[A-DX] VOA Radiogram, 23-24 January 2016, multipath, Olivia-64-2K: 100 %, MFSK-32: 10%

[Roger]

Am 24.01.2016 um 00:48 schrieb VOA Radiogram:
>
> Thanks Roger!     With the good signal into Europe today, 800 Hz was 
> sufficient.
>
> I am in the skip zone for 17580 and had this interesting experience.  
> Try decoding from this audio ....
>
> https://t.co/K5YWNETXOm
>

Oh, "wonderful" multipath sound, such I have not yet heard with digital 
signals.  I think, Olivia 64-2000 has, compared with the tones of 
MFSK32, a better pulse shape.
The larger signal width (2000 Hz) enables a better *separation* between 
the signs.
Maybe, the OLIVIA-combination of more audio tones + higher signal width 
is the reason for the excellent multipath performance.
Here are both sound-examples in visual comparison - MFSK32-signs over 
multipath extremly blurred:

http://www.rhci-online.net/radiogram/VoA_Radiogram_2016-01-23.htm#multipath


https://en.wikipedia.org/wiki/Olivia_MFSK
====>
"....At a given time only one of those 32 tones is being sent. The 
demodulator measures the amplitudes of all the 32 possible tones (using 
a Fourier transform ) and (knowing that only one of those 32 could have 
been sent) picks up the tone with the highest amplitude...."


roger