[A-DX] [dxld] VOA Radiogram digital text and images this weekend

Roger
Mi Jul 3 21:57:42 CEST 2013


Am 30.06.2013 15:44, schrieb Walter Salmaniw:
> Interesting, Roger.  I too wondered why I was having trouble 
> demodulating the signal.  It wasn't too weak, and yet even the MFSK 16 
> and 32 modes had lots of errors, and the digital images, absolutely 
> nothing.  Perhaps it wasn't just the propagation this week?  73,  Walt 
> Salmaniw, Victoria, BC
=======================================================
Hello Walter
On Sunday evening I had also tried again: 15670 kHz from 19.30-20.00z.
In the beginning there were short interrupts at the broadcast and at the 
end of the program the AM-Modukation sounded pretty awful .....
I think once, the old shortwave transmitter comes  to its limits with 
the digital broadcasts....
Narrow-band  emission are still ok ..
But the DRM-related emissions in DigiPal probably require a 
digital-capable transmitter newer design .....

During test receptions in Digipal (14.233 kHz) between a russian and a 
french amateur radio operator I had SNR values of 17db and more ....
I think these use modern SDR transceiver.
http://www.rhci-online.de/130701002325-Clip.jpg
http://www.rhci-online.de/130630223309-Clip.jpg
You can also request again  the missing data packets of the image of the 
first Passage..... awesome          (as a radio amateur with a 
transmitter........)

The radiogram-broadcasts of the VoA are quite interesting, a bit of a 
challenge - but where is the practical benefit in the future?
Program schedules, program notes ... ok .... but it need not necessarily 
be to transfer small and colorful images, wasting airtime ....
Such a fun thing radio amateurs can allow .... ;-)
http://www.rhci-online.de/130701000023-Clip.jpg
http://www.rhci-online.de/130701003621-Clip.jpg

73+55 roger