[A-DX] Fwd: Shortwave Radiogram, 8-11 August 2019 / data @ 50 Hz

[Roger]

-------- Weitergeleitete Nachricht --------
Betreff:     Shortwave Radiogram, 8-11 August 2019
Datum:     Fri, 09 Aug 2019 09:44:57 +0000
Von:         admin <>
Last weekend, Shortwave Radiogram included a brief “hidden message”
during the closing music. It was in the BPSK63F mode, centered on 50 Hz.
At that very low audio frequency, it was not audible. I did not
publicize this message last week, because I was not sure that data at
such a low audio frequency would actually be pass through the WINB and
WRMI transmitters. When I established that the data was transmitted by
both stations, I publicized it in the @SWRadiogram Twitter account. A
few listeners were able to decode the BPSK63F. The BPSK63F is not as
robust as the MFSK modes we usually use, so it did sometimes fail during
fades. But it could work on a local AM (medium wave) station, where
fading is not generally an issue, coexisting inaudibly with the voice
and music programming. We’ll try this again in future shows.
Thanks to those of you who stated your preference on the line breaks at
65 characters. There is now definitely a consensus in favor of the
65-character breaks rather than “natural” line wrapping.

L'articolo Shortwave Radiogram, 8-11 August 2019 proviene da Bclnews.
https://www.bclnews.it/2019/08/09/shortwave-radiogram-8-11-august-2019/


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Hier  die entsprechende extrahierte  "versteckte Botschaft" im
Tiefbassbereich bei 50 Hz:
https://www.dropbox.com/s/9uzhw26d7fvmik4/2019-08-03_SWRG111_BPSK63F-50Hz.wav?dl=0

Mit einem Sennheiser HD599 ist allerdings sehr deutlich das
Tiefbass-Gebrodel  zu hören, dekodierbar in FLDIGI.

Wer nichts hören kann, dessen Anlage ist nicht Tiefbass-tauglich, was
Frequenzen unter 100 Hz betrifft.


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Zu Datensignalen im Tiefbassbereich noch eine kurze Notiz vom Slow Scan
Radio-Produzenten PA0ETE:

Am 16.03.2019 um 08:42 schrieb John Piek (ICT-translations):
> I have also experimented with such a signal on the internet stream
> recently. Because there audio works from 5 Hz, I had the data on 65 Hz
> and 32 Hz. With -20 or -30 dB this was virtually undetectable by ear,
> but depending on the other audio, data sometimes went completely off
> the rail. I could fix that with filtering on high pass at 100 Hz on
> the spoken audio, and although with spoken word in production I always
> use a 150 Hz high-pass (which most mixing tables and mic apps have as
> a standard), this extra 100 Hz filtering, although quite steep, still
> messed up the audio a bit. The amount of that was quite different,
> depending on different audio interfaces on the reception side, and
> some people reported this as being really annoying (especially one,
> who when I asked, used an expensive Bose speakersystem with an extra
> low bass speaker....)
> Hava a good weekend!
> 73 John

Ja, "really annoying"  so ein Datengedröhn, wenn man es hören kann. ;-)



roger