[digitalradio] Re: ARRL/FCC Announcement about ROS
Hi Julian, > By channel coherence time do you mean time when the signal is readable? > The channel choerence time is a property of a (fading) channel which gives an idea of the time interval over with the channel response is approximately *constant*. If you drive your car at 100 km/h and tune your car radio to a far and weak station in the 88/108 MHz FM broadcasting band you have probably noted that the station fades out quite fastly, say with an average rate of 10 Hz, you therefore might expect that the channel response is approximately constant for no more than a small fraction of 1/10Hz = 100 ms. This occurs because the signal you are receiving is the sum of (usually many) different scattered components, each of them coming from a random direction which is not necessary the direction you are driving through. Some of this components could come exactely from the direction you are driving through and are affected by a positive Doppler shift. Some other components could come from the direction you are coming from and they are affected by a negative Doppler shift. Other components could come from directions which form a right angle with yours and the would exhibit no doppler effect. The sum of all of these components can be treated by a stochastic ideal model which is called the (flat) Rayleigh channel model. This (ideal) channel model is essentially characterized by two parameters: 1) the maximum Doppler frequency shift (which is called the "channel Doppler spread") and 2) the average channel attenuation. The Doppler spread (Fd) depends upon a velocity v (the velocity of your car) and the signal carrier frequency Fc through the formula Fd = v/c*Fc (c = light speed). If you do the calculation with v = 27.8 m/s (100 km/h) and Fc = 100 MHz you will find that the Doppler spread is approximately 10 Hz (9.3 Hz, for the sake of precision). Interestingly, the autocorrelation function R(T) (how much two samples of the process are correlated given the time interval T they are separated by) of the flat Raileigh channel model it's quite easy to compute: it's the Bessel function Jo(k*T*Fd) (k is a constant, I don't remember its value, maybe PI or something like that). For T*Fd << 1, the autocorrelation function is not different from unity and this tell us that in a time interval T << 1/Fd the channel response is strongly correlated. This means that if the channel response assumed a value X at time t, the probability that its amplitude does not differ so much from X at time t+T is large. > I can see how this would work using widely separated frequencies. However we > have all observed that when a signal goes down in QSB, it does down right > across the passband. This is not always true and has to do with another parameter which is called the coherence bandwidth of the channel and which is inversely proportional to the "channel time spread". In the HFs it's not unfrequent that the channel time spread is some milliseconds and that the channel coherence bandwith is few hundreds Hertz. Multiple reflections from the F and E ionosphere layers are an example in which this happens. >So do you actually gain anything by spreading the transmission by only 2.2kHz, >other than the ability to annoy people who consider it a selfish waste of >bandwidth? Not always, sure, but you could figure out by yourself the amplitude of public crucifixions if some amateur transmission were designed to be spreaded by 10 kHz or more just because a 2.2 kHz spread is not sufficient to exploit frequency diversity as the ionosphere characteristics would require :-) In any case it is more easy to design a new communication system which copes with a given ionosphere rather than to alter the ionosphere itself. For now we just managed to alter the atmosphere with massive CO2 emissions (and it took one hundred years). For the ionosphere we need more time... 73s Nico, IV3NWV
RE: [digitalradio] Re: ARRL/FCC Announcement about ROS
Nico, I agree 100%. What's needed more than anything is the ability to determine whether a frequency is in use, then we can hop around as much as we want as the MUF changes. As for the FCC - let's just be happy that they only legislate for the US & possessions (colonies) :) Simon Brown, HB9DRV http://sdr-radio.com > -Original Message- > From: digitalradio@yahoogroups.com > > By the way, we amateur radios already experiment daily frequency > hopping spread spectrum communications. > We continuously hop from the 160 m band to the 10 m band accordingly to > the HF propagation conditions and, sincerely, I do not understand why > FCC is so permissive with us (or better, with US amateurs). >
[digitalradio] Re: ARRL/FCC Announcement about ROS
