Medium Wave Offset Atlas - all 10kHz channels, 24 hours

Nils Schiffhauer <DK8OK@...>

Hi - with the new Elad FDM-S3 and its OCXO/GNSS-stabilized clock, I did a 24h recording of the whole medium wave band on January 19, 2021 in Northern Germany. Free software SDRC V3 enabled me to make up a spectrogram of each channel within a window of 50Hz width, and at a frequency raster of 10kHz. You can easily see:

* sign-on/sign-off
* fade-in/fade-out
* accurate and stable frequency offset over full 24h down to a millihertz
* frequency control of the transmitter’s oscillator (stable, drift, sinus, sawtooth …)
* propagational effects (doppler, scatter …)

The format is PDF, DIN-A4, landscape, resolution 300dpi. This allows you to zoom to a factor of about 400% to search for details and better read out of the time/frequency scale. It weighs 559MB. You can download it, and open it with your PDF reader (you can also point your mouse cursor onto the link, click right mouse key, and choose “Save under …”). Leafing from one page to another gives an interesting overview.

Yes, a similar Atlas showing a raster of 9kHz is under way and will be published in due time. It is also planned to publish a general article about the background, about what to do with such a tool, and how to do this by yourself.

I am sure that it will open some new horizons on Medium Wave DXing, including accurate offsets over up to 24h.

An example of how having received even Hawaii at my location, complements the blog entry at:

73 Nils, DK8OK


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