.youtube.com/watch?v=I0luIo78fIg


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 Post subject: Re: Receiving VLF SAQ Grimeton with simple equipment at home
PostPosted: Feb Tue 13, 2018 4:05 am 
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Joined: Jul Thu 29, 2010 5:35 am
Posts: 884
Location: Simonton, Texas
Talk about digging it out of the noise. Impressive!

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 Post subject: Re: Receiving VLF SAQ Grimeton with simple equipment at home
PostPosted: Feb Tue 13, 2018 10:06 pm 
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Joined: Apr Mon 18, 2016 11:03 pm
Posts: 9
Location: Berlin, Germany
If bandwidth is too high or too small the signal to noise ratio decreases. As shown in a diagram in the video: to correctly detect the morse signals you need a higher bandwith for a short "dit" than for a long "da". About the middle of both is therefore the best.

The resonant circuit itself and the position of the feedback coil determine the bandwith. In the realtime FFT spectrum you can watch a wide signal resulting from feedback just bevore oscillation occours (screenshot in video). In addition the smaller signal from morse patterns sits than at 17.2 kHz on top. I hope this description is understandable.


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