Alan,
Of course, the FCC rules on SS are outdated and ROS should be allowed
due to its narrow spreading range, but the road to success is not to
just rename a spread spectrum modem to something else and try to fool
the FCC. This is a sure way to lose the battle. The genie is already out
of the bottle!
Instead, just petition the FCC for a waiver, or amendment, to the
regulations that are a problem, to allow FHSS as long as the spreading
does not exceed 3000 Hz and the signal is capable of being monitored by
third parties. Do this, and there is not a problem anymore. But, do not
try to disguise the fact that FHSS is being used by calling it something
else, as that undermines the credibilty of the author of the mode and
will make the FCC even more determined not to it on HF/VHF.
It looks to me that the tone frequencies are clearly being generated
independently from the data and then the data applied to the randomly
generated frequency. There is NO pattern to ROS like there is to FSK
modes, even to 32 tone FSK (Olivia 32-1000) or to 64 tone FSK
(MT63-2000). This is a signature of FHSS.
“/If/ it walks /like a duck/, quacks /like a duck/, /looks like a duck/,
it must be a /duck/”.
It looks like ROS really is FHSS when you look at it on a spectrum
analyzer, and the spectrum analyzer does not lie.
73 - Skip KH6TY
Alan Barrow wrote:
KH6TY wrote:
> The difference between ROS and MFSK16 at idle (i.e. no data input), is
> that MFSK16 has repetitive carriers in a pattern, but the ROS idle has
> no repetitive pattern and when data is input, the pattern still
> appears to be random. Note the additional carriers when I send six
> letter "N"'s in MFSK16. It then returns to the repetitive pattern of
> an MFSK16 idle. Note that the data (i.e. "N"'s created new carriers
> depending upon the data. In this case, the frequency carriers are data
> dependent.
>
> If ROS is just FSK144, then I expected to find a repeating pattern at
> idle, but I never see one, even after letting ROS idle for a long time
> in transmit.
It's pretty common in modems to randomize the data to prevent carriers
when sending all zero's or ones. Phone modems do it, I'm pretty sure P3
does, and other RF modems do.
I know of another amateur RF modem that had randomized spectra by
design. By this test it would have been considered spreadspectrum, but
it was not, it was mfsk with a randomizer. The randomizing algorithm was
provided to the FCC, and life was good. This was before SS was allowed
at all, and there was not a bit of discussion that it might have been
spread-spectrum.
If MFSK16 was randomized would it magically become spread-spectrum?
All I know is, this is not the spread spectrum everyone is worried is
going to ruin the bands! IE: traditional spread spectrum with bandwidth
expansion of 100-1000.
Have fun,
Alan
km4ba
