[digitalradio] There is a pattern in the ROS signal when idling [1 Attachment]

2010-02-27 Thread Steinar Aanesland
Hi Skip

I have been monitoring a ROS idling over time using DL4YHF's Spectrum
Lab. Here is the results.You can clearly see a pattern

73 de LA5VNA Steinar





On 26.02.2010 12:29, KH6TY wrote:
 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 Of course, the FCC rules on SS are outdated and ROS should be allowed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






[digitalradio] Idling ROS pattern

2010-02-27 Thread Steinar Aanesland




Re: [digitalradio] Idling ROS pattern

2010-02-27 Thread Steinar Aanesland

Humm, I seems to have trouble with the attachment.
I hope you get this :


http://xa.yimg.com/kq/groups/1871183/sn/1267152391/name/ROS.jpg


73 de LA5VNA Steinar







[digitalradio] Idling ROS pattern repeat it self

2010-02-27 Thread Steinar Aanesland
And it clearly repeat it self

http://home.broadpark.no/~saanes/bilder/ROS2.jpg

73 de LA5VNA Steinar







On 27.02.2010 10:58, Steinar Aanesland wrote:
 Humm, I seems to have trouble with the attachment.
 I hope you get this :


 http://xa.yimg.com/kq/groups/1871183/sn/1267152391/name/ROS.jpg


 73 de LA5VNA Steinar






   




Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread KH6TY
That's a good analysis, Steinar. Is it possible to see if the pattern 
changes when sending data? That is all the FCC is concerned about. The 
pattern has to change when sending data and not just remain the same to 
exclude it from being FHSS.


73 - Skip KH6TY




Steinar Aanesland wrote:
 
[Attachment(s) #TopText from Steinar Aanesland included below]


Hi Skip

I have been monitoring a ROS idling over time using DL4YHF's Spectrum
Lab. Here is the results.You can clearly see a pattern

73 de LA5VNA Steinar

On 26.02.2010 12:29, KH6TY wrote:
 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







Re: [digitalradio] RTTY frequencies?

2010-02-27 Thread James French
On Tuesday 23 February 2010 11:27:21 you wrote:
 James, you will not have to LOOK.  This contest will bring out thousabds of
 RTTY ops and  80-40-20-15-10 will be full if those bands are open.  The
 ARRL band plan will be where you find them, but some operators will go
 higher,
 Andy K3UK

 

Thanks, Andy for the input.

If anyone is playing this weekend in the RTTY contest, look for W8PGW and say 
hi!!

James W8ISS




Try Hamspots, PSKreporter, and K3UK Sked Page 
http://www.obriensweb.com/skedpskr4.html
Suggesting calling frequencies: Modes 500Hz 3583,7073,14073,18103, 
21073,24923, 28123 .  Wider modes e.g. Olivia 32/1000, ROS16, ALE: 14109.7088.
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[digitalradio] Re: There is a pattern in the ROS signal when idling

2010-02-27 Thread pa0r
SS uses pseudorandom codes to wag the carrier(s).
EVERY pseudorandom code is repetitive, the length may vary.

73,

Rein PA0R

--- In digitalradio@yahoogroups.com, KH6TY kh...@... wrote:

 That's a good analysis, Steinar. Is it possible to see if the pattern 
 changes when sending data? That is all the FCC is concerned about. The 
 pattern has to change when sending data and not just remain the same to 
 exclude it from being FHSS.
 
 73 - Skip KH6TY
 
 
 
 
 Steinar Aanesland wrote:
   
  [Attachment(s) #TopText from Steinar Aanesland included below]
 
  Hi Skip
 
  I have been monitoring a ROS idling over time using DL4YHF's Spectrum
  Lab. Here is the results.You can clearly see a pattern
 
  73 de LA5VNA Steinar
 
  On 26.02.2010 12:29, KH6TY wrote:
   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
  
  
  
 
 





Re: [digitalradio] Re: There is a pattern in the ROS signal when idling

2010-02-27 Thread KH6TY

Thanks for the clarification, Rein.

That agrees with what Steinar sees, and with the Wikipedia discussion, 
which says in part, Most pseudorandom generator algorithms produce 
sequences which are uniformly distributed 
/wiki/Uniform_distribution_%28discrete%29 by any of several tests. It 
is an open question, and one central to the theory and practice of 
cryptography /wiki/Cryptography, whether there is any way to 
distinguish the output of a high-quality PRNG from a truly random 
sequence without knowing the algorithm(s) used and the state with which 
it was initialized.


