Re: [digitalradio] Re: Random data vs Spread Spectrum

[KH6TY]

Julian,

The "other side of the coin" is that we must share frequencies (because 
there is limited space), so in order to do that, it is necessary to be 
able to understand a request to QSY or a QRL. When there was only CW and 
phone, this was always possible, but with digital modes, if you do not 
decode a request in a different mode than you are using, you are unable 
to share. It helps to use RSID or operate in a place where others are 
using the same mode.


73, Skip KH6TY

On 7/14/2010 4:37 AM, g4ilo wrote:



--- In digitalradio@yahoogroups.com 
, "J. Moen"  wrote:

>
> I think if 3 kHz SSB is ok, that 2.25 kHz modes (ROS as an example) 
should be ok, as long as the frequencies chosen are prudent for the 
band and time of time.


I agree, if people had more flexibility as to where to operate it 
would be less of a problem. This is mainly the fault with band 
planning (designed, as someone else said, in the days when the only 
digital mode was RTTY) but also due to the fact that frequencies for 
ROS operation were specified rather than allowing people to work 
wherever they find a clear spot.


Although not the same issue as the legality of spread spectrum in the 
US it is the same kind of issue as I believe it is the case that you 
are not free to use digital modes outside the allocated digital sub 
bands whereas there is nothing to actually prevent anyone in the rest 
of the world from finding a quiet spot in the SSB sector to conduct 
their weak signal experiments using wide band modes as the band plans 
are only a "gentleman's agreement."


Julian, G4ILO

RE: [digitalradio] Re: Random data vs Spread Spectrum

[Lester Veenstra]

Alan:

 For what reason (technical advantage) would you advocate the  use of SS at 
HF. (My apologies, if I am off base,  for assuming that you would advocate the 
use of SS, by the “lost cause” descriptor) .

   Les

 

 

 

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From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On 
Behalf Of Alan Barrow
Sent: Wednesday, July 14, 2010 1:16 AM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum

 

  

……..

All that said, I'm not expecting to see any SS on HF by hams in the next
decade or two. I view it as a lost cause ………l


Alan
km4ba

Re: [digitalradio] Re: Random data vs Spread Spectrum

[KH6TY]

Alan,

Thanks for taking the time for a comprehensive reply! Remembering what 
happens during a contest with overcrowding made me wonder. The problem 
is that, with stations operating all independently, it is difficult to 
determine when throughput drops to the point it is not worth the effort. 
If you have dedicated channels to work with, that is quite different 
from the random frequencies hams choose when chasing DX or contesting at 
which time usage is a maximum. I was not surprised when ROS could not 
handle more than one QSO on the channel and the author tried to extend 
that to only two, because the spreading was just too small. Without 
scanning receivers like SDR's, he is constrained to the typical IF 
bandpass of transceivers already in the field, so it is just not 
possible to achieve the benefits of FHSS under those conditions.


We run a digital FM net (using DominoEX) where most stations are both 
under limiting and under 20 dB quieting, and even  with FM, it is 
important not to have the general noise level increased, just like it is 
for weak signal SSB or CW communications. I think it all goes back to 
not having control of the channel and the number of stations trying to 
use it simultaneously, which is much different than wired communications 
or commercial channels where sharing and access can be controlled.


Yes, I also think that it is best we leave DSSS for now and concentrate 
on modes that do the job well until something really better surfaces.


Thanks for satisfying my curiosity!

73, Skip KH6TY

On 7/13/2010 10:48 PM, Alan Barrow wrote:


KH6TY wrote:
>
>
> Alan,
>
> What happens, for example, if 100 DSSS stations are all on at the same
> time, on the same beginning and ending frequencies, because everyone
> assumes his presence at any one frequency is too short to be noticed?
>
> Will they interfere with each other, or will they collectively
> interfere with other users of the frequency, such as SSB stations?

All valid questions. You know the answer to most of them.

DSSS without CDMA, hold off, etc would neither work or be desired beyond
a certain "loading" (number of users).
> When you say "multiple" how many would that be with a spreading factor
> of 100?

Like you, I'd have to dig out the math, make some assumptions. There is
an answer, and it's greater than 1, and less than 100 for sure. :-)

Based on very rough math, and fuzzy assumptions, my initial calcs were
that it would take over 10 simultaneous DSSS to be detectable at psk
data rates with a spreading factor of 100.

More than that to be interference to a typical SSB signal. Remember,
just because a chip wanders into an SSB bandwidth slot does not mean it
will interfere with an SSB signal due to SSB filtering, response curves,
etc. That bit in the bottom 50 hz of an SSB slot will not be detected.
Likewise those in the "guard bands" between typical SSB signal spacing.

Likewise, since the energy is widely distributed there are no
significant sidebands that are much easier to detect/hear and become
interference.

But that was just a concept thrown out to make people realize that all
DSSS is not like ROS. Nor like the high data rate strong signal DSSS
seen on higher bands.

We need to separate the concept from the flawed implementation, that's
my point. I do believe in the future we will want to revisit DSSS with
CDMA as an alternative to the chaos of RTTY/WINMOR/P3/ALE/SSTV/whatever
we have now. Not to the exclusion of legacy weak signal modes. But as a
more efficient way to maximize throughput (users * data of any type) of
the very limited HF resource we have.

We'd have to do the math, but I'm pretty confident that for any chunk of
bandwidth (say, 20khz or greater) you could support more simultaneous
users at a given data rate with DSSS or similar wideband mode with CDMA
than the same chunk with SSB afsk modems. It's simply more efficient,
does not have the guard band issues, etc.

It will never happen in our lifetimes due to the hold that legacy modes
have. With some justification. But that does not mean we should paint
ourselves into a corner where it could never be discussed, much less
proposed.
>
> It seems to me that enough chips randomly spread over the band (by
> enough multiple stations) could also raise the general noise level,
> even if they were very weak. This was a concern of weak signal 
operators.


This is true and valid for weak signal areas. It's not for strong signal
modes. Even including SSB, and you could do much in between FM channels
with minimal impact to FM qso's. There's nothing that states DSSS has to
be evenly spread across it's range, though it helps with processor gain.
You could have a sequence that only hit the guard bands between 10m FM
channels for example.

> For example, suppose it was decided to let multiple DSSS stations span
> the whole length of the 20m phone band so there was sufficient
> spreading. How many on the air at one time would it take to create
> noticeable QRM to

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Alan Barrow]

KH6TY wrote:
>
>
> Alan,
>
> What happens, for example, if 100 DSSS stations are all on at the same
> time, on the same beginning and ending frequencies, because everyone
> assumes his presence at any one frequency is too short to be noticed?
>
> Will they interfere with each other, or will they collectively
> interfere with other users of the frequency, such as SSB stations?

All valid questions. You know the answer to most of them.

DSSS without CDMA, hold off, etc would neither work or be desired beyond
a certain "loading" (number of users).
> When you say "multiple" how many would that be with a spreading factor
> of 100?

Like you, I'd have to dig out the math, make some assumptions. There is
an answer, and it's greater than 1, and less than 100 for sure. :-)

Based on very rough math, and fuzzy assumptions, my initial calcs were
that it would take over 10 simultaneous DSSS to be detectable at psk
data rates with a spreading factor of 100.

More than that to be interference to a typical SSB signal. Remember,
just because a chip wanders into an SSB bandwidth slot does not mean it
will interfere with an SSB signal due to SSB filtering, response curves,
etc.   That bit in the bottom 50 hz of an SSB slot will not be detected.
Likewise those in the "guard bands" between typical SSB signal spacing.

Likewise, since the energy is widely distributed there are no
significant sidebands that are much easier to detect/hear and become
interference.

But that was just a concept thrown out to make people realize that all
DSSS is not like ROS. Nor like the high data rate strong signal DSSS
seen on higher bands.

We need to separate the concept from the flawed implementation, that's
my point. I do believe in the future we will want to revisit DSSS with
CDMA as an alternative to the chaos of RTTY/WINMOR/P3/ALE/SSTV/whatever
we have now. Not to the exclusion of legacy weak signal modes. But as a
more efficient way to maximize throughput (users * data of any type) of
the very limited HF resource we have.

We'd have to do the math, but I'm pretty confident that for any chunk of
bandwidth (say, 20khz or greater) you could support more simultaneous
users at a given data rate with DSSS or similar wideband mode with CDMA
than the same chunk with SSB afsk modems. It's simply more efficient,
does not have the guard band issues, etc.

