Thanks .... I think you make the same point as I am seeking ....
Just because the author of the program calls his great work spread spectrum does not necessarily make it so. Sorry Jose .... Here is partially why I ask for better clarification .... In Jose's documentation, one of his remarks seems to actually remove a qualifier of spread spectrum by his own statement as to why he did not do certain things. That is, in every spread spectrum system I have ever worked with (microwave, cordless phones, and numerous others), for the systems to work, each end had to be pre-programmed to a matching specific coded algorithm in order for the receivers and transmitters to hop frequencies in the exact same pattern and sync with each other. This pattern was pre-determined by that algorithm and NOT by ANY of the input data whatsoever. In other words, even if there were no input to the transmitter, it would still hop and transmit on it's pre-determined frequency pattern. The presence or absence of data at any given point in time would certainly affect the output of the transmitter at that particular instant, but would not affect the pre-determined frequency, but rather it's phase usually. NOW, with that said, this also would cause one other thing to happen, that has already been stated in the discussions. In true spread spectrum, if you were to look at the entire transmitted signal on an appropriate spectrum analyzer, you would see that the entire spectrum of the transmitted signal would be spread evenly throughout the bandwidth, regardless of input data. This is not necessarily true of an FSK / PSK signal in the short term. In the long term averaged over a period of time it may end up that way. Also of note, the "frequency hopping" characteristics of FSK/PSK modes are the result of the input data alone, not due to a pre-determined frequency pattern. Jose's documentation specifically mentioned NOT doing this for the reason of nobody would know what code to preset to be able to listen for CQ's, etc. Since Jose specifically chose not to implement this form of coding, to my way of thinking it also removes one of the specific defining points required to qualify as true spread spectrum. So the question remains .... is it really spread spectrum or not? Until that question is really answered, then any discussion of legality remains moot. Just because Jose declares it as spread spectrum does not make it that way. And unless a signal really is spread spectrum, then the well known laws against it's use on HF frequencies does not apply here. At the same time, if it does turn out that his definition IS correct and it IS spread spectrum rather than FSK or PSK (BPSK), then we now have numerous other common sound card based digital modes that become just as illegal because they operate the SSB transmitter in exactly the same way, by applying a variety of tones in different patterns to the audio input of it and them modulating it, which in turn causes the transmitter to output on a variety of different instantaneous frequencies based on that input data. The question of "If we run RTTY with 850 Hz shift like we did in the old days, has that turned into spread spectrum?" is a very valid question indeed ... John KE5HAM --- In digitalradio@yahoogroups.com, "jhaynesatalumni" <jhhay...@...> wrote: > > > > --- In digitalradio@yahoogroups.com, "John" <ke5ham3@> wrote: > > > > Thanks Skip, > > > > Unfortunately, this really does not get to the crux of my question(s). I > > understand how an SSB transmitter works, but that is not really what I am > > after. > > > > What I am driving at is if like this. If I use DM780 to run some version of > > digital mode via an SSB transceiver, it uses a tone or series of tone > > modulation/shifting to create the output of the transmitter, and not one > > single mode is called "spread spectrum" output, but is called FSK or PSK, > > etc. Now, we get into the aforementioned discussion regarding ROS, and > > suddenly, still via the microphone input of the same transmitter, those > > shifted frequencies are now called "spread spectrum" instead. I am having a > > great deal of difficulty understanding, other than the author happened to > > call his scheme "spread spectrum" in his technical documentation. > > > > That's a good question. If we run RTTY with 850 Hz shift like we > did in the old days, has that turned into spread spectrum? >
