I agree with Nino, theoretically it is correct to use as much bandwidth as possible, 3 kHz in the ROS case, but due to the small spreading, the ROS signal does not have a "negligble level" compared to others on the channel, so it is a halfbreed, it has spread spectrum characteristics, but does not quite behave like the "pure" definition.
ROS still had problems in version 1.6.3 and it is easy to notice that it works in a free channel, but does not stand burst errors (in fact, errors long as a packet or pactor frame length) and its ability to copy crumbles. That does not happen, at least so noticeably, with JT65 or Olivia. 73, Jose, CO2JA ---- El 05/03/2010 20:22, iv3nwv escribió: > Julian, > thanks for your comments. > > Yes, laws are laws. > Also the Hammurabi rule "If a man puts out the eye of an equal, his eye shall > be put out" was a law but I don't think that it would be of great help in our > modern society. > > I agree with you that simulations should be performed prior to any other "on > air" experiment. I think that this is already a common practice nowadays or > at least that nobody interested in a serious development would omit to > perform it today. > > I also agree that amateur bands are not just an experimenter's playground but > this implicitly means that they are not exclusive to "communicators". > If I were an experimenter I would like to see acknowledged my right to make > my experiments somewhere in our bands. I would have no interest interfering > other users activity, I would just need a portion of the spectrum where me or > other amateurs on the other side of the Atlantic Ocean were not considered > criminals just because we are validating a model on the field. > > I don't agree that we should use modes which have already been invented and > stop looking for new ones. Research and development in communications and in > information theory are everything but dead. > Turbo codes were submitted to the attention of the research community just > fiftheen years ago, when many had already missed the hope that the Shannon > channel capacity could be really approached. > Should Berrou, Glavieux and Thitimajshima have made more use of what had been > already invented instead of experimenting what had not be done yet? And what > about those who dedicated their time inventing new efficient algorithms to > decode LDPC (or Gallager's) codes, as David MacKay did few years later? > Koetter (unfortunately passed away at a still young age), one of the two > researchers who found an algebraic soft decision method to decode better than > before the Reed-Solomon codes, as those used in Joe's JT65, published his > work in 2003 or so. > Should we have stopped our alternatives to knowledge and technologies > available in 2002? I don't think so. > We should better keep up with news and new modes. > > Nico, IV3NWV
