Re: [digitalradio] Re: Random data vs Spread Spectrum
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 SSB phone stations, or
[digitalradio] Re: Random data vs Spread Spectrum
--- In digitalradio@yahoogroups.com, J. Moen j...@... 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
[digitalradio] Re: Random data vs Spread Spectrum
--- In digitalradio@yahoogroups.com, Alan Barrow ml9...@... wrote: 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. I think that before any new mode should be made available for general use, the developer(s) should have some acceptable plan for where it will be used. In Jose's defense, no such system exists for finding or allocating frequencies. He asked users, hams, to suggest frequencies that could be used, on the assumption that they were the experts on this. Unfortunately the people he asked were ignorant of any band usage other than the modes they personally used, so the frequencies they suggested were ones used by beacons, packet networks etc. 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. :-) Unfortunately, we are constrained (you in the USA I believe are legally constrained) by band planning drawn up in the days when there were no digital modes wider than RTTY. If people were free to use ROS in the part of the band where other wide band modes are used then the ill feeling that was caused by the mode would probably have been avoided. Perhaps when petitioning the FCC to allow the use of SS modes on the HF bands you could also persuade them to allow you greater freedom over where to actually operate? Julian, G4ILO
RE: [digitalradio] Re: Random data vs Spread Spectrum
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 Lester B Veenstra MØYCM K1YCM mailto:les...@veenstras.com les...@veenstras.com mailto:m0...@veenstras.com m0...@veenstras.com mailto:k1...@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 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
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 mailto:digitalradio%40yahoogroups.com, J. Moen j...@... 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
[digitalradio] Re: Random data vs Spread Spectrum
I agree. Which is why people using ROS with a program that supported no other mode (nor RSID) caused such a conflict with people running other software that supported anything but ROS. Julian, G4ILO --- In digitalradio@yahoogroups.com, KH6TY kh...@... wrote: 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
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 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 promise in the way the ARRL/FCC
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 -Original Message- From: Alan Barrow ml9...@pinztrek.com 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 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
Re: [digitalradio] Re: Random data vs Spread Spectrum
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 ml9...@pinztrek.com 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 well be the result of a defined randomizer process followed by multiple layers
Re: [digitalradio] Re: Random data vs Spread Spectrum
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
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
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
[digitalradio] Re: Random data vs Spread Spectrum
Hello Alan, Thank you much for your reply. To tell the truth, I did not subscribe to this group in those beginning days ( posted only om ROSMODEM ) It is so sad, that because of the noise, anti ROS biases, agenda's intelligent exchanges are just about impossible, pro and con. ( IMHO ) Every tine I think to understand why ROS is illegal a couple of days later, I am getting confused. -Bandwidth. -The real properties of FHSS -Is WSJT FHSS? Why , why not. -Why is WSJT65C legal ( just a rhetorical question ) -Is wide band Oliv1a FHSS Why, why not. -Being in public domain. -Specs published. -FCC and others able to monitor content. -ROS transmitted signals not the same from one transmission to another for same message -ROS transmitting while idling -Oversold by am young(?) software engineer not being familiar with US rules. Just to name a few. It is of course because of my limited intelligence, that is clear 73 Rein W6SZ 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
Very simple change just add ³greater than 3 khz² to the existing rules. On 7/13/10 3:28 PM, Dave Wright hfradio...@gmail.com 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 http://www.k3dcw.net
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 j...@jwmoen.com 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
[digitalradio] Re: Random data vs Spread Spectrum
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...@... 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 ml9...@... 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 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
[digitalradio] Re: Random data vs Spread Spectrum
--- In digitalradio@yahoogroups.com, Alan Barrow ml9...@... 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
So 10 times is not a property of SS. Yes 73 Rein W6SZ -Original Message- From: W2XJ w...@w2xj.net 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 j...@jwmoen.com 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
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 ml9...@... 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
Very well stated, separate questions. 73 Rein W6SZ -Original Message- From: J. Moen j...@jwmoen.com 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 ml9...@... 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
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
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
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 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
Re: [digitalradio] Re: Random data vs Spread Spectrum
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
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 CDMA approach on our
[digitalradio] Re: Random data vs Spread Spectrum