It will never happen in our lifetimes due to the hold that legacy modes
have. With some justification. But that does not mean we should paint
ourselves into a corner where it could never be discussed, much less
proposed.
>
> It seems to me that enough chips randomly spread over the band (by
> enough multiple stations) could also raise the general noise level,
> even if they were very weak. This was a concern of weak signal operators.

This is true and valid for weak signal areas. It's not for strong signal
modes. Even including SSB, and you could do much in between FM channels
with minimal impact to FM qso's. There's nothing that states DSSS has to
be evenly spread across it's range, though it helps with processor gain.
You could have a sequence that only hit the guard bands between 10m FM
channels for example.

> For example, suppose it was decided to let multiple DSSS stations span
> the whole length of the 20m phone band so there was sufficient
> spreading. How many on the air at one time would it take to create
> noticeable QRM to SSB phone stations, or raise the noise background if
> they were on VHF?

There would have to be CDMA of some form. But the answer is still more
than one, less than many. You are still only using the net bandwidth
even when spread. IE: You are not truly using 50khz just because the
signal is spread across that range. Because you are not using it
exclusively. It's only when many, many users were active simultaneously
that it would reach interference levels. Likewise, the SSB signals would
surface as bit errors to the DSSS, so throughput would go down when it
was crowded with SSB signals.
> I ask this because I believe that the question arose several years ago
> regarding allowing hi-speed multimedia to operate over 20 kHz on 20m,
> which may be OK for one station, but what happens if there are 100
> stations doing the same thing?

High speed wide band is different than widely spread DSSS. It would
absolutely interfere with anything in that bandwidth, sounding like
white noise.

But similar questions pop up. Given 20 khz would typically handle 5-6
SSB signals with guardbands, could you beat the throughput with that one
20khz signal? Add CDMA, and would that channel carry more traffic than
the 5-6 SSB signals with P3? (Currently the ham legal throughput leader)

There are tradeoffs with multi-path, fading, etc. long/short symbol
lengths. None are perfect. But our current approach is not either. :-)

I'm not in favor of plopping hi-fi audio or multimedia wide band signals
in 20m SSB space. But do I think there should be options to experiment
(tightly controlled) with a CD

Re: [digitalradio] Re: Random data vs Spread Spectrum

[KH6TY]

Alan,

What happens, for example, if 100 DSSS stations are all on at the same 
time, on the same beginning and ending frequencies, because everyone 
assumes his presence at any one frequency is too short to be noticed?


Will they interfere with each other, or will they collectively interfere 
with other users of the frequency, such as SSB stations?


When you say "multiple" how many would that be with a spreading factor 
of 100?


It seems to me that enough chips randomly spread over the band (by 
enough multiple stations) could also raise the general noise level, even 
if they were very weak. This was a concern of weak signal operators.


For example, suppose it was decided to let multiple DSSS stations span 
the whole length of the 20m phone band so there was sufficient 
spreading. How many on the air at one time would it take to create 
noticeable QRM to SSB phone stations, or raise the noise background if 
they were on VHF?


I ask this because I believe that the question arose several years ago 
regarding allowing hi-speed multimedia to operate over 20 kHz on 20m, 
which may be OK for one station, but what happens if there are 100 
stations doing the same thing?


If there are enough randomly dispersed chips, won't they eventually fill 
the entire area with if there are enough of them?


I studied communications theory and auto-correlation functions, etc., 50 
years ago in college, but unfortunately I don't remember much of it at all!


73, Skip KH6TY

On 7/13/2010 8:15 PM, Alan Barrow wrote:


W2XJ wrote:
>
>
> It is generally accepted that 10 times bandwidth is the minimum
> necessary to achieve enough processing gain to make the use of SS
> worthwhile.

Not only is it not worth doing, it also increased chances of
interference. I'm not aware of any weak signal DSSS using spreading
factors of less than 100. The lowest I've seen is 16 for consumer strong
signal wide band stuff. And that's just due to economics, not for
performance.

Take that same psk'ish data rate, use a more conventional spreading
factor of 128, and you could see decent weak signal performance due to
processor gain, and most likely not impact strong signal legacy modes in
the same band segment.

Of course, you could not do this with an audio SSB approach. But you
could certainly decode it with SDR, which is why we should not throw out
the baby with the bathwater.

Remember, ROS somewhat sucked because it's spreading was so small there
was a large likelihood of any given bit interfering with another weak
signal.

Spread that out, and it's only the individual "chips" (fraction of a
data bit) that is on any given frequency at any given time.

Put another way, you could probably run multiple DSSS signals at psk
data rates in the SSB (voice) sub-bands with minimal impact to existing
qso's if spread like conventional DSSS. You could see the impact on a
properly setup monitor, but realistically the SSB stations would not
detect the chips in their slot.

Not that I'm proposing we do so, just that we need to fully understand
the technology, it's potential advantages & impacts before we throw it 
out.


All that said, I'm not expecting to see any SS on HF by hams in the next
decade or two. I view it as a lost cause and we'll just learn to deal
with the beeps & bloops from advance digital modes from non-amateur
services on our shared bands.

Have fun,

Alan
km4ba

RE: [digitalradio] Re: Random data vs Spread Spectrum

[Dave AA6YQ]

The definition of Spread Spectrum in 97.3(c)8 rests on the phrase "using
bandwidth-expansion modulation emissions". This clearly lacks the technical
precision required

- for digital mode developers to know what techniques can and can not be
incorporated in modes used by US stations (e.g. pseudo-random coding, as
Alan points out below)

- for US digital mode users to determine if and on what frequencies an
accurately-documented mode can be used

A constructive response to the Ros debacle would be to propose improved
language for 97.3(c)8 that is clear and unambiguous. Assuming the proposed
definition does not increase the likelihood of causing harmful interference
or permit encrypted communications (concerns implicit in 97.311), the FCC
would likely welcome a change that improves our ability to abide by the
regulations without consuming their scarce resources.

73,

Dave, AA6YQ



-Original Message-
From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com]on
Behalf Of Alan Barrow
Sent: Tuesday, July 13, 2010 1:22 PM
To: digitalradio@yahoogroups.com
Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum



graham787 wrote:
> So, if bits are added to the transmit waveform that are not performing a
function of helping to re-create an error free replication of the input
data, it meets my test as spread spectrum. If the symbols in the transmit
waveform cannot be predicted by the previous sequence of bits over time at
the input, it also would meet my test as spread spectrum. To reiterate on
this point, just because the symbols of the transmit waveform are changing
during an unchanging input, does not imply spread spectrum.
>
> Instead, they may well be the result of a defined randomizer process
followed by multiple layers of FEC and modulation coding.
>

While I do not support ROS in any form, I think the group is on a very
slippery slope here with well intentioned but misinformed definitions &
tests that may haunt us in the future!

Just the fact that data is randomized does not define SS. There has to
be a spreading factor, which has some rough definitions based on
practical applications, but is not addressed in any FCC definitions.

Skip's well intentioned but overly simplistic test of looking at the bit
stream is not enough to define SS. There are many legitimate reasons to
code data resulting in a pseudo-random fashion that have nothing to do
with SS!

The most common is coding so the transitions between bit's can easily be
detected even in noise. It's a problem when sequential bits look the same.

You can also factor in FEC. There are many, many writeups on
convolutional encoding that go into this. (Viterbi & reed-solomon are in
wide usage)

But it's also useful to spread the energy out in the bandwidth and avoid
sidebands created by single tones of long duration. There are multiple
modem/modes which do this, some in very wide usage.

So yes, SS (really DSSS) is pseudo-random. But not all pseudo-random
coding is SS, and we should not be proposing that as a litmus test!

The real test should be:
- direct or BPSK modulation via a pseudo-random code in addition to any
coding for FEC (convolutional, etc)
- A spreading factor significantly higher than the original data rate

The 2nd item is the key part, and it's listed but virtually never quoted
in this group, but is listed in nearly all the SS definitions. Nor is it
addressed in the FCC part 97 rules.

It's not enough that the bandwidth is higher than the data rate would
imply, as nearly all modes with FEC would fail that by definition.

The key is the "significantly wider" aspect, also referred to in
ITU/IEEE definitions as "typically orders of magnitude greater than the
data rate". And this is why many engineers question whether any SSB
generated mode could be "real" SS. ROS only did it by having the
original data rate lower than the SSB bandwidth.

About the lowest commercial DSSS implementations use a spreading factor
of 16:1, and that's for consumer grade without noise performance concerns.

Most DSSS implementations in the real world use spreading factors of 100
or greater, as that's when you start seeing significant noise recovery
improvements.