Could I ask you to explain this in terms a ham would understand? --- In digitalradio@yahoogroups.com, "iv3nwv" wrote: > > In a message oriented and power limited fading communication system what > counts is the relationship between the channel coherence time (the time > interval over which the channel response can be considered almost constant) > and the message duration. By channel coherence time do you mean time when the signal is readable? > If the message duration is not much longer than the channel coherence time > there's no other possibility than to exploit frequency diversity. I can see how this would work using widely separated frequencies. However we have all observed that when a signal goes down in QSB, it does down right across the passband. So do you actually gain anything by spreading the transmission by only 2.2kHz, other than the ability to annoy people who consider it a selfish waste of bandwidth? Julian, G4ILO
[digitalradio] Re: ARRL/FCC Announcement about ROS
Hi Jose. > You have a point too nobody had made me to stop and think about. FEC or > UWB in whatever way, carried to the extremes, are two sides of the same > coin. It happens, never mind. Sometimes also telecommunication engineers have not a clear vision of what they are designing :-D > On crowded spectrum, efficiency certainly counts. In a message oriented and power limited fading communication system what counts is the relationship between the channel coherence time (the time interval over which the channel response can be considered almost constant) and the message duration. If the message duration is not much longer than the channel coherence time there's no other possibility than to exploit frequency diversity. In this case, transmitting your message over a narrow band channel whose coherence time were much longer than your message, you would suffer a severe message loss due to the fact that the channel attenuation is frequently larger than the average for the entire duration of your message. If instead the duration of the message were much longer than the channel coherence time, the energy of any message you would receive would be not very different from its average. In this case a clever coding system would not behave so differently from a non fading channel and would approach its capacity by few dBs. For a low-rate system which transmits messages in the range of 50 bits/message and the message length is 60 seconds or so, as i.e. both K1JT's JT65 or WSPR do, there's no need for bandwidth expansion (besides FEC of course). In these cases the channel coherence time is usually much less than the message duration and frequency diversity would be of little help. Joe designed them well :-) For communication systems with the same message information content but in which messages were required to be transmitted much faster, say in three seconds, the channel coherence time would be of the same order of magnitude of the message length and time diversity can't be exploited. In this cases, frequency diversity is mandatory whether implemented by what FCC calls a "spread spectrum" system or not. This is what, in my opinion, ROS has tried to address. I couldn't care less if it is legal or not, I just hope it could cohexist with the modes I'm already using. Mr. Darwin selection rules will do their job and select the better. By the way, we amateur radios already experiment daily frequency hopping spread spectrum communications. We continuously hop from the 160 m band to the 10 m band accordingly to the HF propagation conditions and, sincerely, I do not understand why FCC is so permissive with us (or better, with US amateurs). Has this to do with federal agents reaction times? ;-) 73s, Nico, IV3NWV
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
El 06/03/2010 19:44, iv3nwv escribió: > Jose, > if you are referring to me I'm not saying that theoretically it is correct to > use as much bandwidth as possible. This is a conclusion you have drawn on > your own. > > Using a 100 kHz bandwith to communicate information at a rate of 1 bit/s > could by sure approach any channel capacity, but the spectral efficiency of > such a communication channel would be quite questionable. Let this option to > NASA deep space communications. > What we need are modes which are both power AND bandwidth efficient. > > I think that the term "spread spectrum" here is misleading. > What's the difference between a communication system which uses a FEC code > with a very low rate, say R=0.01 (one information bit per one hundreds > symbols), and a communication system which hops or spreads the modulating > signal on an equivalent bandwidth? > In my opinion: NONE. > Both systems are using a bandwidth which is one hundreds time the bandwidth > which would be used by an uncoded system. > > The problem is not whether a system is spread spectrum or not. > The