[A-DX] VOA Radiogram, 23-24 January 2016

So Jan 24 00:09:05 CET 2016

Am 22.01.2016 um 11:14 schrieb VOA Radiogram:
> Hello friends,
> last weekend's long transmission of Olivia 64-2000 was very 
> interesting. It did result in some successful decodes under difficult 
> conditions. You can see some examples here ...
> http://voaradiogram.net/post/137804494562/olivia-64-2000-noise-prevails-over-local-noise
> http://voaradiogram.net/post/137594112122/olivia-64-2000-from-north-carolina-decodes-in
> One thing I discovered is that, when receiving and decoding Olivia 
> 64-2000, it is important that the receiver bandwidth be wide enough to 
> include all of the data, which extends to 2500 Hz above and below the 
> carrier frequency. Otherwise, you cannot take advantage of all the 
> redundancy built in to the Olivia 64-2000 mode.
> Those of you who can record the audio using an SDR receiver can 
> experiment with various bandwidths, shape factors, AM versus SSB, etc.
> Anyway, last weekend's Olivia 64-2000 was so much fun that we'll 
> include one news item in that mode this weekend, in addition to our 
> usual MFSK32.
> ..........................I hope you can tune in and write in this 
> weekend.Kim Andrew Elliott
> Producer and Presenter
> VOA Radiogram


This time I checked the redundancy of Olivia-64-2K.  I put a sharp 
digital filter with SDR software in the USB-side. The bandpass I had 
reduced to the limit of an error-free decoding.
The minimum width of a 100% decoding is 800 Hz. (+/- 400 Hz at 1500 Hz 
center)   800 Hz  contain 100% of the information, at 2000 Hz total 
signal width - an incredible redundancy.
Olivia-64-2K is like a turtle, slow but very well protected. ;-)