Hi Skip. Hope you read it this time: Both these QSO's were on JT. On 18 April we had a long test with VK7MO on 23 cm. We tested a new digital mode called ROS on EME that has seen some use on 144 EME. We saw one good decode from Rex in ROS. We ran out of time and did not complete a QSO in ROS, but it should have been possible. Rex has written a fine article for DUBUS magazine about his findings with ROS. It seems ROS has no real advantages over JT65. We continued on JT65c, while Rex was using his software to eliminate the frequency change due to Doppler shift. This worked very well and we could easily copy him down to 0.5 W. After the Moon window with Rex closed, we worked VK2JDS and VK4CDI with 1 W on JT65. On the same day we managed to do what we believe is the first EME SSTV QSO on 70 cm with HB9Q! Pictures lo from 432 and Above EME Newsletter Aug 2010 http://www.nitehawk.com/rasmit/em70cm.html See under PI9CAS See also last Issue DUBUS Magazine , full report by Rex VK7MO as referenced here before. 73 Rein W6SZ --- In digitalradio@yahoogroups.com, KH6TY kh...@... 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 that, the end user can have some confidence in what he is using, and the state of the art can be mutually advanced. We started with this philosophy with the TTL MAINLINER-II, and continue it today with many of the DSPR systems out there, including the primary commercial company. Their disclosure does not seem to have slowed them down at all. Thanks 73 Les
[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 kh...@... 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 kh...@... kh...@... 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 that, the end user can have some confidence in what he is using, and the state of the art can be mutually advanced. We started with this philosophy with the TTL MAINLINER-II, and continue it today with many of the DSPR systems out there, including the primary commercial company. Their disclosure does not seem to have slowed them down at all. Thanks 73 Les
[digitalradio] Re: Random data vs Spread Spectrum
Just reached this :- 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. And is that not exactly what Jose posted as his first descriptiopn ...a randomized frequency allocation to enable noise cancellation ? As I posted before , this is the only way ahead , to challange the situation , with a way out for all .. this is the third angle .. G .. --- In digitalradio@yahoogroups.com, Lester Veenstra les...@... wrote: Spread spectrum is where, functionally equivalent to the to the randomizer, a pseudo random, or even truly random bits are added at a higher rate than the information bits. In a typical randomizer one bit is produced for each bit in. In the case of spreading, usually a significant number of âextraâ bits are inserted at this point. These bits are not predicted by the input data. Instead, they are random in the sense they are nor correlated to the user data. These extra spreading bits serve to reduce the probability that the transmit energy (its power spectral density) will be observed at any given time in any given bandwidth. These extra bits serve only to reduce the power spectral density over a bandwidth (narrow with respect to the transmit spectral density) but otherwise do not increase the efficiency of the end to end circuit (with one exception I will address shortly). By efficiency, I mean the amount of energy required to get one bit of the input information, prior to any coding, modulation etc., to the users output on the receiver with a particular error rate. (Typically characterized by a performance curve of Eb/No vs B.E.R.) The critical point is, with an end to end link of some particular source coding FEC coding and modulation, its end to end performance can be characterized. in a perfect word, if you then âspread that systemâ by adding extra bits unrelated to the input information, and at receiving side, you knew how to despread, or remove the spreading bits, the link will have the same end to end performance. That is, adding a spread spectrum system around a communications link does not make it work better, and in most real world will actually degrade the end to end performance. This is because the processes used to despread are never perfect. So in a spread system, you have a transmit signal that covers a wider spectrum than the original link, but because the same energy is used, the power spectral density, the amount of energy per unit bandwidth, is reduced. This reduced density has some advantages if you are trying to hide the fact that you are communicating by making your transmit spectral power less than the noise level. Of course if the fellow you are trying to hide from can get close to your transmitter, you pop up from under the noise, and game over. Two other reasons to use spread spectrum, one very real (but not for typical hams) and one a bit illusionary. The reason for most of the spread spectrum in real use is called CDMA, Code Division Multiple Access. Most hams use FDMA, frequency Division Multiple access. For an FDMA example, a great many of us access the 20m band at once, but the multiple accesses to the band are done by each user being on his own frequency (Frequency Division). Of course in this case the stronger user on a given frequency and given path effectively has the access to the channel. In CDMA each user uses the full band, at the same âcarrierâ frequency, but each transmitter has a spreading code that is unique. At the receiver, the desired link is âtunedâ by dispreading with the same extra bit sequence as was used at the transmitter to spread. Signals in the bandwidth having different codes will appear to the despread process as random noise, once the wide band signal desired is despread to a narrow band link. On the receive end of a spread link, the rejection of other spreading codes is also applied to any other signal. The dispreading process will spread the energy of an interfering signal over the spread bandwidth. An example: Assume a unspread link of an occupied bandwidth of 10 kHz and a power of 10 watts. This will have a power spectral density of 10 watts per 10 kHz, or 1 watt per kHz, or 1 mw per Hz. Assume this is spread with a 1 Mchip/s digital signal using
[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
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 kh...@... 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 kh...@... kh...@... 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 that, the end user can have some confidence in what he is using, and the state of the art can be mutually advanced. We started
RE: [digitalradio] Re: Random data vs Spread Spectrum
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 sf...@arrl.org 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 kh...@... 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 kh...@... kh...@... 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
RE: [digitalradio] Re: Random data vs Spread Spectrum
Well I started out life as a Physicist, but had to specialize to find real work HI Lester B Veenstra MØYCM K1YCM mailto:les...@veenstras.com les...@veenstras.com mailto:m0...@veenstras.com m0...@veenstras.com mailto:k1...@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
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 mailto:les...@veenstras.com les...@veenstras.com mailto:m0...@veenstras.com m0...@veenstras.com mailto:k1...@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