problem is how much it is bandwidth efficient. > > Everyone knows that an ortoghonal signalling system approaches the (AWGN) > channel capacity. The legitimate question is if the whole 20 m band should be > used to achieve such a result to communicate information at 3 bit/s. > > For what I know ROS has a really poor bandwidth efficience nor it copes with > MUI (multiuser interference) issues. > I do not doubt that it can achieve an exciting performance under the power > efficiency point of view, but that's not all. > We are called to develop systems which are efficient also in respect to > bandwidth. > > The spread spectrum story is just a bad motivation used against true concerns. > > 73s > Nico, IV3NWV Nico, Excuse me if I misunderstood it. I believe it is theoretically correct, but not always practical nor possible. For one, I agree that it is incorrect to run over a whole crowded band like 20 meters. You have a point too nobody had made me to stop and think about. FEC or UWB in whatever way, carried to the extremes, are two sides of the same coin. On crowded spectrum, efficiency certainly counts. Nevertheless, it is a complex issue, because I also believe that unprotected systems, like packet has traditionally been is also a waste of bandwidth when a single lost bit sends, say, 255 bytes to trash. As usual, the solution may hardly be on the extremes. 73, Jose, CO2JA
[digitalradio] Re: ARRL/FCC Announcement about ROS
Jose, if you are referring to me I'm not saying that theoretically it is correct to use as much bandwidth as possible. This is a conclusion you have drawn on your own. Using a 100 kHz bandwith to communicate information at a rate of 1 bit/s could by sure approach any channel capacity, but the spectral efficiency of such a communication channel would be quite questionable. Let this option to NASA deep space communications. What we need are modes which are both power AND bandwidth efficient. I think that the term "spread spectrum" here is misleading. What's the difference between a communication system which uses a FEC code with a very low rate, say R=0.01 (one information bit per one hundreds symbols), and a communication system which hops or spreads the modulating signal on an equivalent bandwidth? In my opinion: NONE. Both systems are using a bandwidth which is one hundreds time the bandwidth which would be used by an uncoded system. The problem is not whether a system is spread spectrum or not. The problem is how much it is bandwidth efficient. Everyone knows that an ortoghonal signalling system approaches the (AWGN) channel capacity. The legitimate question is if the whole 20 m band should be used to achieve such a result to communicate information at 3 bit/s. For what I know ROS has a really poor bandwidth efficience nor it copes with MUI (multiuser interference) issues. I do not doubt that it can achieve an exciting performance under the power efficiency point of view, but that's not all. We are called to develop systems which are efficient also in respect to bandwidth. The spread spectrum story is just a bad motivation used against true concerns. 73s Nico, IV3NWV --- In digitalradio@yahoogroups.com, "Jose A. Amador" wrote: > > > I agree with Nino, theoretically it is correct to use as much bandwidth > as possible, 3 kHz in the ROS case, but due to the small spreading, the > ROS signal does not have a "negligble level" compared to others on the > channel, so it is a halfbreed, it has spread spectrum characteristics, > but does not quite behave like the "pure" definition. > > ROS still had problems in version 1.6.3 and it is easy to notice that it > works in a free channel, but does not stand burst errors (in fact, > errors long as a packet or pactor frame length) and its ability to copy > crumbles. That does not happen, at least so noticeably, with JT65 or Olivia. > > 73, > > Jose, CO2JA > >
RE: [digitalradio] Re: ARRL/FCC Announcement about ROS
Hello Dave, ( AA6YQ ) I see your point with the use on HF Thanks for your thoughtful reply. 73 Rein W6SZ -Original Message- >From: Dave AA6YQ >Sent: Mar 6, 2010 7:03 AM >To: digitalradio@yahoogroups.com >Subject: RE: [digitalradio] Re: ARRL/FCC Announcement about ROS > >>>>AA6YQ comments below > > > >From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On >Behalf Of rein...