The only entity competent to answer the question is the FCC, and the
accepted procedure when one is not sure is to ask for a clarification.
Unfortunately, it is everyone's legal responsibility to understand the
law and obey it. Since most of use cannot do that, we have to turn to
lawyers to do it. You may or may not like the answer given, but the FCC
does try to protect the ham bands for everyone and seems to make
interpretations on that basis. Digital users are a tiny minority of
users of the bands, but the FCC is accountable to all hams, so they must
try to do what is right for all hams, not just for a minority. If it
were not for that approach, the HF bands today might be covered with
automatic messaging systems and it would be hard to even find a place to
play or have a QSO without interference from an automatic station that
does not listen first, does not QRL, and does not share frequencies. We
may not like the time it takes for the process to play out, but that
gives everyone a chance to present their case before any rules are made
- EVERYONE, not just a vocal minority.
73 - Skip KH6TY
Alan Barrow wrote:
John 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.
>
OFDM used in Pactor 3 is legal due to it's low symbol rates and SSB
sized effective bandwidth. If prior to P3 someone asked if FDM was legal
on HF most would say no. Traditional FDM (frequency division
multiplexing) as practiced in the real world would not ever be legal on
HF. So technically it's FDM, but practically, it's not, as it's much
narrower bandwidth.
Lumping ROS in with Spread spectrum is similar. You can use FDM or SS
approaches on an audio modulated sideband signal and not meet practical
definitions. quack test- walks like a duck, must be a duck.
Regarding the perfect SSB transmitter sending a 1khz tone equaling CW at
a 1khz beat frequency, we all know there is a big difference between
theoretical and reality.
But in theory, ROS, P3, whatever could be represented by multiple
transmitter signals, so could technically fall into legal gray area. I'm
sure if we tried hard enough we could find a way to decide it's illegal,
and should be banned. And in reality, the FCC won't care, as it did not
meet the quack test of spread spectrum. :-)
I don't have a horse in this race, however. :-)
Have fun,
Alan
KM4BA
