Vojtech, Thank you for figuring this out.
I had thought that the mode ID was sent in the mode, and that all modes were decoded in parallel to see which one resulted in the ECC-protected key codeword. The advantage of senfing the mode ID using the mode itseld is that propagation characteristics that favor one mode over another will not cause failure to ID or the converse (copy of ID but failure to copy the actual transmission). All my questions had been with this belief in mind. 73, Leigh/WA5ZNU On Wed, 4 Apr 2007 8:24 pm, Vojtech Bubnik wrote: > Hi Patrick. On Wed, 4 Apr 2007 8:24 pm, Vojtech Bubnik wrote: > Hi Patrick. > >> >you send a heavily FEC protected keyword in the desired mode. >> >you do a parallel decode of all modes, de-FEC all and look which one >> >matches the the codeword ? >> Yes it is. But it is not only done for one frequency, it is done for > all frequencies in the band. > > I played with MultiPSK and listened to the generated RS sequence. In > my opinion it is always the same modulation. According to my ears and > spectrogram it seems to be some kind of MFSK modulation, always the > same number of tones and symbol speed. > > Please correct me, but I think there is a misunderstanding on the > list. I suppose that the RS ID is very similar to Olivia, there are > three differences though and I thing we have discussed it by personal > e-mails. > > - Olivia uses Hadamard/Welsh transformation, RS uses Reed Solomon > block code > - Olivia is decoded parallel on a constraned band, RS is decoded > parallel on the whole sound card spectrum. The channel separation is > half tone. > - RS code sends just one block with the mode ID. > > Olivia and RS decode both a lot of channels in parallel (at least the > original Olivia code from Pawel Jalocha does that) and it selects the > one, which gives highest correlation. This automatically gives the > answer for other party frequency. > > I received the RS code from Patrick, but I did not add it to > PocketDigi yet. I am busy now with firmware programming of ATS-3A, I > hope to teach it to modulate the single tone modes by programming its > DDS. It will be the ultimate portable digital set, hi. > > 73, Vojtech OK1IAK >