In DSSS, the "processor gain" which improves noise resilience is
directly related to the spreading factor.

I've posted multiple definitions from the ITU & IEEE in the past for
DSSS. Wikipedia, which has some good information, does not constitute a
formal definition like the ITU & IEEE references do. (Part of the reason
that wikipedia is not admissible as sources for college & research papers).

There is no shortage of formal definitions, we should not have to invent
our own. There are also some very readable definitions from mfg's for
their DSSS components. Like this one:
< http://www.maxim-ic.com/app-notes/index.mvp/id/1890 >

So

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Alan Barrow]

W2XJ wrote:
>
>
> It is generally accepted that 10 times bandwidth is the minimum
> necessary to achieve enough processing gain to make the use of SS
> worthwhile.

Not only is it not worth doing, it also increased chances of
interference. I'm not aware of any weak signal DSSS using spreading
factors of less than 100. The lowest I've seen is 16 for consumer strong
signal wide band stuff. And that's just due to economics, not for
performance.

Take that same psk'ish data rate, use a more conventional spreading
factor of 128, and you could see decent weak signal performance due to
processor gain, and most likely not impact strong signal legacy modes in
the same band segment.

Of course, you could not do this with an audio SSB approach. But you
could certainly decode it with SDR, which is why we should not throw out
the baby with the bathwater.

Remember, ROS somewhat sucked because it's spreading was so small there
was a large likelihood of any given bit interfering with another weak
signal.

Spread that out, and it's only the individual "chips" (fraction of a
data bit) that is on any given frequency at any given time.

Put another way, you could probably run multiple DSSS signals at psk
data rates in the SSB (voice) sub-bands with minimal impact to existing
qso's if spread like conventional DSSS. You could see the impact on a
properly setup monitor, but realistically the SSB stations would not
detect the chips in their slot.

Not that I'm proposing we do so, just that we need to fully understand
the technology, it's potential advantages & impacts before we throw it out.

All that said, I'm not expecting to see any SS on HF by hams in the next
decade or two. I view it as a lost cause and we'll just learn to deal
with the beeps & bloops from advance digital modes from non-amateur
services on our shared bands.

Have fun,

Alan
km4ba

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Alan Barrow]

g4ilo wrote:
> I don't know if that is a dig at one of the arguments I have made in the past,

Certainly not directed at you as an individual. I just feel that things
like sustained throughput which includes the effect of FEC & processor
gain in the case of SS need to be included.

So it's not as simple as 2.2khz bandwidth divided by 128 bps as a figure
of merit.

Skip's testing did show that for it's 2.2khz bandwidth, ROS was not the
leader in throughput.

What will never be known is if multiple ROS signals could have shared
that bandwidth without interference, or if it could have lived in large
signal (SSB, FM, etc) areas without interference.

>  but I do believe that 2.25kHz ROS was too wide for our existing HF bands. 
> Regardless of the merits or otherwise of a mode, people can't go on inventing 
> new modes unless they can also come up with a place for them to be used that 
> doesn't squeeze out existing users. 
Here we disagree somewhat. I would mostly agree for areas like 40m,
especially if multiple channels were used like ROS did. But I don't
agree that a new & otherwise legal mode that is SSB width should be
excluded just because the bands can be crowded.

If we followed your recommendations, SSB, SSTV, PSK, all the digital
modes, etc would never have been allowed to be used.

This is not to be construed that the approach the ROS implementor took
was a model of how things should proceed!

> the chances of finding 2.25kHz of 20m unoccupied are pretty slim at any time.
>   

If the mode is otherwise legal, it's up to the operator to find a hole
to operate. That's not a matter for legislation. :-)

Personally, I think we missed a chance to see what could be done with an
AFSK based SS approach in the wider & less used bands. Test in the
strong signal areas, where interference to legacy modes would be minimal.

Maybe DSSS between the FM frequencies on 10m where there would not be
interference to each other. Use a wider spreading sequence to increase
processor gain (and improve noise performance). Add in a CDMA approach
to allow multiple users in the same slots.

There are many possibilities which could be explored.

If your point is that 3 SSB width slots in the crowded 40m data section
was not appropriate, I agree! Other bands? Not so sure. :-)

Have fun,

Alan
km4ba

Re: [digitalradio] Re: Random data vs Spread Spectrum

[rein0zn]

Very well stated, separate questions.

73 Rein W6SZ

-Original Message-
>From: "J. Moen" 
>Sent: Jul 13, 2010 6:37 PM
>To: digitalradio@yahoogroups.com
>Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum
>
>This question of bandwidth for various modes and where to squeeze in the wider 
>modes is a good topic.  Reminds me of the folks who really like enhanced 
>fidelity SSB (3.5 out to nearly 5 kHz), or AM.  There are many bands at 
>certain times of day that have lots of space for those modes, but I'd hope 
>those hams would be kind to the rest of us, for example during a contest or 
>when certain bands are chock-full.  I think if 3 kHz SSB is ok, that 2.25 kHz 
>modes (ROS as an example) should be ok, as long as the frequencies chosen are 
>prudent for the band and time of time.  That discussion is entirely separate 
>from the US legal questions about SS modes on HF.
>
>  Jim - K6JM
>
>  - Original Message - 
>  From: g4ilo 
>  To: digitalradio@yahoogroups.com 
>  Sent: Tuesday, July 13, 2010 2:35 PM
>  Subject: [digitalradio] Re: Random data vs Spread Spectrum
>
>  --- In digitalradio@yahoogroups.com, Alan Barrow  wrote:
>  >
>  > - Simplistic bandwidth comparisons that do not factor in total
>  > throughput. (IE: The effect of processor gain, FEC, etc). I don't think
>  > ROS was stellar here, but the idea that a wider mode for X data rate is
>  > worse than a narrower mode is flawed. Otherwise we'd all be using RTTY.
>  > FEC increases bandwidth for the same data rate, but the trade off
>  > surfaces over sustained measurement in real (difficult) HF conditions.
>  > Skip's work did show there was not a big win for ROS, so we arrived at
>  > the right spot. But many were banning just because it was wider than
>  > their favorite mode!
>
>  I don't know if that is a dig at one of the arguments I have made in the 
> past, but I do believe that 2.25kHz ROS was too wide for our existing HF 
> bands. Regardless of the merits or otherwise of a mode, people can't go on 
> inventing new modes unless they can also come up with a place for them to be 
> used that doesn't squeeze out existing users. Even three channels was 
> patently inadequate for the number of users wishing to use ROS with the 
> result that most of the contacts made, as evidenced by the spots posted here, 
> were anything but weak signal DX as the chances of finding 2.25kHz of 20m 
> unoccupied are pretty slim at any time.
>
>  Julian, G4ILO

Re: [digitalradio] Re: Random data vs Spread Spectrum

[J. Moen]

This question of bandwidth for various modes and where to squeeze in the wider 
modes is a good topic.  Reminds me of the folks who really like enhanced 
fidelity SSB (3.5 out to nearly 5 kHz), or AM.  There are many bands at certain 
times of day that have lots of space for those modes, but I'd hope those hams 
would be kind to the rest of us, for example during a contest or when certain 
bands are chock-full.  I think if 3 kHz SSB is ok, that 2.25 kHz modes (ROS as 
an example) should be ok, as long as the frequencies chosen are prudent for the 
band and time of time.  That discussion is entirely separate from the US legal 
questions about SS modes on HF.

  Jim - K6JM

  - Original Message - 
  From: g4ilo 
  To: digitalradio@yahoogroups.com 
  Sent: Tuesday, July 13, 2010 2:35 PM
  Subject: [digitalradio] Re: Random data vs Spread Spectrum

  --- In digitalradio@yahoogroups.com, Alan Barrow  wrote:
  >
  > - Simplistic bandwidth comparisons that do not factor in total
  > throughput. (IE: The effect of processor gain, FEC, etc). I don't think
  > ROS was stellar here, but the idea that a wider mode for X data rate is
  > worse than a narrower mode is flawed. Otherwise we'd all be using RTTY.
  > FEC increases bandwidth for the same data rate, but the trade off
  > surfaces over sustained measurement in real (difficult) HF conditions.
  > Skip's work did show there was not a big win for ROS, so we arrived at
  > the right spot. But many were banning just because it was wider than
  > their favorite mode!