@ix.netcom.com >Sent: Saturday, March 06, 2010 5:50 AM >To: digitalradio@yahoogroups.com >Subject: RE: [digitalradio] Re: ARRL/FCC Announcement about ROS > > > > > > >Hi Dave, ( AA6YQ ) > >Thanks. I might just do that next Monday. > >I understand it to be, some help/emergency phone line? > >>>>It’s not an emergency phone line. I >Lost the number, so if you have it, please send it to me. > >>>>call (877) 480-3201, choose option #2, and when a person answers ask for >>>>“Dawn” (agent 3820). > > >I am also very much interested in your definition of ss. > > >I have not been able to find anything, Wikipedia really >does not count in this case. > >>>>I don’t have a definition, Rein; I agree with you that the Wikipedia entry >>>>is not authoritative. The fact that part 97 references spread spectrum >>>>without defining it is one of the root causes of this controversy, leaving >>>>us to make “individual decisions” in the absence of decision criteria. >>>>Transparency (ability for anyone to copy without a private key) and >>>>spreading factor are clearly important factors, but to what does the >>>>spreading factor apply? Information content? Bandwidth of the signal being >>>>spread? Mike N4QLB claims in a post on the ROS reflector that “it’s not >>>>spread spectrum if the resulting bandwidth is 3 khz”. Is that true? If so, >>>>why 3 khz, as opposed to, say, 3.1 khz? > >>>>While the assessment of a digital mode’s legality in the US is left to the >>>>operator, the decision to impose a penalty in an operator for using an >>>>illegal mode lies with the FCC. Given the FCC’s declaration that “ROS is >>>>viewed as spread spectrum” and the ARRL’s similar public announcement, I >>>>would be hard-pressed to explain why my use of ROS should not result in a >>>>serious fine or loss of license. Thus I am not using ROS on HF bands. > >>>>Said another way, US amateurs can decide to use ROS, but they’d best have a >>>>killer technical argument for its legality at the ready. > >73, > > Dave, AA6YQ >
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
Hello Jose, Thank you for addressing my questions. I am not going to order that book, even I could find a copy. And I do not live close enough to libraries carrying it. We need a "SS for Dummies". In any case, thank you for addressing the question. Kind Regards, Rein W6SZ -Original Message- >From: "Jose A. Amador" >Sent: Mar 6, 2010 6:37 AM >To: Rein A >Cc: digitalradio >Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS > >El 06/03/2010 4:49, rein...@ix.netcom.com escribió: >> I thought, that there has to be a direct specific connection >> between the transmitter and the receiver on how to retrieve >> the "info" from the spread spectrum. ( SS for dummies ) >> >> This makes it useful for the militairy, for who it was >> originally designed and in the case of cell phones, for >> instance, the code recovery algorithm is programmmed in >> the system, not secret, I assume, but still hard to figure. >> I thought cell phones run over 1,5 Mhz wide spreading. >> >> Is this true? I for one have never thought or learned >> much about SS. ( 75 yrs and retired and I am sure some >> will say you know what ) >> >> 3000 Hz info band -> 1.5 10 e+6,Hz ? >> >> Anyway what is so frustrating to me here, is that I do not >> see a straight definition of SS written in a published book >> that I can cross reference. >> > >Carlson, Bruce, Communications Systems, Chapter 15 Spread Spectrum >Systems, p 671, Mc Graw Hill 2002 > >> I have the ARRL SS source book, and there, all I can find is >> that SS spreads the "info band" width between 10 and 100 times. >> >> Also I thought if one looks with a Spectrum Analyzer,( I have >> never done that, ) to a SS signal, is is hard to see the side bands. >> Signals so weak and so random, perhaps semi- that one can >> have a large number of those side bands from different transmitters >> overlapping without causing problems in the communication >> process. >> > >It should be that way. But ROS has insignificant spreading when compared >to what has become publicly known about SS (i.e., 802.11). > >> Just a INCREASED noise level, that would seriously be a problem >> for EME, for instance, it would cover up the natural background >> or with other words, increase the noise temperature, >> >> Now here you have a few simple concepts, it is crazy talk >> yes or no? Please feel free to tell your views with a >> basis, where I can look it up myself. >> I asked before for a peer reviewed paper "SS for laypersons >> or dummies" >> >> I do only WSJT on HF and on EME as group member, please someone explain >> to me why WSJT is, what? >JT65A is MFSK with a heavy block coding scheme and high redundancy. It >is NOT spread spectrum. > >> It appears to be legal? >> > >Yes, it is NOT SS and occupies some 170 Hz. It is WELL DOCUMENTED by Dr. >Joseph Taylor, K1JT, a Nobel Prize Laureate and Princeton Professor. > >> What is the difference between JT65C and ROS when it relates >> to the SPREAD Spectrum properties, >> > >Apples and oranges. ROS does not quite reach the level of >sophistication of WSJT, within the bounds allowed to hams in the US. > >> WSJT has a smart and efficient info packing scheme that makes >> it pretty much an all or nothing system. ROS, produces >> a lot of errors, if the