Lester, I really appreciate your mannerly characterization of what I
wrote as "BS". :-(
From the Wikipedia, a more exact definition of spread spectrum is,
"*Frequency-hopping spread spectrum* (*FHSS*) is a method of
transmitting radio signals by rapidly switching a carrier
</wiki/Carrier_wave> among many frequency channels
</wiki/Channel_%28communications%29>, using a pseudorandom
</wiki/Pseudorandom> sequence known to both transmitter
</wiki/Transmitter> and receiver </wiki/Receiver_%28radio%29>. "
Please post here what your own spectral analysis finds, and state if you
are willing to testify to the FCC whether or not ROS is really FHSS.
Thanks.
73, Skip KH6TY
(No BS at this QTH!)
On 7/12/2010 11:58 AM, Lester Veenstra wrote:
This, as we say in the lightning fast chicken navy, the following is
simply "BS" : ' Anyone with DigiPan or any other PSK31 program with a
waterfall can verify that the frequency spreading is random and not a
function of the data, which is the signature of spread-spectrum.'
The use of a "randomizer" is not the mark of spread spectrum, but
rather the mark of a well-designed modem system, where a steady state
data in does not cause a lack of random transmit link data. The
receiver needs a steady stream of clock transitions in order to
maintain receive synchronization. The transmit waveform needs a
steady stream of pseudorandom data in order to maintain a minimum
carrier spectral density, than therefore reduce its potential to other
users. That is to say, making your transmit waveform appear noise
like (I did NOT say, under the noise), gives other modems the best
chance be minimally affected.
Randomness is not a differential to uniquely identify a spread
spectrum modulation. However, every spread spectrum system is
pseudorandom. A does not mean B, but B is A.
/Lester B Veenstra MØYCM K1YCM///
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*From:* [email protected]
[mailto:[email protected]] *On Behalf Of *KH6TY
*Sent:* Monday, July 12, 2010 12:21 PM
*To:* [email protected]
*Subject:* Re: [digitalradio] Moving ROS forward in the USA?
Andy,
I have been told by a FCC engineer, part of the evaluation group at
the FCC, whom I will not name, that ROS 16 baud and 1 baud has been
evaluated in the lab and "is" spread-spectrum and therefore illegal on
HF, not only because the author first said it was spread spectrum and
then changed his story.
Anyone with DigiPan or any other PSK31 program with a waterfall can
verify that the frequency spreading is random and not a function of
the data, which is the signature of spread-spectrum.
Just because someone "feels" it is not spread spectrum does not excuse
them from following the regulations and those who do not risk the
chance of FCC action against them once someone files a complaint.
There is no reason for the FCC to "reconsider" their decision, since
it is based on analysis as well as the author's declaration. What can
be done is to submit a petition to the FCC to allow limited bandwidth
spread spectrum on HF by showing it is not harmful to other users of
the bands. The instructions for submitting a petition are available on
the FCC website.
Radio amateurs are responsible for following the regulations, not just
interpreting them as they see fit.
ROS is legal above 222 Mhz, so freely use it there if you wish. It is
probably really good for EME.
73, Skip KH6TY
_._,___
