[digitalradio] Re: Recent MFSK16 DX
--- In digitalradio@yahoogroups.com, "Graham" wrote: > but with the stability of modern rigs I dont see why the > original mfsk should not make a come back ? The only time I had trouble with MFSK16 and frequency drift was when I was using the Elecraft K-2 radio with its 100W amplifier, and before installing a frequency stability mod they developed. Never had any trouble after that.
[digitalradio] Re: Recent MFSK16 DX
--- In digitalradio@yahoogroups.com, "Vojtech Bubnik" wrote: > > > In a simple shoot out between olivia 250 x8 and msfk16 , olivia > > stopped decoding whilst mfsk was still at 100% ... thought that was > > not supposed to happen ? > > Hi Graham. > > I am certainly not surprised and it confirms my Gaussian noise tests. > Olivia trades sensitivity for automatic tuning. MFSK16's convolution > coding provides for high sensitivity, but does not give sharp enough > indicator, whether the data is valid. Basically the Hammond distance > of the code is too low to give reliable indicator. Olivia uses Welsh > block coding, which provides good data validity indicator, but has not > as high coding gain as convolution codes. > > For explanation of coding gain, see the excellent article from g3ruh > http://www.amsat.org/amsat/articles/g3ruh/105.html > > I believe the perfect weak signal mode for HAM radio is yet to be > designed with easy tuning of Olivia and high sensitivity of MFSK16, > combining both convolution and block codes. Maybe overlying MFSK16 > with Reed-Solomon block code and running multiple MFSK16 decoders with > half tone spacing will do the trick. > > 73, Vojtech OK1IAK > The other thing was the initial test was mt63/500 ~ olivia 250 x 8 , MT dident do very well, so ended up with mfsk .. the single tone is handy as well , as many lf stns cannot handle linear modes like psk .. but with the stability of modern rigs I dont see why the original mfsk should not make a come back ? G ..
[digitalradio] Re: Recent MFSK16 DX
> In a simple shoot out between olivia 250 x8 and msfk16 , olivia > stopped decoding whilst mfsk was still at 100% ... thought that was > not supposed to happen ? Hi Graham. I am certainly not surprised and it confirms my Gaussian noise tests. Olivia trades sensitivity for automatic tuning. MFSK16's convolution coding provides for high sensitivity, but does not give sharp enough indicator, whether the data is valid. Basically the Hammond distance of the code is too low to give reliable indicator. Olivia uses Welsh block coding, which provides good data validity indicator, but has not as high coding gain as convolution codes. For explanation of coding gain, see the excellent article from g3ruh http://www.amsat.org/amsat/articles/g3ruh/105.html I believe the perfect weak signal mode for HAM radio is yet to be designed with easy tuning of Olivia and high sensitivity of MFSK16, combining both convolution and block codes. Maybe overlying MFSK16 with Reed-Solomon block code and running multiple MFSK16 decoders with half tone spacing will do the trick. 73, Vojtech OK1IAK
[digitalradio] Re: Recent MFSK16 DX
In a simple shoot out between olivia 250 x8 and msfk16 , olivia stopped decoding whilst mfsk was still at 100% ... thought that was not supposed to happen ? G .. --- In digitalradio@yahoogroups.com, "Andrew O'Brien" wrote: > > IW7DGY 10140.3 ES1HJ/QRPMFSK16 - 599 > 1830 10 Feb > PU2PTH-@7037.4 PU2PTH CQ MFSK16 > 2108 08 Feb > K4GST 18101.0 PZ5RA MFSK16 > 1709 08 Feb > N2ZN 18101.0 PZ5RAMFSK16 Ramon > 1657 08 Feb > ON3LX 3583.0 DJ2CVJN29WN<>JO64EI Tnx mfsk16 QSO > 1644 27 Jan > G0UZP 14073.2 VA7XXmfsk16 Pat gud op > 1425 19 Jan > OZ1PMX 3583.4 N4WI MFSK16 1200hz CQ > 0441 09 Jan >