signal strenght goes down after >> the start, but that is not a SS issue, >> >Certainly not. ROS is a baby compared to JT65 robustness. >> Please explain to me and perhaps quite a few others what >> SS is, other than that is "Wide" Im my own mind the width >> has not really too much to do with it? True or false. >> >Ideally, SS should be of infinite bandwidth, which is not viable in >practice. As you reduce it to a practical, allowable level, its "magic >properties" >lose strenght, be it direct sequence or frequency hopping. >Theoretically, FH should have a very small dwell time, but then again, >to contain at least 90% of the spread message sidebands in a 3 kHz >bandwidth makes it "not undescernible from noise". >> All straight layman's questions, so who answers them, most of us >> like to learn and understand a little. >> >> 73 Rein W6SZ >> > >73, > >Jose, CO2JA > > > > > > > >Try Hamspots, PSKreporter, and K3UK Sked Page >http://www.obriensweb.com/skedpskr4.html >Suggesting calling frequencies: Modes <500Hz 3583,7073,14073,18103, >21073,24923, 28123 . Wider modes e.g. Olivia 32/1000, ROS16, ALE: 14109.7088. >Yahoo! Groups Links > > >
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
El 06/03/2010 10:03, Dave AA6YQ escribió: >>>I don’t have a definition, Rein; I agree with you that the Wikipedia entry is not authoritative. The fact that part 97 references spread spectrum without defining it is one of the root causes of this controversy, leaving us to make “individual decisions” in the absence of decision criteria. Transparency (ability for anyone to copy without a private key) and spreading factor are clearly important factors, but to what does the spreading factor apply? Information content? Bandwidth of the signal being spread? Mike N4QLB claims in a post on the ROS reflector that “it’s not spread spectrum if the resulting bandwidth is 3 khz”. Is that true? If so, why 3 khz, as opposed to, say, 3.1 khz? Bandwidth of the RESULTING signal. Depends mostly on the chipping frequency and waveform (DSSS) or spread of center frequencies and dwell time (FHSS) independent of the message. Ideally, it should not be discernible from noise, but the FHSS scheme ROS uses does not reduce spectral power density to such low levels in a 3 kHz bandwidth. The chipping should be many times faster than the baseband bandwidth, with no specific, fixed figure. All real systems have finite bandwidth to be realizable, and ROS is no exception. The fact that the bandwidth is that of a SSB voice channel is imposed by the available hardware (radios). The QRM potential does not come from the bandwidth alone, but also from the resultant spectral power density achieved in such a bandwidth. No SS system can achieve the ideal limits due to hardware and administrative constraints, even 802.11 systems. What is at a stake is also the blurred, fuzzy limits that real systems have nowadays in practice. I do believe that there should be room for such systems, as much as there is room for Olivia wide modes or MT63, and there are specific frequencies for such modes. So far, even using a different paradigm, ROS does not achieve such a robustness in practice, because of what it still lacks. But that is something else, as is the possible presence of backdoors. I do recommend a personal firewall, I am using an old one by Kerio, that fields and denies all non acceptable background communications, even when I do not have a direct connection to the Internet, as it "rings the bell" whenever such an unauthorized attempt happens. Not only that, it has rules to effectively deny any further attempts. Nothing is 100% safe, but it does less harm that way. Anyone can check the spectrum of the baseband signal using the proper tool. I used Spectran and a loopback cable for simplicity on my PC. Others have used Spectrum Lab, believe even Visual Analyzer could help as well. 73, Jose, CO2JA
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
I agree with Nino, theoretically it is correct to use as much bandwidth as possible, 3 kHz in the ROS case, but due to the small spreading, the ROS signal does not have a "negligble level" compared to others on the channel, so it is a halfbreed, it has spread spectrum characteristics, but does not quite behave like the "pure" definition. ROS still had problems in version 1.6.3 and it is easy to notice that it works in a free channel, but does not stand burst errors (in fact, errors long as a packet or pactor frame length) and its ability to copy crumbles. That does not happen, at least so noticeably, with JT65 or Olivia. 