  I don't know if that is a dig at one of the arguments I have made in the 
past, but I do believe that 2.25kHz ROS was too wide for our existing HF bands. 
Regardless of the merits or otherwise of a mode, people can't go on inventing 
new modes unless they can also come up with a place for them to be used that 
doesn't squeeze out existing users. Even three channels was patently inadequate 
for the number of users wishing to use ROS with the result that most of the 
contacts made, as evidenced by the spots posted here, were anything but weak 
signal DX as the chances of finding 2.25kHz of 20m unoccupied are pretty slim 
at any time.

  Julian, G4ILO

Re: [digitalradio] Re: Random data vs Spread Spectrum

[rein0zn]

Julian

I apologize up front, but I do not believe you monitor the bands
even the CW sections with a sdr ( wide waterfall ) display.

If do did this, your monitor is defective, I am sorry!

   Watching 40 meter or 30 m or 20 m from a spot in the Eastern
part of the Netherlands:

http://websdr.ewi.utwente.nl:8901/

it can't look much different on the other side of the North Sea.

Frequency allocations is a matter of the IARU of whoever. Perhaps 
these days the European Government over there.

So this argument/anti ROS reason does no carry the day. Is it
up to Mr Ros to assign ROS frequencies as a little Dictator?
NO

But it has Nothing to do with ROS being legal in the US or where ever.

73 Rein W6SZ



   



-Original Message-
>From: g4ilo 
>Sent: Jul 13, 2010 9:35 PM
>To: digitalradio@yahoogroups.com
>Subject: [digitalradio] Re: Random data vs Spread Spectrum
>
>
>
>--- In digitalradio@yahoogroups.com, Alan Barrow  wrote:
>>
>> - Simplistic bandwidth comparisons that do not factor in total
>> throughput. (IE: The effect of processor gain, FEC, etc). I don't think
>> ROS was stellar here, but the idea that a wider mode for X data rate is
>> worse than a narrower mode is flawed. Otherwise we'd all be using RTTY.
>> FEC increases bandwidth for the same data rate, but the trade off
>> surfaces over sustained measurement in real (difficult) HF conditions.
>> Skip's work did show there was not a big win for ROS, so we arrived at
>> the right spot. But many were banning just because it was wider than
>> their favorite mode!
>
>I don't know if that is a dig at one of the arguments I have made in the past, 
>but I do believe that 2.25kHz ROS was too wide for our existing HF bands. 
>Regardless of the merits or otherwise of a mode, people can't go on inventing 
>new modes unless they can also come up with a place for them to be used that 
>doesn't squeeze out existing users. Even three channels was patently 
>inadequate for the number of users wishing to use ROS with the result that 
>most of the contacts made, as evidenced by the spots posted here, were 
>anything but weak signal DX as the chances of finding 2.25kHz of 20m 
>unoccupied are pretty slim at any time.
>
>Julian, G4ILO
>
>
>
>
>
>http://www.obriensweb.com/digispotter.html
>Chat, Skeds, and "Spots" all in one (resize to suit)
>
>Facebook= http://www.facebook.com/pages/digitalradio/123270301037522
>
>Yahoo! Groups Links
>
>
>

Re: [digitalradio] Re: Random data vs Spread Spectrum

[rein0zn]

So 10 times is not a property of SS. Yes

73 Rein W6SZ

-Original Message-
>From: W2XJ 
>Sent: Jul 13, 2010 8:46 PM
>To: digitalradio@yahoogroups.com
>Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum
>
>It is generally accepted that 10 times bandwidth is the minimum necessary to
>achieve enough processing gain to make the use of SS worthwhile.
>
>
>On 7/13/10 3:55 PM, "J. Moen"  wrote:
>
>>  
>>  
>>  
>>
>> 
>>  
>> There's the generally accepted definition of SS, quoted below and referring 
>> to
>> bandwidths greatly exceeding what's necessary, and then there's the way the
>> FCC regs are written, which do not refer to that definition.
>>  
>> I think just about everyone, or maybe absolutely everyone who cares about the
>> FCC regs, thinks in this case they are inappropriate, but the fact is, they 
>> do
>> not allow for narrow-band SS, even though it would cause no real harm.
>>  
>> The regs should be changed, but until they are, we in the US can not use SS
>> below 220, or we can move to another country, or we can violate the regs,
>> and/or we can campaign to change them.  But saying you don't agree with a law
>> so you don't have to follow it is not the right way.
>>  
>>   Jim - K6JM
>>  
>>>  
>>> - Original Message -
>>>  
>>> From:  rein...@ix.netcom.com
>>>  
>>> To: digitalradio@yahoogroups.com
>>>  
>>> Sent: Tuesday, July 13, 2010 11:23  AM
>>>  
>>> Subject: Re: [digitalradio] Re: Random  data vs Spread Spectrum
>>>  
>>> 
>>> Hi Alan, 
>>> 
>>> Why did you wait so long with contributing here?
>>> Please  explain.
>>> 
>>> ++ In Feb of this year I quoted from the ARRL's Spread  Spectrum Source book
>>> page 5-2 ++
>>> 
>>> " Spread Spectrum Fundamentals  "
>>> 
>>> SS systems employ radio frequency bandwidths that greatly exceed the
>>> bandwidth necessary
>>> to convey the intelligence.
>>> 
>>> Bandwidths for SS  systems generally run from 10 to 100 times the 
>>> information
>>> rate.
>>> 
>>> etc  etc.
>>> 
>>> I got shouted out of the Group by addressing the use of ROS in the  US by 
>>> the
>>> experts on
>>> SS.
>>> 
>>> 73 Rein W6SZ
>>  
>>
>> 
>> 
>

Re: [digitalradio] Re: Random data vs Spread Spectrum

[W2XJ]

It is generally accepted that 10 times bandwidth is the minimum necessary to
achieve enough processing gain to make the use of SS worthwhile.


On 7/13/10 3:55 PM, "J. Moen"  wrote:

>  
>  
>  
>
> 
>  
> There's the generally accepted definition of SS, quoted below and referring to
> bandwidths greatly exceeding what's necessary, and then there's the way the
> FCC regs are written, which do not refer to that definition.
>  
> I think just about everyone, or maybe absolutely everyone who cares about the
> FCC regs, thinks in this case they are inappropriate, but the fact is, they do
> not allow for narrow-band SS, even though it would cause no real harm.
>  
> The regs should be changed, but until they are, we in the US can not use SS
> below 220, or we can move to another country, or we can violate the regs,
> and/or we can campaign to change them.  But saying you don't agree with a law
> so you don't have to follow it is not the right way.
>  
>   Jim - K6JM
>  
>>  
>> - Original Message -
>>  
>> From:  rein...@ix.netcom.com
>>  
>> To: digitalradio@yahoogroups.com
>>  
>> Sent: Tuesday, July 13, 2010 11:23  AM
>>  
>> Subject: Re: [digitalradio] Re: Random  data vs Spread Spectrum
>>  
>> 
>> Hi Alan, 
>> 
>> Why did you wait so long with contributing here?
>> Please  explain.
>> 
>> ++ In Feb of this year I quoted from the ARRL's Spread  Spectrum Source book
>> page 5-2 ++
>> 
>> " Spread Spectrum Fundamentals  "
>> 
>> SS systems employ radio frequency bandwidths that greatly exceed the
>> bandwidth necessary
>> to convey the intelligence.
>> 
>> Bandwidths for SS  systems generally run from 10 to 100 times the information
>> rate.
>> 
>> etc  etc.
>> 
>> I got shouted out of the Group by addressing the use of ROS in the  US by the
>> experts on
>> SS.
>> 
>> 73 Rein W6SZ
>  
>
> 
> 

Re: [digitalradio] Re: Random data vs Spread Spectrum

[W2XJ]

Very simple change just add ³greater than 3 khz² to the existing rules.


