Tuesday, 5 December 2006

SVA Athens Meteo HF-Fax

Athens Meteo transmits on 4481 // 8105 kHz, ~0900z-1115z. The transmission program is the same found at NOAA's rfax publication, just add 15 minutes! A sample picture follows, copied on 4481 kHz:

4481kHz 0926z

Transmission of the above chart started at 0926z (11:26 local time). I must say I've cheated a little bit. Athens' transmission originally is a bit slanted, and not spectrally pure. A spurious tone just below 1500 kHz (the black frequency) interferes and messes the reception. The image is produced with corrected slant, and using an audio bandpass filter applied to the audio recording, to keep only the useful part of the audio spectrum. I decoded the image from the filtered audio file.

Here is a spectrogram of the original audio file:

You can see the spur just below 1000Hz. It seems to be a transmitter problem and not QRM.

Sometimes, prior and after the program session, voices and chat between staff can be heard. While I'm a SWL for some time, I haven't stumbled upon Athens Fax transmissions. So maybe it is a come-back after a silent period of time?

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