The differentiating factor in FHSS is apparently whether or not the data 
is superimposed on the carriers, or if the carrier frequencies are 
determined by the data. I cannot see that happing in ROS, and I can in 
all the FSK modes, but maybe I just do not know how to find it for sure. 
I guess the FCC engineers will probably figure out if ROS is actually 
spread spectrum as originally claimed, or FSK with FEC as now claimed.


It is just hard to imagine that someone as intelligent and capable as 
Jose could make such a huge mistake after writing seven pages of text 
and diagrams describing the mode the first time! No wonder the FCC 
believed him! Will they now believe him, or will they believe that the 
so-called technical description now on the ROS website is just an 
attempt to get ROS considered legal on HF? Probably they will believe 
only their own tests now, so we will have to wait for those.


The FCC does not care about the mode, or what it is called, but only 
what is transmitted on the air.


73 - Skip KH6TY




pa0r wrote:
 


SS uses pseudorandom codes to wag the carrier(s).
EVERY pseudorandom code is repetitive, the length may vary.

73,

Rein PA0R

--- In digitalradio@yahoogroups.com 
mailto:digitalradio%40yahoogroups.com, KH6TY kh...@... wrote:


 That's a good analysis, Steinar. Is it possible to see if the pattern
 changes when sending data? That is all the FCC is concerned about. The
 pattern has to change when sending data and not just remain the same to
 exclude it from being FHSS.

 73 - Skip KH6TY




 Steinar Aanesland wrote:
 
  [Attachment(s) #TopText from Steinar Aanesland included below]
 
  Hi Skip
 
  I have been monitoring a ROS idling over time using DL4YHF's Spectrum
  Lab. Here is the results.You can clearly see a pattern
 
  73 de LA5VNA Steinar
 
  On 26.02.2010 12:29, KH6TY wrote:
   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.
  
   âEURoe/If/ it walks /like a duck/, quacks /like a duck/, /looks 
like a

   duck/, it must be a /duck/âEUR?.
  
   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
  
  
  
 
 





[digitalradio] Making RSID de rigueur, for Olivia

2010-02-27 Thread obrienaj
I want to embark on a campaign to make  RSID de rigueur, for Olivia.   It is 
nice to see Olivia continue to be used as a mode , a very effective mode.  
However, Olivia users need to remind themselves that there are 10 common  sets  
tones/bw,  and despite their appearance in a waterfall, it is not easy to 
determine which Olivia variant it is.  RS ID makes that so much easier.  Please 
use it, it will increase your chances of a someone returning to your CQ.

Andy K3UK



Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread Steinar Aanesland

Hi Skip

Here is the new ROS signal. It is idling with two gruops of 25 sec of
X's . As you can see the pattern change when sending data.

http://home.broadpark.no/~saanes/bilder/ROS_X_2.JPG

73 de LA5VNA Steinar






On 27.02.2010 13:19, KH6TY wrote:
 That's a good analysis, Steinar. Is it possible to see if the pattern
 changes when sending data? That is all the FCC is concerned about. The
 pattern has to change when sending data and not just remain the same
 to exclude it from being FHSS.

 73 - Skip KH6TY





Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread KH6TY
Looks like good news Steinar! If the data changes the frequencies, it 
does not qualify as FHSS as Jose originally claimed. I am sure the FCC 
will find the same during their tests and expect them to say it can be 
used on HF and VHF. I am especially interested in being able to use the 
1 baud mode for EME on 2m and right now, FHSS is not permitted below 222 
MHz. However, we will have to wait for the FCC to issue a new opinion, 
since they already issued one based on Jose's original claims.


73 - Skip KH6TY




Steinar Aanesland wrote:
 



Hi Skip

Here is the new ROS signal. It is idling with two gruops of 25 sec of
X's . As you can see the pattern change when sending data.

http://home.broadpark.no/~saanes/bilder/ROS_X_2.JPG 
http://home.broadpark.no/%7Esaanes/bilder/ROS_X_2.JPG


73 de LA5VNA Steinar

On 27.02.2010 13:19, KH6TY wrote:
 That's a good analysis, Steinar. Is it possible to see if the pattern
 changes when sending data? That is all the FCC is concerned about. The
 pattern has to change when sending data and not just remain the same
 to exclude it from being FHSS.

