Fwd: Re: [digitalradio] A closer look at ROS]]
Tom Azlin N4ZPT
n4zpt at cox.net
Sun Feb 21 16:59:10 CST 2010
interested "debate" going on right now on the below reflector. Seems a
new sound card mode came out where the author declared it to be spread
spectrum. Thus a huge debate started along two paths. Was the mode SS in
the first place and if so was it legal. Splinter arguments than all the
other sound card mods are also thus not legal.
I have not looked to see if there is a separate psuedorandom spreading
code added to the carrier to pick up spreading gain. Of course there is
another mode that is used in ARRL traffic nets called Chip64 which is
also described by the author as SS. Which is being used.
Given AMRAD was part of the original SS approvals, what do you all think?
73, Tom n4zpt
-------- Original Message --------
Subject: Re: [digitalradio] A closer look at ROS]]
Date: Sun, 21 Feb 2010 17:30:50 -0500
From: KH6TY <kh6ty at comcast.net>
Reply-To: digitalradio at yahoogroups.com
To: digitalradio at yahoogroups.com
The FCC is only concerned with what happens to the resultant RF energy
and what is done with it, not how that RF is generated. In the case of
ROS, if the data is applied to an RF carrier and the frequency then
hopped, that would classify it as spread spectrum.
The rules are FCC rules and currently specifically specify spread
spectrum to be used only at 222Mhz and above. If it were not for that
specific reference and the statement by Jose that frequency hopping is
used, then the rules might be subject to interpretation. As it presently
is, Jose would have a tough time in a court of law to prove he does not
use frequency hopping or spread spectrum, as he has already claimed.
Our best chance to legally use ROS in the US is for the FCC to issue a
ruling. As amateurs, and not even lawyers, we are not competent to
second-guess the FCC's lawyers and as long as there are so many previous
claims that ROS is spread spectrum, we are stuck with that definition.
Our best hope is to get the FCC to amend the regulations, or make an
exception, to allow spread spectrum as long as it is capable of being
monitored by third parties and does not exceed the bandwidth of a phone
signal, and ROS would meet all of those conditions.
There are those who think that regulation by bandwidth would solve
everything, but there are also those who would love that chance to take
over the HF bands with automated messaging services so they do not have
to worry about crowding anymore. You can be thankful for regulations
that both protect, and also allow, with limitations, and that cannot be
changed without a sufficient period of public comment from all users so
that all sides can be heard from. The FCC adheres to such a process.
73 - Skip KH6TY
> There are two very common misconceptions in that theory. The first is
> that SS is unto itself not always a fully digital mode. and A, F, or J
> in that case indicates the nature of the narrow band signal being
> spread. So SS with a J designator would be an SSB signal digitally
> spread by the PN code. When received, it is de-spread to an analog SSB
> Sound card modes are not necessarily SSB. We use the SSB process as a
> convenient easy to deploy up converter when operating in these modes,
> the modulation occurs in the computer code and could be transmitted with
> varying degrees of ease by other means. CW via sound card is still CW as
> is the case with RTTY. ROS is no exception. It is quite possible to
> drive a DDS chip on frequency and accomplish the exact same result only
> at the expense of greater complexity.
> KH6TY wrote:
> > Rik,
> > Did you see the recent post by K3DCW?
> > The closest you get to a true definition in Part 97 is in section 97.3
> > Definitions, Para C, line 8:
> > /(8) SS/. Spread-spectrum emissions using bandwidth-expansion
> > modulation emissions having designators with A, C, D, F, G, H, J
> > or R as the first symbol; X as the second symbol; X as the third
> > symbol.
> > ROS uses SSB so the first designator is J (this meets the definition)
> > and it uses bandwidth-expansion. (this meets that definition as well)
> > Thus, taking this definition literally, it is indeed Spread Spectrum
> > and is thus illegal below 222MHz....at least that the conservative
> > interpretation that I'll stick with until we get a ruling otherwise.
> > ====================
> > Dave
> > K3DCW
> > Obviously, with such a new mode, there has been no ITU description of
> > ROS. If it used bandwidth expansion (i.e. frequency hopping), it is
> > obviously to be classified as spread spectrum. Whether or not modes
> > like MT63 and Olivia are essentially the same is debatable. The
> > problem seems to be the direct reference to bandwidth expansion (but
> > within the width of a phone signal), which, until ruled otherwise (and
> > I hope it will be) is spread spectrum according to the current FCC
> > rules, and is currently legal only above 222 Mhz.
> > 73 - Skip KH6TY
> > Rik van Riel wrote:
> >> On 02/21/2010 02:17 PM, w2xj wrote:
> >> > I have spent the last hour looking through part 97. I find nothing
> >> that
> >> > would prohibit ROS in the HF bands subject to adhering to those
> >> segments
> >> > where the bandwidth is allowed. In fact the rules would appear to
> >> > support such operation:
> >> Lets look at it in another way. Part 97.3 is quite specific
> >> about what modes are considered spread spectrum:
> >> (8) SS. Spread-spectrum emissions using bandwidth-expansion
> >> modulation emissions having designators with A, C, D, F,
> >> G, H, J or R as the first symbol; X as the second symbol;
> >> X as the third symbol.
> >> ROS has no ITU designator marking it as spread spectrum.
> >> Furthermore, from part 97.307 places this limitation on any
> >> data mode transmitted in the HF bands:
> >> (2) No non-phone emission shall exceed the bandwidth of a
> >> communications quality phone emission of the same
> >> modulation type. The total bandwidth of an independent
> >> sideband emission (having B as the first symbol), or a
> >> multiplexed image and phone emission, shall not exceed
> >> that of a communications quality A3E emission.
> >> ROS follows this rule.
> >> In short, ROS has not been ruled to be a spread spectrum mode
> >> by the FCC or the ITU, and fits within the bandwidth of a phone
> >> communications signal on HF.
> >> It also follows the common sense rule of not causing any harm
> >> on the HF bands. It really is not much different from the
> >> other data modulations out there. JT65, Throb and RTTY also
> >> have empty space between carrier positions.
> >> I would certainly try out ROS, if it weren't for the fact that
> >> I don't have a Windows PC and ROS does not seem to run anywhere
> >> else...
> >> --
> >> All rights reversed.
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