On 7/13/10 3:28 PM, "Dave Wright"  wrote:

>  
>  
>  
>
> 
> I think that a lot of people are missing the point with ROS and Spread
> Spectrum here in the US.
> 
> The author defined it as Spread Spectrum, only changing it to FSK144 (or
> whatever) after being told that SS was not allowed below 1.25m in the US.  The
> FCC rules don't mention bandwidth in relationship to SS, they don't say that
> it "must employ bandwidths that greatly exceed the bandwidth necessary to
> convey the intelligence", nor do they reference any Wikipedia/ARRL/RSGB/ITU or
> other organization's definition.  They simply mention SS as not being allowed
> below 1.25m.  So, you can say that it is only 2.2kHz in bandwidth, but if it
> is spread spectrum within that 2.2kHz of bandwidth, it is illegal in the US
> below 1.2m.  It could be 500Hz in bandwidth, but if it uses SS, then it is
> illegal.
> 
> Is this the way it should be?  No.  Does it impede innovation and development
> of new mod es?  Yes.  However, the way the rule is written is what we have to
> follow.  Don't like it?  Then petition the FCC to modify part 97 to allow SS
> within a limited bandwidth (say 3 kHz).  As Skip has pointed out, there is a
> way to do this without mentioning ROS (or CHIP64/128) or any other SS mode.
> Quote the definition and petition for a modification, possibly with a
> bandwidth restriction, possibly without.  But, without changing the rule, the
> rest of the discussion is moot.
> 
> Dave
> K3DCW
> 
> 
> On Jul 13, 2010, at 2:23 PM, rein...@ix.netcom.com wrote:
> 
>>   
>> Hi Alan, 
>> 
>> Why did you wait so long with contributing here?
>> Please explain.
>> 
>> ++  In Feb of this year I quoted from the ARRL's Spread Spectrum Source book
>> page 5-2 ++
>> 
>> "  Spread Spectrum Fundamentals "
>> 
>> SS systems employ radio frequency bandwidths that greatly exceed the
>> bandwidth necessary
>> to convey the intelligence.
>> 
>> Bandwidths for SS systems generally run from 10 to 100 times the information
>> rate.
>> 
>> etc etc.
>> 
>> I got shouted out of the Group by addressing the use of ROS in the US by the
>> experts on
>> SS.
> 
> 
> Dave
> K3DCW
> www.k3dcw.net 
> 
>  
>
> 
> 

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Alan Barrow]

rein...@ix.netcom.com wrote:
> Hi Alan, 
>
> Why did you wait so long with contributing here?
> Please explain.

Hello Rein,

I've posted on this subject several times in the past with ITU & IEEE
references as well.

It does seem to get lost in the noise at times.

It does not help at all that the ROS author was doing much to incite
hatred toward the mode, which unfortunately flows over to anything that
looks/smells like ROS. (Specifically SS'ish type modes)

The most problematic aspects are the way the whole dialog about ROS as
handled are:

- Overly simplistic tests/definitions on an already poorly defined (from
FCC reg perspective) mode

- Simplistic bandwidth comparisons that do not factor in total
throughput. (IE: The effect of processor gain, FEC, etc). I don't think
ROS was stellar here, but the idea that a wider mode for X data rate is
worse than a narrower mode is flawed. Otherwise we'd all be using RTTY.
FEC increases bandwidth for the same data rate, but the trade off
surfaces over sustained measurement in real (difficult) HF conditions.
Skip's work did show there was not a big win for ROS, so we arrived at
the right spot. But many were banning just because it was wider than
their favorite mode!

- Lack of consideration that multiple SS signals could occupy the same
spectrum, effectively decreasing the total required bandwidth. There is
a point of diminishing returns, and ROS may not fare well. But if I
could stack a dozen or more data signals simultaneously in a single SSB
width slot, would that be a bad thing? Or what if a AF type SS (AFSS?)
mode could live on a non-interference basis, should it be banned just
because it was technically SS? No testing was done that I'm aware of
that would have allowed real world throughput to be measured with
multiple signals on the same channel. This is one of the big wins of DSSS!

- Assumption that the current FCC reg is the end all. It was accurate
for state of the art when added. But no one foresaw that DSP's would
allow an audio based SS implementation inside a SSB bandwidth. The FCC
reg was written to address the then current DSSS modems which used
spreading factors of 100x with direct IF injection, etc. And are totally
inappropriate for HF usage. Put another way, most professional RF
engineers would consider any audio based scheme to not be DSSS as it's
just not how it's done. Pretty much all real world DSSS systems use IF
level modulation to the point that it's one of the main identifying
characteristics.

- Very inappropriate involvement of the FCC. This is absolutely not the
way to approach a new mode, the answer is nearly always "check the regs".

One thing we can probably all agree on is that ROS is pretty much dead
for consideration in the US. The waters are too muddied at this point.

I'm more concerned about impact to the next innovation.

And the fact that all the noise & behavior set aside, the author did
implement something new that should have been evaluated on it's merits
before declared illegal via trial by yahoogroup. (Before he hastened
it's demise due to his own unprofessional behavior).

Personally, this episode just cements my believe that the US will be
trapped using legacy modes & arcane restrictions for the most part until
some form of bandwidth based bandplan approach is implemented like much
of the civilized world.

Lest we crow about some of the more recent innovations, we have to
factor in that rtty still rules the airwaves from a number of users and
usage perspective.

And it's about as inefficient a mode we could come up with when impact
to the spectrum is factored in. (medium power, wide sidebands, single
user per channel, etc). Call me when there is a weekend with as many PSK
signals on the air as one of the (too frequent) RTTY contests.

I'm not opposed to RTTY, exactly the opposite. But it's the RTTY centric
regs that hamper our development. Even things like P3 & winmor are
having to go the long way around to maximize performance while not
running afoul of the arcane RTTY based regs. (Much less use of tech like
the FS-1052 modems, etc)

Have fun,

Alan
km4ba

Re: [digitalradio] Re: Random data vs Spread Spectrum

[J. Moen]

There's the generally accepted definition of SS, quoted below and referring to 
bandwidths greatly exceeding what's necessary, and then there's the way the FCC 
regs are written, which do not refer to that definition.  

I think just about everyone, or maybe absolutely everyone who cares about the 
FCC regs, thinks in this case they are inappropriate, but the fact is, they do 
not allow for narrow-band SS, even though it would cause no real harm.  

The regs should be changed, but until they are, we in the US can not use SS 
below 220, or we can move to another country, or we can violate the regs, 
and/or we can campaign to change them.  But saying you don't agree with a law 
so you don't have to follow it is not the right way.

  Jim - K6JM

  - Original Message - 
  From: rein...@ix.netcom.com 
  To: digitalradio@yahoogroups.com 
  Sent: Tuesday, July 13, 2010 11:23 AM
  Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum 
  Hi Alan, 

  Why did you wait so long with contributing here?
  Please explain.

  ++ In Feb of this year I quoted from the ARRL's Spread Spectrum Source book 
page 5-2 ++

  " Spread Spectrum Fundamentals "

  SS systems employ radio frequency bandwidths that greatly exceed the 
bandwidth necessary
  to convey the intelligence.

  Bandwidths for SS systems generally run from 10 to 100 times the information 
rate.

  etc etc.

  I got shouted out of the Group by addressing the use of ROS in the US by the 
experts on
  SS.

  73 Rein W6SZ

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Dave Wright]

I think that a lot of people are missing the point with ROS and Spread Spectrum 
here in the US.

The author defined it as Spread Spectrum, only changing it to FSK144 (or 
whatever) after being told that SS was not allowed below 1.25m in the US.  The 
FCC rules don't mention bandwidth in relationship to SS, they don't say that it 
"must employ bandwidths that greatly exceed the bandwidth necessary to convey 
the intelligence", nor do they reference any Wikipedia/ARRL/RSGB/ITU or other 
organization's definition.  They simply mention SS as not being allowed below 
1.25m.  So, you can say that it is only 2.2kHz in bandwidth, but if it is 
spread spectrum within that 2.2kHz of bandwidth, it is illegal in the US below 
1.2m.  It could be 500Hz in bandwidth, but if it uses SS, then it is illegal.

Is this the way it should be?  No.  Does it impede innovation and development 
of new modes?  Yes.  However, the way the rule is written is what we have to 
follow.  Don't like it?  Then petition the FCC to modify part 97 to allow SS 
within a limited bandwidth (say 3 kHz).  As Skip has pointed out, there is a 
way to do this without mentioning ROS (or CHIP64/128) or any other SS mode.  
Quote the definition and petition for a modification, possibly with a bandwidth 
restriction, possibly without.  But, without changing the rule, the rest of the 
discussion is moot. 

Dave
K3DCW


On Jul 13, 2010, at 2:23 PM, rein...@ix.netcom.com wrote:

> Hi Alan, 
> 
> Why did you wait so long with contributing here?
> Please explain.
> 
> ++ In Feb of this year I quoted from the ARRL's Spread Spectrum Source book 
> page 5-2 ++
> 
> " Spread Spectrum Fundamentals "
> 
> SS systems employ radio frequency bandwidths that greatly exceed the 
> bandwidth necessary
> to convey the intelligence.
> 
> Bandwidths for SS systems generally run from 10 to 100 times the information 
> rate.
> 
> etc etc.
> 
> I got shouted out of the Group by addressing the use of ROS in the US by the 
> experts on
> SS.
> 
> 

Dave
K3DCW
www.k3dcw.net

Re: [digitalradio] Re: Random data vs Spread Spectrum

[KH6TY]

Rein,

I said I would not comment further on ROS, but look at it in 
perspective. The author defined ROS as spread spectrum and produced a 
two page document to that effect. He is the only one who knows for sure 
if it is spread spectrum or not.


