> If MFSK16 was randomized would it magically become spread-spectrum?
Alan, sorry I forgot to reply to this question.
The answer is yes, but only if the following three conditions are ALL
met (from the ROS documentation):
1. The signal occupies a bandwidth much in excess of the minimum
bandwidth necessary to send the information.
2. Spreading is accomplished by means of a spreading signal, often
called a code signal, which is independent of the data.
3. At the receiver, despreading (recovering the original data) is
accomplished by the correlation of the received spread signal with a
synchronized replica of the spreading signal used to spread the information.
Standard modulation schemes as frequency modulation and pulse code
modulation also spread the spectrum of an information signal, but they
do not qualify as spread-spectrum systems since they do not satisfy all
the conditions outlined above.
Looking at the comparison between ROS and MFSK16,
http://home.comcast.net/~hteller/SPECTRUM.JPG, it is easy to see that
MFSK16 is not FHSS, but ROS definitely is.
Another thing that a petition should include is a requirement that ROS
only be used BELOW the phone segments and ABOVE the narrowband data
segments. On 20m, that means only between 14.1 and 14.225, because ROS
is so wide.
BTW, this same issue came up during the "regulation by bandwidth" debate
when the ARRL HSMM (High Speed MultiMedia) proponents wanted to allow
wideband, short timespan, signals everywhere with the argument that they
last such a short time on any given frequency that they do not
interfere, but the fallacy to that argument is that when you get a
multitude of HSMM signals on at the same time, all together they can
ruin communication for narrow modes, like PSK31.
The other problem is that SHARING of frequencies requires that users of
one mode be able to communicate with users of another mode in the same
space so QRL or QSY can be used. It was realized that only CW used by
both parties would make this possible. ROS does not work well in a
crowded environment or with wideband QRM, so it must find a home
relatively clear of other mode QRM. This is just another job the FCC
must do in order to be sure a new mode does not create chaos. It has
already been shown that leaving that up just to hams does not work, and
the strongest try to take over the frequencies.
upper
73 - Skip KH6TY
Alan Barrow wrote:
If MFSK16 was randomized would it magically become spread-spectrum?