 73 - Skip KH6TY





[digitalradio] Evidence that ROS is not true Spread Spectrum

2010-02-27 Thread obrienaj
This thread now appears to confirm what Jose and a few others have claimed 
.That ROS has some characteristics of Spread Spectrum and frequency hopping, 
but does not meet the definition that the FCC has implied when not allowing 
Spread Spectrum in the USA.  The hams involved in this thread (Skip, Rein, and 
Steinar) , are well known for their technical knowledge.  So, although some 
hams may wish to wait for more definitive  opinions from the  ARRL and/or FCC, 
this might be used as reasonable evidence that use on the appropriate parts of 
the HF is OK for the USA . 

Thanks to the hams that did some good technical investigation, and thanks to 
Jose for his substantial contribution to ham radio.

Andy K3UK

--- In digitalradio@yahoogroups.com, KH6TY kh...@... wrote:

 Looks like good news Steinar! If the data changes the frequencies, it 
 does not qualify as FHSS as Jose originally claimed. I am sure the FCC 
 will find the same during their tests and expect them to say it can be 
 used on HF and VHF. I am especially interested in being able to use the 
 1 baud mode for EME on 2m and right now, FHSS is not permitted below 222 
 MHz. However, we will have to wait for the FCC to issue a new opinion, 
 since they already issued one based on Jose's original claims.
 
 73 - Skip KH6TY
 
 
 
 
 Steinar Aanesland wrote:
   
 
 
  Hi Skip
 
  Here is the new ROS signal. It is idling with two gruops of 25 sec of
  X's . As you can see the pattern change when sending data.
 
  http://home.broadpark.no/~saanes/bilder/ROS_X_2.JPG 
  http://home.broadpark.no/%7Esaanes/bilder/ROS_X_2.JPG
 
  73 de LA5VNA Steinar
 
  On 27.02.2010 13:19, KH6TY wrote:
   That's a good analysis, Steinar. Is it possible to see if the pattern
   changes when sending data? That is all the FCC is concerned about. The
   pattern has to change when sending data and not just remain the same
   to exclude it from being FHSS.
  
   73 - Skip KH6TY
  
 
 





Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread Dave Ackrill
KH6TY wrote:
 Looks like good news Steinar! If the data changes the frequencies, it 
 does not qualify as FHSS as Jose originally claimed. I am sure the FCC 
 will find the same during their tests and expect them to say it can be 
 used on HF and VHF.

When they do, please let me know so that I can let people over here who 
have only read the 'it's illegal in the USA' message know.

Thanks - Dave (G0DJA)


[digitalradio] Screenshot: HRD-SDR-DM780 sync'd

2010-02-27 Thread Andy obrien
http://www.obriensweb.com/hrdsdr.jpg

FYI, SDR-IQ,,  TS2000, SpectraVue, HRD, DM780 all fully  sync'd and interfaced.

Andy K3UK


Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread Steinar Aanesland
Hi Skip

First ,  I have read all of your mail's and I think you have argued fair
and square.
I can't tell if ROS is FHSS or not . This is to complicate for a country
boy like me, but  I really hope that  FCC will let you use narrow band
 SS on HF some day .

Cross my fingers for you and 73
LA5VNA Steinar


 
 


On 27.02.2010 18:21, KH6TY wrote:
 Looks like good news Steinar! If the data changes the frequencies, it
 does not qualify as FHSS as Jose originally claimed. I am sure the FCC
 will find the same during their tests and expect them to say it can be
 used on HF and VHF. I am especially interested in being able to use
 the 1 baud mode for EME on 2m and right now, FHSS is not permitted
 below 222 MHz. However, we will have to wait for the FCC to issue a
 new opinion, since they already issued one based on Jose's original
 claims.

 73 - Skip KH6TY




 Steinar Aanesland wrote:
  


 Hi Skip

 Here is the new ROS signal. It is idling with two gruops of 25 sec of
 X's . As you can see the pattern change when sending data.

 http://home.broadpark.no/~saanes/bilder/ROS_X_2.JPG
 http://home.broadpark.no/%7Esaanes/bilder/ROS_X_2.JPG

 73 de LA5VNA Steinar

 On 27.02.2010 13:19, KH6TY wrote:
  That's a good analysis, Steinar. Is it possible to see if the pattern
  changes when sending data? That is all the FCC is concerned about. The
  pattern has to change when sending data and not just remain the same
  to exclude it from being FHSS.
 
  73 - Skip KH6TY
 







[digitalradio] Re: Making RSID de rigueur, for Olivia

2010-02-27 Thread Gavin
Agreed, it is handy for all digi modes.except psk31..why do people 
insist on using RSID for modes we all know?
It gets damned annoying seeing little boxes popping up on my screen to tell me 
it has heard a psk31 signal.Qpsk even i could accept, but psk31  using 
rsid for psk31 is just dumb.