When it was posted that spread spectrum was not legal below 222 Mhz, he 
conveniently (for his benefit) tried to redefine ROS as FSK, in an 
apparent attempt to change the FCC opinion, which originally was based 
on his own two-page declaration, which he wanted us to believe.


The FCC then made their own analysis and concluded it was not FSK but 
truly spread spectrum. This was communicated to us by the ARRL as is 
usually the case.


The author, if he would have disclosed his code, could have  proven 
whether or not  the  randomization is for spread spectrum purposes or 
for some other reason, but he steadfastly refused to disclose the code, 
which would either have resulted in it being OK for us to use, or prove 
it was truly FHSS. Perhaps he decided to try and bluff the FCC because 
it would be determined, on the basis of his code, to really be FHSS, in 
agreement with his first description, and in disagreement with the 
second description he wrote, obviously just to try to get approval.


It is just not reasonable to think that a person of his ability, as the 
author of the software, could make such a huge mistake in his first 
characterization of
ROS as spread spectrum and then completely revise the characterization 
as something else which he knew would be usable by US hams.


You can imagine how the FCC feels about that attempted deception, and to 
top it off, he posts a phoney statement of FCC approval besides! I 
seriously doubt that the FCC is going to want to revisit the question, 
since the author simply cannot be believed. I met Dan Henderson at a 
hamfest right after all this happened and he had been in contact the 
FCC, and opined that it was highly doubtful that any further 
reconsideration would be done.


The ONLY way for us to ever use ROS on HF is to petition the FCC to 
amend the rules to allow limited spread spectrum below 222 Mhz, citing 
enough good reasons why it will not harm existing operations of lesser 
bandwidth.


Instead of constantly arguing that the FCC made a mistake, or we should 
interpret the rules as we wish they were, I suggest that either a 
petition be filed, or the code released to prove the author's contention 
that it is not spread spectrum. Of course the submitted code would have 
to be recompiled and tested to prove it is really the original code, and 
another attempted deception by the author.


Understand that I am NOT "against" ROS, and never have been, even though 
I strongly dislike the author's behavior and suspect his motives. I 
would keep using it on HF if it were legal for me to do so. I do respect 
the FCC regulations, even those that I do not like, and follow them as 
best I can, because in the overall picture, they protect the weak from 
the strong for the benefit of everyone, until revised in a non-harmful way.


This will be my (final) final word on this subject, so please do not ask 
me to comment any further.


If you want to use ROS on HF, then enter a petition to get the 
regulations changed so you can, or work with someone else who will do 
that for you, and end this endless denigrating of the FCC, ARRL, and 
others who follow the regulations and depend upon ARRL interpretations 
of the FCC regulations for us all.


Signing off on ROS now -

73,  Skip KH6TY

On 7/13/2010 2:23 PM, rein...@ix.netcom.com wrote:


Hi Alan,

Why did you wait so long with contributing here?
Please explain.

++ In Feb of this year I quoted from the ARRL's Spread Spectrum Source 
book page 5-2 ++


" Spread Spectrum Fundamentals "

SS systems employ radio frequency bandwidths that greatly exceed the 
bandwidth necessary

to convey the intelligence.

Bandwidths for SS systems generally run from 10 to 100 times the 
information rate.


etc etc.

I got shouted out of the Group by addressing the use of ROS in the US 
by the experts on

SS.

73 Rein W6SZ

-Original Message-
>From: Alan Barrow mailto:ml9003%40pinztrek.com>>
>Sent: Jul 13, 2010 1:22 PM
>To: digitalradio@yahoogroups.com <mailto:digitalradio%40yahoogroups.com>
>Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum
>
>graham787 wrote:
>> So, if bits are added to the transmit waveform that are not 
performing a function of helping to re-create an error free 
replication of the input data, it meets my test as spread spectrum. If 
the symbols in the transmit waveform cannot be predicted by the 
previous sequence of bits over time at the input, it also would meet 
my test as spread spectrum. To reiterate on this point, just because 
the symbols of the transmit waveform are changing during an unchanging 
input, does not imply spread spectrum.

>>
>> Instead, they may

Re: [digitalradio] Re: Random data vs Spread Spectrum

[rein0zn]

Hi Alan, 

Why did you wait so long with contributing here?
Please explain.

++  In Feb of this year I quoted from the ARRL's Spread Spectrum Source book 
page 5-2 ++

"  Spread Spectrum Fundamentals "

SS systems employ radio frequency bandwidths that greatly exceed the bandwidth 
necessary
to convey the intelligence.

Bandwidths for SS systems generally run from 10 to 100 times the information 
rate.


etc etc.

I got shouted out of the Group by addressing the use of ROS in the US by the 
experts on
SS.

73 Rein W6SZ


-Original Message-
>From: Alan Barrow 
>Sent: Jul 13, 2010 1:22 PM
>To: digitalradio@yahoogroups.com
>Subject: Re: [digitalradio] Re: Random data vs Spread Spectrum
>
>graham787 wrote:
>> So, if bits are added to the transmit waveform that are not performing a 
>> function of helping to re-create an error free replication of the input 
>> data, it meets my test as spread spectrum. If the symbols in the transmit 
>> waveform cannot be predicted by the previous sequence of bits over time at 
>> the input, it also would meet my test as spread spectrum. To reiterate on 
>> this point, just because the symbols of the transmit waveform are changing 
>> during an unchanging input, does not imply spread spectrum. 
>>
>> Instead, they may well be the result of a defined randomizer process 
>> followed by multiple layers of FEC and modulation coding.
>>   
>
>While I do not support ROS in any form, I think the group is on a very
>slippery slope here with well intentioned but misinformed definitions &
>tests that may haunt us in the future!
>
>Just the fact that data is randomized does not define SS. There has to
>be a spreading factor, which has some rough definitions  based on
>practical applications, but is not addressed in any FCC definitions.
>
>Skip's well intentioned but overly simplistic test of looking at the bit
>stream is not enough to define SS. There are many legitimate reasons to
>code data resulting in a pseudo-random fashion that have nothing to do
>with SS!
>
>The most common is coding so the transitions between bit's can easily be
>detected even in noise. It's a problem when sequential bits look the same.
>
>You can also factor in FEC. There are many, many writeups on
>convolutional encoding that go into this. (Viterbi & reed-solomon are in
>wide usage)
>
>But it's also useful to spread the energy out in the bandwidth and avoid
>sidebands created by single tones of long duration. There are multiple
>modem/modes which do this, some in very wide usage.
>
>So yes, SS (really DSSS) is pseudo-random. But not all pseudo-random
>coding is SS, and we should not be proposing that as a litmus test!
>
>The real test should be:
>- direct or BPSK modulation via a pseudo-random code in addition to any
>coding for FEC (convolutional, etc)
>- A spreading factor significantly higher than the original data rate
>
>The 2nd item is the key part, and it's listed but virtually never quoted
>in this group, but is listed in nearly all the SS definitions. Nor is it
>addressed in the FCC part 97 rules.
>
>It's not enough that the bandwidth is higher than the data rate would
>imply, as nearly all modes with FEC would fail that by definition.
>
>The key is the "significantly wider" aspect, also referred to in
>ITU/IEEE definitions as "typically orders of magnitude greater than the
>data rate". And this is why many engineers question whether any SSB
>generated mode could be "real" SS. ROS only did it by having the
>original data rate lower than the SSB bandwidth.
>
>About the lowest commercial DSSS implementations use a spreading factor
>of 16:1, and that's for consumer grade without noise performance concerns.
>
>Most DSSS implementations in the real world use spreading factors of 100
>or greater, as that's when you start seeing significant noise recovery
>improvements.
>
>In DSSS, the "processor gain" which improves noise resilience is
>directly related to the spreading factor.
>
>I've posted multiple definitions from the ITU & IEEE in the past for
>DSSS. Wikipedia, which has some good information, does not constitute a
>formal definition like the ITU & IEEE references do. (Part of the reason
>that wikipedia is not admissible as sources for college & research papers).
>
>There is no shortage of formal definitions, we should not have to invent
>our own. There are also some very readable definitions from mfg's for
>their DSSS components.  Like this one:
>< http://www.maxim-ic.com/app-notes/index.mvp/id/1890 >
>
>
>So ROS (RIP) is very odd in this aspect, as it's nowhere near
>

Re: [digitalradio] Re: Random data vs Spread Spectrum

[Alan Barrow]

graham787 wrote:
> So, if bits are added to the transmit waveform that are not performing a 
> function of helping to re-create an error free replication of the input data, 
> it meets my test as spread spectrum. If the symbols in the transmit waveform 
> cannot be predicted by the previous sequence of bits over time at the input, 
> it also would meet my test as spread spectrum. To reiterate on this point, 
> just because the symbols of the transmit waveform are changing during an 
> unchanging input, does not imply spread spectrum. 
>
> Instead, they may well be the result of a defined randomizer process followed 
> by multiple layers of FEC and modulation coding.
>   

While I do not support ROS in any form, I think the group is on a very
slippery slope here with well intentioned but misinformed definitions &
tests that may haunt us in the future!

