Andy,
As I read it, the NPRM did not disturb the current FCC ruling that
spread spectrum is only allowed above 222 Mhz, so that is still in
force. What it did was modify the power and power monitoring requirements.
73 - Skip KH6TY
Andy obrien wrote:
I read the proposed rule making and did not find any reference to
frequency/band. So, where is it saying SS is allow but only on 220Mhz
and above ?
On Thu, Mar 18, 2010 at 6:11 PM, KH6TY <kh...@comcast.net
<mailto:kh...@comcast.net>> wrote:
Extensive tests on 70cm using ROS 16 baud spread spectrum have
been disappointing. ROS appears to be unable to survive the
Doppler shift and Doppler induced "flutter" so prevalent on that
band. The hope was that ROS 16 baud would make traditional
communications possible that were difficult on SSB phone because
of the Doppler shift and "flutter". However, the tests show that
Olivia 32-1000, in half the bandwidth, and Olivia 16-500, produce
print when ROS only prints garbage. This, together with the fact
that both stations must be within 400 Hz of each other before even
trying to communicate, instead of being able to tune with the
mouse as is possible with Olivia, makes it very difficult to
achieve a QSO on 70cm using ROS. Olivia has therefore proven to be
much more successful than ROS on UHF.
Tests using the ROS 1 baud variation will be made next, but the
slow speed of that mode is more suited to EME communications than
normal QSO's.
In two weeks of monitoring ROS 16 baud on 20m, there has been only
one observed case where the S/N was under where Olivia 32-1000 can
decode, so even on HF, there does not appear to be any
justification for using such a wide mode, even if spread spectrum
were permitted on HF in the US. Just use Olivia or MFSK16 instead
when band conditions are poor. The new narrow band ROS modes were
not tested, since a mode to do better than Olivia is what is
needed, and the spread spectrum mode of ROS held the best hope. As
it stands, only CW is better than Olivia under the worst
conditions, and only when copying by ear, but CW is only a little
better than Olivia 16-500. We have also found that the more narrow
Olivia modes (i.e. < 500 Hz wide) are also too greatly disturbed
by Doppler to be useful either.
If anyone is within 200 miles of FM02, has 100 watts and an
antenna gain of 17 dBi or greater, and would like to try ROS 16
baud on UHF, I am available to do that.
I promised to post the results of our attempts to use ROS on UHF
on this reflector, and this is what we have found. So, it looks
like Olivia is currently still the best digital mode to use on
UHF, VHF, or HF for normal (not EME) digital QSO's.
73 - Skip KH6TY
Trevor . wrote:
Regarding Spread Spectrum Notice of Proposed Rule Making (NPRM)
http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1
<http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1>
It proposes to reduce some of the restrictions on Spread Spectrum
but unfortunately does nothing about permitting the use at HF and
VHF of SS modes that completely fit within the bandwidth of a
phone signal (say 3 kHz on HF and 15 kHz on VHF).
It says comments can be filed on or before 30 days after date of
publication in the Federal Register. Instructions on how to file
comments on the NPRM only are listed on pages 6-7 in the NPRM.
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf
<http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf>
Electronic Comment Filing System
http://www.fcc.gov/cgb/ecfs/ <http://www.fcc.gov/cgb/ecfs/>
73 Trevor M5AKA
