There are two very common misconceptions in that theory. The first is that SS is unto itself not always a fully digital mode. and A, F, or J
in that case indicates the nature of the narrow band signal being spread. So SS with a J designator would be an SSB signal digitally spread by the PN code. When received, it is de-spread to an analog SSB signal. Sound card modes are not necessarily SSB. We use the SSB process as a convenient easy to deploy up converter when operating in these modes, the modulation occurs in the computer code and could be transmitted with varying degrees of ease by other means. CW via sound card is still CW as is the case with RTTY. ROS is no exception. It is quite possible to drive a DDS chip on frequency and accomplish the exact same result only at the expense of greater complexity. KH6TY wrote: > Rik, > > Did you see the recent post by K3DCW? > > The closest you get to a true definition in Part 97 is in section 97.3 > Definitions, Para C, line 8: > > /(8) SS/. Spread-spectrum emissions using bandwidth-expansion > modulation emissions having designators with A, C, D, F, G, H, J > or R as the first symbol; X as the second symbol; X as the third > symbol. > > ROS uses SSB so the first designator is J (this meets the definition) > and it uses bandwidth-expansion. (this meets that definition as well) > Thus, taking this definition literally, it is indeed Spread Spectrum > and is thus illegal below 222MHz....at least that the conservative > interpretation that I'll stick with until we get a ruling otherwise. > > > ==================== > Dave > K3DCW > > Obviously, with such a new mode, there has been no ITU description of > ROS. If it used bandwidth expansion (i.e. frequency hopping), it is > obviously to be classified as spread spectrum. Whether or not modes > like MT63 and Olivia are essentially the same is debatable. The > problem seems to be the direct reference to bandwidth expansion (but > within the width of a phone signal), which, until ruled otherwise (and > I hope it will be) is spread spectrum according to the current FCC > rules, and is currently legal only above 222 Mhz. > > 73 - Skip KH6TY > > > > > Rik van Riel wrote: >> >> >> On 02/21/2010 02:17 PM, w2xj wrote: >> > I have spent the last hour looking through part 97. I find nothing >> that >> > would prohibit ROS in the HF bands subject to adhering to those >> segments >> > where the bandwidth is allowed. In fact the rules would appear to >> > support such operation: >> >> Lets look at it in another way. Part 97.3 is quite specific >> about what modes are considered spread spectrum: >> >> (8) SS. Spread-spectrum emissions using bandwidth-expansion >> modulation emissions having designators with A, C, D, F, >> G, H, J or R as the first symbol; X as the second symbol; >> X as the third symbol. >> >> ROS has no ITU designator marking it as spread spectrum. >> >> Furthermore, from part 97.307 places this limitation on any >> data mode transmitted in the HF bands: >> >> (2) No non-phone emission shall exceed the bandwidth of a >> communications quality phone emission of the same >> modulation type. The total bandwidth of an independent >> sideband emission (having B as the first symbol), or a >> multiplexed image and phone emission, shall not exceed >> that of a communications quality A3E emission. >> >> ROS follows this rule. >> >> In short, ROS has not been ruled to be a spread spectrum mode >> by the FCC or the ITU, and fits within the bandwidth of a phone >> communications signal on HF. >> >> It also follows the common sense rule of not causing any harm >> on the HF bands. It really is not much different from the >> other data modulations out there. JT65, Throb and RTTY also >> have empty space between carrier positions. >> >> I would certainly try out ROS, if it weren't for the fact that >> I don't have a Windows PC and ROS does not seem to run anywhere >> else... >> >> -- >> All rights reversed. >> >> >