Just the fact that data is randomized does not define SS. There has to
be a spreading factor, which has some rough definitions  based on
practical applications, but is not addressed in any FCC definitions.

Skip's well intentioned but overly simplistic test of looking at the bit
stream is not enough to define SS. There are many legitimate reasons to
code data resulting in a pseudo-random fashion that have nothing to do
with SS!

The most common is coding so the transitions between bit's can easily be
detected even in noise. It's a problem when sequential bits look the same.

You can also factor in FEC. There are many, many writeups on
convolutional encoding that go into this. (Viterbi & reed-solomon are in
wide usage)

But it's also useful to spread the energy out in the bandwidth and avoid
sidebands created by single tones of long duration. There are multiple
modem/modes which do this, some in very wide usage.

So yes, SS (really DSSS) is pseudo-random. But not all pseudo-random
coding is SS, and we should not be proposing that as a litmus test!

The real test should be:
- direct or BPSK modulation via a pseudo-random code in addition to any
coding for FEC (convolutional, etc)
- A spreading factor significantly higher than the original data rate

The 2nd item is the key part, and it's listed but virtually never quoted
in this group, but is listed in nearly all the SS definitions. Nor is it
addressed in the FCC part 97 rules.

It's not enough that the bandwidth is higher than the data rate would
imply, as nearly all modes with FEC would fail that by definition.

The key is the "significantly wider" aspect, also referred to in
ITU/IEEE definitions as "typically orders of magnitude greater than the
data rate". And this is why many engineers question whether any SSB
generated mode could be "real" SS. ROS only did it by having the
original data rate lower than the SSB bandwidth.

About the lowest commercial DSSS implementations use a spreading factor
of 16:1, and that's for consumer grade without noise performance concerns.

Most DSSS implementations in the real world use spreading factors of 100
or greater, as that's when you start seeing significant noise recovery
improvements.

In DSSS, the "processor gain" which improves noise resilience is
directly related to the spreading factor.

I've posted multiple definitions from the ITU & IEEE in the past for
DSSS. Wikipedia, which has some good information, does not constitute a
formal definition like the ITU & IEEE references do. (Part of the reason
that wikipedia is not admissible as sources for college & research papers).

There is no shortage of formal definitions, we should not have to invent
our own. There are also some very readable definitions from mfg's for
their DSSS components.  Like this one:
< http://www.maxim-ic.com/app-notes/index.mvp/id/1890 >


So ROS (RIP) is very odd in this aspect, as it's nowhere near
conventional DSSS implementations in it's spreading factor, yet is
higher than the spreading seen by FEC & convolutional encoding. This is
a constraint of the AFSK/SSB encoding, but does pose some questions as
to how it should be treated.

In all the discussion of SS, bandwidth, etc, everyone is missing the
point that DSSS wider bandwidth usage is offset by use of CDMA.
(collision detection multiple access). DSSS is nearly always used with
many stations on the same "channel" with the same key. It's no accident
that cellular went from analog techniques to DSSS. it maximizes use
of their spectrum!

So the idea of ROS having multiple net frequencies is just silly, all
ROS stations should be using the same frequency! For that matter, so
should most of our advanced modes including winmor, ALE, etc. And we
have to factor in the fact that multiple stations could/should be using
the same spectrum when you examine bandwidth of DSSS.

Set aside all the unprofessional behavior by the pro & anti ROS
contingents...

I believe ROS as implemented did not offer enough processing  gain to
justify usage on crowded bands like 40m. But I think we hams lost an
opportunity to experiment with new modes that had promis

RE: [digitalradio] Re: Random data vs Spread Spectrum

[Lester Veenstra]

So the question I closed with; Where did I QSB into the noise. How could I
improve. I think understanding the fundamentals will take out a lot of the
hocus pocus about some systems, and if we had more open source systems, let
the community mind advance the state of the art.

 

Lester B Veenstra  MØYCM K1YCM

  les...@veenstras.com

  m0...@veenstras.com

  k1...@veenstras.com

 

 

US Postal Address:

PSC 45 Box 781

APO AE 09468 USA

 

UK Postal Address:

Dawn Cottage

Norwood, Harrogate

HG3 1SD, UK

 

Telephones:

Office: +44-(0)1423-846-385

Home: +44-(0)1943-880-963 

Guam Cell: +1-671-788-5654

UK Cell:   +44-(0)7716-298-224 

US Cell:   +1-240-425-7335 

Jamaica:  +1-876-352-7504 

 

This e-mail and any documents attached hereto contain confidential or
privileged information. The information is intended to be for use only by
the individual or entity to whom they are addressed. If you are not the
intended recipient or the person responsible for delivering the e-mail to
the intended recipient, be aware that any disclosure, copying, distribution
or use of the contents of this e-mail or any documents attached hereto is
prohibited.

 

From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On
Behalf Of Alan
Sent: Monday, July 12, 2010 11:36 PM
To: digitalradio@yahoogroups.com
Subject: [digitalradio] Re: Random data vs Spread Spectrum

 

  



Yes, very good presentation and explanation...I actually understood it, well
kinda...73, Alan

RE: [digitalradio] Re: Random data vs Spread Spectrum

[Lester Veenstra]

Well I started out life as a Physicist, but had to specialize to find real
work HI  

 

 

 

Lester B Veenstra  MØYCM K1YCM

  les...@veenstras.com

  m0...@veenstras.com

  k1...@veenstras.com

 

 

US Postal Address:

PSC 45 Box 781

APO AE 09468 USA

 

UK Postal Address:

Dawn Cottage

Norwood, Harrogate

HG3 1SD, UK

 

Telephones:

Office: +44-(0)1423-846-385

Home: +44-(0)1943-880-963 

Guam Cell: +1-671-788-5654

UK Cell:   +44-(0)7716-298-224 

US Cell:   +1-240-425-7335 

Jamaica:  +1-876-352-7504 

 

This e-mail and any documents attached hereto contain confidential or
privileged information. The information is intended to be for use only by
the individual or entity to whom they are addressed. If you are not the
intended recipient or the person responsible for delivering the e-mail to
the intended recipient, be aware that any disclosure, copying, distribution
or use of the contents of this e-mail or any documents attached hereto is
prohibited.

 

From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On
Behalf Of Paul W. Ross
Sent: Monday, July 12, 2010 11:29 PM
To: digitalradio@yahoogroups.com
Subject: [digitalradio] Re: Random data vs Spread Spectrum

 

  

THAT was an EXCELLENT presentation!

THANKS! (and EE and Computer Scientist in an earlier life)

/paul W3FIS

RE: [digitalradio] Re: Random data vs Spread Spectrum

[rein0zn]

Hi Steve,

I was told this by a Section Manager. So what can I say. Have not been at HQ for
at least 10 yesrs.
The statement about ROS did not impress me as being pro radio amateur.
For me it was a passive transfer of information.
He was the spokesman for the ARRL.

There are very diverse opinions about this ruling, That much I know about it.

But he see that seldom expressed here, forget about discussing it on his 
technical merits.

( you just wanted to let us ( me ) know about Mr Henderson

I do not know Mr Hendersson, and had felt better if one of the lab people or Mr.
Summer had gotten involved.

Again and again if is it said "We don't classify, if the painter calls it a dog
and it looks like a cat, then we still call it a dog. 
It up to the viewer to determine what it is.
However, if he or she says it a cat , it violates the law."
How more crazy can it get?

Steve, what does this really has to do with this case?

I am sorry.