So just use it for the more exotic modes please!

--- In digitalradio@yahoogroups.com, obrienaj k3uka...@... wrote:

 I want to embark on a campaign to make  RSID de rigueur, for Olivia.   It is 
 nice to see Olivia continue to be used as a mode , a very effective mode.  
 However, Olivia users need to remind themselves that there are 10 common  
 sets  tones/bw,  and despite their appearance in a waterfall, it is not easy 
 to determine which Olivia variant it is.  RS ID makes that so much easier.  
 Please use it, it will increase your chances of a someone returning to your 
 CQ.
 
 Andy K3UK





[digitalradio] Re: Making RSID de rigueur, for Olivia

2010-02-27 Thread obrienaj
Gavin,  what software are u using ?  Mine (Multipsk) can be set to allow RS ID 
by modes...  I can exclude BPSK31 RS ID alerts.

Andy K3UK

--- In digitalradio@yahoogroups.com, Gavin g0...@... wrote:

 Agreed, it is handy for all digi modes.except psk31..why do people 
 insist on using RSID for modes we all know?
 It gets damned annoying seeing little boxes popping up on my screen to tell 
 me it has heard a psk31 signal.Qpsk even i could accept, but psk31  
 using rsid for psk31 is just dumb.
 
 So just use it for the more exotic modes please!
 
 --- In digitalradio@yahoogroups.com, obrienaj k3ukandy@ wrote:
 
  I want to embark on a campaign to make  RSID de rigueur, for Olivia.   It 
  is nice to see Olivia continue to be used as a mode , a very effective 
  mode.  However, Olivia users need to remind themselves that there are 10 
  common  sets  tones/bw,  and despite their appearance in a waterfall, it is 
  not easy to determine which Olivia variant it is.  RS ID makes that so much 
  easier.  Please use it, it will increase your chances of a someone 
  returning to your CQ.
  
  Andy K3UK
 





Re: [digitalradio] Does ROS spectrum match the specification?

2010-02-27 Thread John B. Stephensen
A new technical description was published so you should see what it describes 
-- fixed start and stop sequences using 16 tones with convolutionally coded 
data using 128 tones in between.

73,

John
KD6OZH

  - Original Message - 
  From: Steinar Aanesland 
  To: digitalradio@yahoogroups.com 
  Sent: Saturday, February 27, 2010 16:48 UTC
  Subject: Re: [digitalradio] There is a pattern in the ROS signal when idling




  Hi Skip

  Here is the new ROS signal. It is idling with two gruops of 25 sec of
  X's . As you can see the pattern change when sending data.

  http://home.broadpark.no/~saanes/bilder/ROS_X_2.JPG

  73 de LA5VNA Steinar

  .
   
  

Re: [digitalradio] There is a pattern in the ROS signal when idling

2010-02-27 Thread John B. Stephensen
The FCC will say that it up to each licensee to check the legality by reading 
the new technical specification. Unless someone shows that the spectrum doesn't 
match the specification U.S.hams should feel safe using ROS.

73,

John
KD6OZH

  - Original Message - 
  From: Dave Ackrill 
  To: digitalradio@yahoogroups.com 
  Sent: Saturday, February 27, 2010 17:31 UTC
  Subject: Re: [digitalradio] There is a pattern in the ROS signal when idling



  KH6TY wrote:
   Looks like good news Steinar! If the data changes the frequencies, it 
   does not qualify as FHSS as Jose originally claimed. I am sure the FCC 
   will find the same during their tests and expect them to say it can be 
   used on HF and VHF.

  When they do, please let me know so that I can let people over here who 
  have only read the 'it's illegal in the USA' message know.

  Thanks - Dave (G0DJA)


  

[digitalradio] Spectrum Spreading

2010-02-27 Thread Rud Merriam
I avoided most of the discussion in the last week or so but finally decided
to see what the ARRL Handbook had to say. At first I thought it was totally
unhelpful but after it sank in a bit found it some help. 

What I gleaned is that many digital modes use spectrum spreading techniques.
The handbook seemed quite clear on this point. I am still trying to
understand what spectrum spreading means. There is an implication in there
of using more spectrum than.… something. 

For analog, i.e. voice, this is somewhat clear. If you are sending voice up
to 2.5kz then the spectrum 'something' is around 2.5 kHz SSB, or double that
for AM. Spectrum spreading would utilize some additional spectrum. Consider
a hypothetical mode where you took the voice signal, spread the audio by 4
times to generate a 10 kHz signal, and used that audio to modulate the RF.
That would be a spectrum spreading technique. 