73, Jose, CO2JA El 05/03/2010 20:22, iv3nwv escribió: > Julian, > thanks for your comments. > > Yes, laws are laws. > Also the Hammurabi rule "If a man puts out the eye of an equal, his eye shall > be put out" was a law but I don't think that it would be of great help in our > modern society. > > I agree with you that simulations should be performed prior to any other "on > air" experiment. I think that this is already a common practice nowadays or > at least that nobody interested in a serious development would omit to > perform it today. > > I also agree that amateur bands are not just an experimenter's playground but > this implicitly means that they are not exclusive to "communicators". > If I were an experimenter I would like to see acknowledged my right to make > my experiments somewhere in our bands. I would have no interest interfering > other users activity, I would just need a portion of the spectrum where me or > other amateurs on the other side of the Atlantic Ocean were not considered > criminals just because we are validating a model on the field. > > I don't agree that we should use modes which have already been invented and > stop looking for new ones. Research and development in communications and in > information theory are everything but dead. > Turbo codes were submitted to the attention of the research community just > fiftheen years ago, when many had already missed the hope that the Shannon > channel capacity could be really approached. > Should Berrou, Glavieux and Thitimajshima have made more use of what had been > already invented instead of experimenting what had not be done yet? And what > about those who dedicated their time inventing new efficient algorithms to > decode LDPC (or Gallager's) codes, as David MacKay did few years later? > Koetter (unfortunately passed away at a still young age), one of the two > researchers who found an algebraic soft decision method to decode better than > before the Reed-Solomon codes, as those used in Joe's JT65, published his > work in 2003 or so. > Should we have stopped our alternatives to knowledge and technologies > available in 2002? I don't think so. > We should better keep up with news and new modes. > > Nico, IV3NWV
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
El 06/03/2010 4:49, rein...@ix.netcom.com escribió: > I thought, that there has to be a direct specific connection > between the transmitter and the receiver on how to retrieve > the "info" from the spread spectrum. ( SS for dummies ) > > This makes it useful for the militairy, for who it was > originally designed and in the case of cell phones, for > instance, the code recovery algorithm is programmmed in > the system, not secret, I assume, but still hard to figure. > I thought cell phones run over 1,5 Mhz wide spreading. > > Is this true? I for one have never thought or learned > much about SS. ( 75 yrs and retired and I am sure some > will say you know what ) > > 3000 Hz info band -> 1.5 10 e+6,Hz ? > > Anyway what is so frustrating to me here, is that I do not > see a straight definition of SS written in a published book > that I can cross reference. > Carlson, Bruce, Communications Systems, Chapter 15 Spread Spectrum Systems, p 671, Mc Graw Hill 2002 > I have the ARRL SS source book, and there, all I can find is > that SS spreads the "info band" width between 10 and 100 times. > > Also I thought if one looks with a Spectrum Analyzer,( I have > never done that, ) to a SS signal, is is hard to see the side bands. > Signals so weak and so random, perhaps semi- that one can > have a large number of those side bands from different transmitters > overlapping without causing problems in the communication > process. > It should be that way. But ROS has insignificant spreading when compared to what has become publicly known about SS (i.e., 802.11). > Just a INCREASED noise level, that would seriously be a problem > for EME, for instance, it would cover up the natural background > or with other words, increase the noise temperature, > > Now here you have a few simple concepts, it is crazy talk > yes or no? Please feel free to tell your views with a > basis, where I can look it up myself. > I asked before for a peer reviewed paper "SS for laypersons > or dummies" > > I do only WSJT on HF and on EME as group member, please someone explain > to me why WSJT is, what? JT65A is MFSK with a heavy block coding scheme and high redundancy. It is NOT spread spectrum. > It appears to be legal? > Yes, it is NOT SS and occupies some 170 Hz. It is WELL DOCUMENTED by Dr. Joseph Taylor, K1JT, a Nobel Prize Laureate and Princeton Professor. > What is the difference between JT65C and ROS when it relates > to the SPREAD Spectrum properties, > Apples and oranges. ROS does not quite reach the level of sophistication of WSJT, within the bounds allowed to hams in the US. > WSJT has a smart and efficient info packing scheme that makes > it pretty much an all or nothing system. ROS, produces > a lot of errors, if the signal strenght goes down