73 Rein W6SZ 

-Original Message-
>From: "Ford, Steve,  WB8IMY" 
>Sent: Jul 12, 2010 6:42 PM
>To: digitalradio@yahoogroups.com
>Subject: RE: [digitalradio] Re: Random data vs Spread Spectrum
>
>I normally just lurk on this list, but I wanted to jump in and make an 
>important clarification.
> 
>>Mr. Dan Henderson is a paid lawyer ( unusual for ARRL officials )
>>Enough said here. He is a liaison person for among other organizations, the 
>>FCC.
>>He communicates, does not ask questions
>
>Dan Henderson, N1ND, is not employed at ARRL Headquarters as an attorney. He 
>is our Regulatory Branch Manager, not an "official." (Officials are ARRL 
>corporate officers and Division Directors.) Dan only represents the ARRL in 
>his work, not other organizations.
> 
>You are probably confusing Dan with Chris Imlay, the ARRL General Counsel. 
>Chris *is* an attorney and represents the ARRL in that capacity before the FCC 
>and in other matters.
> 
>73 . . . 
> 
>Steve Ford, WB8IMY
>ARRL
>
> 
>
>
>From: Rein A [mailto:rein...@ix.netcom.com]
>Sent: Mon 7/12/2010 6:00 PM
>To: digitalradio@yahoogroups.com
>Subject: [digitalradio] Re: Random data vs Spread Spectrum
>
>
>  
>
>
>
>Hi Skip,
>
>I like to see this ruling revisited by technical personal
>within the FCC. The FCC, not ARRL. That's all.
>
>Mr. Dan Henderson is a paid lawyer ( unusual for ARRL officials )
>Enough said here. He is a liaison person for among other organizations, the 
>FCC.
>He communicates, does not ask questions
>
>I do not think and did not think the day it was made, it was
>done by the right person(s). What is "Is is up to the people etc
>we don't rule on the mode or its content/operation?"
>
>You and others here promoted the decision as in concrete. I think
>you and others like it to be so ( just an opinion )
>
>All the stupidity of Jose and now this cluster thing make
>revisiting harder and harder, if not impossible indeed.
>
>If the few of us here who are interested to use ROS had been
>united and not scared by the please lets move on crowd we could
>have been able to at least reconsider the situation.
>
>Therefore we all should force Jose to fix this and the users 
>outside the US should stop using it. Of course they are mot reading
>this or even part from this group.
>
>Clear and simple
>
>73 Rein W6SZ
>
>--- In digitalradio@yahoogroups.com <mailto:digitalradio%40yahoogroups.com> , 
>KH6TY  wrote:
>>
>> It was not my idea. The author wanted the FCC to say it was not spread 
>> spectrum. Unfortunately for all of us in the US, it is spread spectrum, 
>> and the FCC rules do not allow that below 222 MHz.
>> 
>> I am not potentially damaging the hobby as a whole, just posting what I 
>> know.
>> 
>> Go ahead and use ROS if you think you will be legal! You will do more 
>> damage to the hobby than anyone who refuses to use it, by flaunting the 
>> regulations.
>> 
>> 73, Skip KH6TY.
>> 
>> On 7/12/2010 1:52 PM, W2XJ wrote:
>> >
>> > Why do you persist in getting the FCC involved? You are potentially 
>> > damaging the hobby as a whole. If one is qualified to hold a license 
>> > the FCC presumes ones ability to determine what operations are legal.
>> >
>> >
>> > On 7/12/10 1:28 PM, "KH6TY" > wrote:
>> >
>> >
>> >
>> >
>> >
>> >
>> > Lester,
>> > The "inventor" has shown over and over that he is not to be
>> > trusted, and so his block diagram would not be believed either. I
>> > suggested months ago to him to just send his c

RE: [digitalradio] Re: Random data vs Spread Spectrum

[Ford, Steve, WB8IMY]

I normally just lurk on this list, but I wanted to jump in and make an 
important clarification.
 
>Mr. Dan Henderson is a paid lawyer ( unusual for ARRL officials )
>Enough said here. He is a liaison person for among other organizations, the 
>FCC.
>He communicates, does not ask questions

Dan Henderson, N1ND, is not employed at ARRL Headquarters as an attorney. He is 
our Regulatory Branch Manager, not an "official." (Officials are ARRL corporate 
officers and Division Directors.) Dan only represents the ARRL in his work, not 
other organizations.
 
You are probably confusing Dan with Chris Imlay, the ARRL General Counsel. 
Chris *is* an attorney and represents the ARRL in that capacity before the FCC 
and in other matters.
 
73 . . . 
 
Steve Ford, WB8IMY
ARRL

 


From: Rein A [mailto:rein...@ix.netcom.com]
Sent: Mon 7/12/2010 6:00 PM
To: digitalradio@yahoogroups.com
Subject: [digitalradio] Re: Random data vs Spread Spectrum


  



Hi Skip,

I like to see this ruling revisited by technical personal
within the FCC. The FCC, not ARRL. That's all.

Mr. Dan Henderson is a paid lawyer ( unusual for ARRL officials )
Enough said here. He is a liaison person for among other organizations, the FCC.
He communicates, does not ask questions

I do not think and did not think the day it was made, it was
done by the right person(s). What is "Is is up to the people etc
we don't rule on the mode or its content/operation?"

You and others here promoted the decision as in concrete. I think
you and others like it to be so ( just an opinion )

All the stupidity of Jose and now this cluster thing make
revisiting harder and harder, if not impossible indeed.

If the few of us here who are interested to use ROS had been
united and not scared by the please lets move on crowd we could
have been able to at least reconsider the situation.

Therefore we all should force Jose to fix this and the users 
outside the US should stop using it. Of course they are mot reading
this or even part from this group.

Clear and simple

73 Rein W6SZ

--- In digitalradio@yahoogroups.com  , 
KH6TY  wrote:
>
> It was not my idea. The author wanted the FCC to say it was not spread 
> spectrum. Unfortunately for all of us in the US, it is spread spectrum, 
> and the FCC rules do not allow that below 222 MHz.
> 
> I am not potentially damaging the hobby as a whole, just posting what I 
> know.
> 
> Go ahead and use ROS if you think you will be legal! You will do more 
> damage to the hobby than anyone who refuses to use it, by flaunting the 
> regulations.
> 
> 73, Skip KH6TY.
> 
> On 7/12/2010 1:52 PM, W2XJ wrote:
> >
> > Why do you persist in getting the FCC involved? You are potentially 
> > damaging the hobby as a whole. If one is qualified to hold a license 
> > the FCC presumes ones ability to determine what operations are legal.
> >
> >
> > On 7/12/10 1:28 PM, "KH6TY" > wrote:
> >
> >
> >
> >
> >
> >
> > Lester,
> > The "inventor" has shown over and over that he is not to be
> > trusted, and so his block diagram would not be believed either. I
> > suggested months ago to him to just send his code in confidence to
> > the FCC, which they would keep private, and be done with it. He
> > replied that, arrogantly, "The FCC would have to purchase the code
> > from him". To me, that suggests that he is unwilling to disclose
> > the code because it would prove once and for all that it was
> > spread spectrum, and instead, he tried to bluff his way to
> > approval, even by changing his original description of the code as
> > spread spectrum, which obviously did not work.
> >
> > ROS's best advantage, IMHO, is for EME, and it is legal there for
> > US hams for 432 and 1296 EME. I only wish it were legal on 2M also
> > and I could use it for EME on that band.
> >
> > Yes, it should be open-source, and that would end the discussion,
> > but he has (for perhaps devious or commercial) personal reasons
> > for refusing to do so.
> >
> > That is just not going to happen, so let's end the discussion on
> > that note and get on the air instead!
> >
> > 73, Skip KH6TY
> >
> > On 7/12/2010 1:14 PM, Lester Veenstra wrote:
> >
> >
> >
> >
> >
> > Skip:
> >
> > Spectral analysis cannot differentiate between a high
> > rate FEC operating after, as it invariably must, a randomizer,
> > and a true spread spectrum system. And a spread spectrum
> > system does not need to employ frequency hopping. And a signal
> > that "frequency hops" is not necessarily a spread spectrum
> > signal. I refer you to the old favorite of the UK Diplomatic
> > service, the Piccolo.
> >
> >
> >
> > As I advocated in an earlier post, the way to end this endless
> > discussion would be for the "inventor" to disclose the block
> > diagram of the various steps in his encoding/modulation
> > system. In fact I was rash enough to suggest that IMHO, all of
> > these systems being played with by hams, should be open
> > sourced, so t