I wound this by hand. This took about one hour.
Yes, these ferrite antennas are a valid starting point, I would give them a try
I reprocessed the SAQ Grimeton Christmas Message this morning at the more standard Morse tone of 750 HZ.
The processed file "Grimeton SAQ Xmas Message 24th December 2023 750Hz.wav" is in mono at 8000 samples per second.
During the processing I realised that the Morse code can be seen in the raw data.
The processed file "Grimeton SAQ Xmas Message 24th December 2023 750Hz.wav" is in mono at 8000 samples per second.
During the processing I realised that the Morse code can be seen in the raw data.
There is a very faint CW at exactly 17000 Hz that is modulated and looks a bit like Morse code ????
So I expanded it as following image:-
Also noticed the small variations in the SAQ CW frequency whereas others (crystal or atomic clock controlled) do not vary. Also noticed that the SAQ CW never completely turns off, its still there between dots and dashes. They told us this happens in the explanation.
cc @fowlay
So I expanded it as following image:-
Also noticed the small variations in the SAQ CW frequency whereas others (crystal or atomic clock controlled) do not vary. Also noticed that the SAQ CW never completely turns off, its still there between dots and dashes. They told us this happens in the explanation.
cc @fowlay
There are many types of ferrite material, some for lower frequency some for very high frequency. For example 3F4 a very commonly used ferrite material is quite happy over 2 MHz. See datasheet attached.
This article by the famous Dallas Lankford also applies to VLF: https://www.okdxf.eu/lankford/MW And LW Noise Reducing Antennas II.pdf
Don't forget that "ground" must be good IOW not applicable in mountainous regions).
When interested in more, https://www.okdxf.eu/index.php/technika/80-antenarska-kolekce-dallase-lankforda
Those antennas require some real estate (garden). In apartment buildings the noise level is likely to be too high even for insensitive ferrite rod antennas.
Don't forget that "ground" must be good IOW not applicable in mountainous regions).
When interested in more, https://www.okdxf.eu/index.php/technika/80-antenarska-kolekce-dallase-lankforda
Those antennas require some real estate (garden). In apartment buildings the noise level is likely to be too high even for insensitive ferrite rod antennas.
Good. I suspected the extra antenna was non-functional and just for looks. I ordered a simpler unit which outputs pulses for decoding. WWVB varies power 17db and also does phase-shift keying. I am on the northern edge of it's coverage except at 0600utc. It may be received in France at that time. I am interested in the 60khz signal quality, I don't need to decode it. If I can receive it I will have a reference. And it probable that VLF will work as well.
@Aridace I read the paper on noise reducing MW antennas. It is very interesting - everything is symmetric and transformer coupled. The website is amazing a lot of work.
There is a paper about Common Mode Filters written by Siemens, maybe these types of filters might help antenna noise. Its just that a lot of problems in audio and electronics in general are unwanted common mode signals .
There is a paper about Common Mode Filters written by Siemens, maybe these types of filters might help antenna noise. Its just that a lot of problems in audio and electronics in general are unwanted common mode signals .
The effect of common mode filters depends on the impedances involved. With bad ground here (between 2m ground rods spaced 2m there's 140 (!) ohm) even 1k impedance (at 100 KHz) of the common mode filter wasn't enough. Hence the S/N improvement by fully symmetrical loop antennas and close to SWR= 1 feedline.
The original processed has some noise but sounds like telegraphy.
This new processed is not so clear. It sounds like a recording made underwater.
The first .wav file attached to #342 is SAQ reprocessed. The second file from a CW at 17000 Hz attached to #344 is not SAQ. It is just very close by and I'm interested to know what it is.
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The reprocessed SAQ file with Morse code is attached to #342. Also attached here again.
I’m not an RF guy, but…
I see a lot of parallel resonant circuits here for receivers, would there be any benefit in having a series resonant circuit and feeding it into a virtual earth on an op-amp? i.e. a short circuit at these VLF frequencies
Brian
I see a lot of parallel resonant circuits here for receivers, would there be any benefit in having a series resonant circuit and feeding it into a virtual earth on an op-amp? i.e. a short circuit at these VLF frequencies
Brian
17000 is not listed in the https://www.sigidwiki.com/wiki/Signal_Identification_Guide
There is an associated Discord server where people discuss signals. Perhaps you can inquire there
When you identify 17000 you can email your findings to the wiki admin
Is 17000 still active or does it just shadow 17200
As soon as I find my horizontal tuning coil, I'm building the 6U8 version of the VLF receiver - without the unnecessary parts...
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