It is still valid, Ted, and is described such in the Wikipedia
http://en.wikipedia.org/wiki/Frequency-hopping_spread_spectrum. I think
the FCC rules are definitely out of date, but identification is
essential to being about to share frequencies, so any code that prevents
that has no place on the ham bands. ROS is not like that, though, since
the synchronization is apparently contained in the reception code, so
anybody can copy. The FCC rules need to be amended, but that needs to be
done by petition. Until that is done, we are required to follow the
current rules whether we agree with them or not.
The other possible problem is "wide-spreading" spread spectrum. There
was a failed attempt about 5 years ago by the ARRL HSMM (High Speed
Multi-Media) proponents to allow spread spectrum on the HF bands with
the argument that the signal is spread so widely, each carrier appears
at any given frequency only a short time, so it would not significantly
interfere with other users of the frequency, and could, for example, be
allowed to cover the entire 20m band. However, that assumes only "one"
FHSS signal at a time. I think if you put on many at one time, in the
resulting aggregate, there could be continuous interference over the
entire width of the spectrum spread, since the spreading is
pseudorandom. You can see what happens when just more than one ROS user
tries to use the same frequency. They interfere with each other.
"A /million monkeys/ with typewriters will eventually write a
Shakespeare play".
73 - Skip KH6TY
theophilusofgenoa wrote:
I had the idea that a reason spread spectrum was not legal was that
the use of a psuedo-random spreading sequence lent itself to the
development of an unbreakable code (or at least a difficult to break
code) that would allow secret communications by people inimical to the
good old USA. And I think that is a valid point.
Ted Stone, WA2WQN
