--- In digitalradio@yahoogroups.com, "iv3nwv" <nico...@...> wrote: > > 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 agree with this, and in a letter I wrote to the RSGB RadCom (and copied to G4JNT the RadCom data modes columnist) I suggested that a portion of each band should be set aside for just such experimentation. One question, of course, is whether releasing the software for a new mode to all and sundry just so that they can fill their logs with local contacts using it counts as experimentation. It is not the ROS mode itself that is the problem, so much as the people who are using it. > > 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. > I agree. However I hope you would also agree that there is insufficient spectrum space to allow uncontrolled use of an infinite number of different modes. The argument that a frequency can be yours if no-one else is using it is all very well, but it cannot be practically implemented with modes that cannot communicate with one another to determine whether it is in use or not. To give a very real example of the moment, the Olivia mode uses specific frequencies or channels because it is a weak signal mode and it is possible to communicate with signals that can neither be heard nor seen on the waterfall. Olivia users tune their receivers to precise frequencies in order to listen for weak signals that they would not detect on the band at random. But ROS users are now being advised to use the same frequencies that Olivia has been using. This is inevitably leading to interference by ROS to Olivia (and quite possibly also by Olivia to ROS since that can also decode weak signals) which is resulting in exchanges that I have seen using some very bad language which does the hobby no credit at all. You will hopefully agree that there is not a limitless amount of space for all modes to have their own exclusive allocations. However I don't know how you can arrange for incompatible modes to share the same frequency without mutual interference. Therefore I would suggest that the only answer is to limit the number of modes that can be used and only allow new ones to go beyond the experimental stage into general use if they turn out to offer some significant benefit over existing ones. (Equally I would agree that you could deprecate the use of modes that have fallen out of favour to make way for newer ones.) Julian, G4ILO