I simply cannot get a handle on what spreading means for a digital signal.
Is the base 'something' CW and PSK31? 

From the Handbook, and I gather from the discussion here, there is another
aspect which concerns the way in which the signal is encoded. In my
hypothetical analog mode you might somehow invert or fold the frequency
spectrum. The reverse technique would be required to decode the signal. It
is my sense that some types of encoding are not allowed, while others would
be acceptable. 

Not trying to start the entire debate but hoping to get a better
understanding of the meaning of all this. 

 
 - 73 - 
Rud Merriam K5RUD 
ARES AEC Montgomery County, TX
http://mysticlakesoftware.com/



[digitalradio] New subject: FSK clicks

2010-02-27 Thread jhaynesatalumni
I was just listening on 80M - some kind of RTTY contest is on - and
I hear a bunch of normal-sounding FSK RTTY signals, and some that
are awfully clicky, like key clicks except it's FSK.  I wonder what
those guys are doing wrong.  Having the speech processor turned on,
perhaps?  Or too-rapid switching between mark and space?  Please
listen when you get a chance and see if you hear what I'm hearing
and if you can guess what is causing it.  On the waterfall it shows
up kinda like an overdriven PSK signal, but that shouldn't matter
so much for FSK.

Jim W6JVE



Re: [digitalradio] Spectrum Spreading

2010-02-27 Thread John Becker, WØJAB
Text deleted for a very good reason...

And some complained about pactor. Or Amtor.

John, W0JAB






Re: [digitalradio] Spectrum Spreading

2010-02-27 Thread John B. Stephensen
Chapter 8 of the 2010 handbook has a short overview of spread-spectrum 
techniques that could be applied to either analog or digital modulation. The 
original signal cold be anything (BPSK, FSK, FM...) and is phase or frequency 
modulated by a pseudorandom sequence in order to spread the signal over a wider 
range of frequencies. In frequency hopping spread spectrum (FHSS) the receiver 
and transmitter just shift between a predefined set of frequenies during the 
transmission. Direct sequence spread-spectrum (DSSS) applies an additional 
level of phase modulation with a pseudorandom sequence to spread the original 
signal over a wider range of frequencies. DSSS often just exclusive-ORs 
(modulo-2 adds) the data with a spreading sequence at a rate that is a multiple 
of the original symbol rate.

Error-correcting codes sometimes increase the bandwidth of a signal, but they 
do so by increasing the redundancy in the original signal. This could just be 
sending additional copies of the original data or adding parity bits to the 
data in block codes or multiplying the current data values with previous data 
values in convolutional coding. For example the current data value could be 
added to the previous two values and interleaved with the current value added 
to the second previous value.   

73,

John
KD6OZH

  - Original Message - 
  From: Rud Merriam 
  To: digitalradio@yahoogroups.com 
  Sent: Sunday, February 28, 2010 00:11 UTC
  Subject: [digitalradio] Spectrum Spreading




  I avoided most of the discussion in the last week or so but finally decided 
to see what the ARRL Handbook had to say. At first I thought it was totally 
unhelpful but after it sank in a bit found it some help. 

  What I gleaned is that many digital modes use spectrum spreading techniques. 
The handbook seemed quite clear on this point. I am still trying to understand 
what spectrum spreading means. There is an implication in there of using more 
spectrum than.. something. 

  For analog, i.e. voice, this is somewhat clear. If you are sending voice up 
to 2.5kz then the spectrum 'something' is around 2.5 kHz SSB, or double that 
for AM. Spectrum spreading would utilize some additional spectrum. Consider a 
hypothetical mode where you took the voice signal, spread the audio by 4 times 
to generate a 10 kHz signal, and used that audio to modulate the RF. That would 
be a spectrum spreading technique. 

  I simply cannot get a handle on what spreading means for a digital signal. Is 
the base 'something' CW and PSK31? 

  From the Handbook, and I gather from the discussion here, there is another 
aspect which concerns the way in which the signal is encoded. In my 
hypothetical analog mode you might somehow invert or fold the frequency 
spectrum. The reverse technique would be required to decode the signal. It is 
my sense that some types of encoding are not allowed, while others would be 
acceptable. 

  Not trying to start the entire debate but hoping to get a better 
understanding of the meaning of all this. 

   
   - 73 - 
  Rud Merriam K5RUD
  ARES AEC Montgomery County, TX 
  http://mysticlakesoftware.com/