Its Latin for "and others" 👍
-apparently "et al. should always be written in italics, with a full stop at the end of al" !!
-"abbreviation for et alia: and others. It is used in formal writing to avoid a long list of names of people who have written something together"
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I was hoping to go to an outdoors location far from power lines and induction cookers to capture the SAQ Grimeton signal. This was cancelled because of an unfavourable weather forecast this morning. Instead I used by balcony antenna, getting once more a somewhat noisy result: https://privat.bahnhof.se/wb748077/radio/2024-06-30-grimeton/
A much better SAQ reception this morning.
Only this week I realised that far end of my 25 m antenna must be connected to Ground so that the antenna makes one very big closed circuit loop (with current flowing back through the Ground. Same idea as your backpack antenna. The signal is much stronger this way.
But the closed 25m loop shorts out the primary of the receiver preamp transformer. It works fine but takes out any resonance that the receiver preamp was intended to have. Not sure how to fix the resonance for a very big loop like this?
Only this week I realised that far end of my 25 m antenna must be connected to Ground so that the antenna makes one very big closed circuit loop (with current flowing back through the Ground. Same idea as your backpack antenna. The signal is much stronger this way.
But the closed 25m loop shorts out the primary of the receiver preamp transformer. It works fine but takes out any resonance that the receiver preamp was intended to have. Not sure how to fix the resonance for a very big loop like this?
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Not a noisy result, just check your processing. I reprocessed your raw wav file and attach it and screenshot. OK its 760 not 900 duh.
Attachments
Outside antenna I used 30th June 2024 to record SAQ Grimeton VLF transmission at 17.2 kHz.
Notice that the far end of the Antenna is connected to Ground.
The entire Antenna forms one very big loop 25m length 3m height. The loop circuit is completed by the Ground connections.
Notice that the far end of the Antenna is connected to Ground.
The entire Antenna forms one very big loop 25m length 3m height. The loop circuit is completed by the Ground connections.
The Receiver is a typical sound preamplifier and uses the Analog Devices AD8397 Opamp to amplify the received signal which is in the audible sound spectrum. Output from the preamp is connected to a high quality PC soundcard and processed by Audacity. Hope that helps.
SAQ Grimeton Sweden transmits at 17.2 kHz yes 17.2 kHz. SAQ Grimetion is a World Heritage site in Sweden !!
See also:-
Alexanderson Association Sweden
Christmas Eve 2023 Transmission SAQ Grimeton Sweden
You are right .. I think now I could have made my bandpass filtering more narrow. If anyone wonders about how a 17200 Hz signal can be made readily audible, check here: https://alexander.n.se/en/the-radio-station-saq-grimeton/lyssna-pa-saq/ (look for "Reception using an audio editor")