after > the start, but that is not a SS issue, > Certainly not. ROS is a baby compared to JT65 robustness. > Please explain to me and perhaps quite a few others what > SS is, other than that is "Wide" Im my own mind the width > has not really too much to do with it? True or false. > Ideally, SS should be of infinite bandwidth, which is not viable in practice. As you reduce it to a practical, allowable level, its "magic properties" lose strenght, be it direct sequence or frequency hopping. Theoretically, FH should have a very small dwell time, but then again, to contain at least 90% of the spread message sidebands in a 3 kHz bandwidth makes it "not undescernible from noise". > All straight layman's questions, so who answers them, most of us > like to learn and understand a little. > > 73 Rein W6SZ > 73, Jose, CO2JA
RE: [digitalradio] Re: ARRL/FCC Announcement about ROS
>>>AA6YQ comments below From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On Behalf Of rein...@ix.netcom.com Sent: Saturday, March 06, 2010 5:50 AM To: digitalradio@yahoogroups.com Subject: RE: [digitalradio] Re: ARRL/FCC Announcement about ROS Hi Dave, ( AA6YQ ) Thanks. I might just do that next Monday. I understand it to be, some help/emergency phone line? >>>It’s not an emergency phone line. I Lost the number, so if you have it, please send it to me. >>>call (877) 480-3201, choose option #2, and when a person answers ask for >>>“Dawn” (agent 3820). I am also very much interested in your definition of ss. I have not been able to find anything, Wikipedia really does not count in this case. >>>I don’t have a definition, Rein; I agree with you that the Wikipedia entry >>>is not authoritative. The fact that part 97 references spread spectrum >>>without defining it is one of the root causes of this controversy, leaving >>>us to make “individual decisions” in the absence of decision criteria. >>>Transparency (ability for anyone to copy without a private key) and >>>spreading factor are clearly important factors, but to what does the >>>spreading factor apply? Information content? Bandwidth of the signal being >>>spread? Mike N4QLB claims in a post on the ROS reflector that “it’s not >>>spread spectrum if the resulting bandwidth is 3 khz”. Is that true? If so, >>>why 3 khz, as opposed to, say, 3.1 khz? >>>While the assessment of a digital mode’s legality in the US is left to the >>>operator, the decision to impose a penalty in an operator for using an >>>illegal mode lies with the FCC. Given the FCC’s declaration that “ROS is >>>viewed as spread spectrum” and the ARRL’s similar public announcement, I >>>would be hard-pressed to explain why my use of ROS should not result in a >>>serious fine or loss of license. Thus I am not using ROS on HF bands. >>>Said another way, US amateurs can decide to use ROS, but they’d best have a >>>killer technical argument for its legality at the ready. 73, Dave, AA6YQ
[digitalradio] Re: ARRL/FCC Announcement about ROS
--- In digitalradio@yahoogroups.com, "iv3nwv" wrote: > > I also agree that amateur bands are not just an experimenter's playground but > this implicitly means that they are not exclusive to "communicators". > If I were an experimenter I would like to see acknowledged my right to make > my experiments somewhere in our bands. I would have no interest interfering > other users activity, I would just need a portion of the spectrum where me or > other amateurs on the other side of the Atlantic Ocean were not considered > criminals just because we are validating a model on the field. I agree with this, and in a letter I wrote to the RSGB RadCom (and copied to G4JNT the RadCom data modes columnist) I suggested that a portion of each band should be set aside for just such experimentation. One question, of course, is whether releasing the software for a new mode to all and sundry just so that they can fill their logs with local contacts using it counts as experimentation. It is not the ROS mode itself that is the problem, so much as the people who are using it. > > I don't agree that we should use modes which have already been invented and > stop looking for new ones. Research and development in communications and in > information theory are everything but dead. > Turbo codes were submitted to the attention of the research community just > fiftheen years ago, when many had already missed the hope that the Shannon > channel capacity could be really approached. > Should Berrou, Glavieux and Thitimajshima have made more use of what had been > already invented instead of experimenting what had not be done yet? And what > about those who dedicated their time inventing new efficient algorithms to > decode LDPC (or Gallager's) codes, as David MacKay did few years later? > Koetter (unfortunately passed away at a still young age), one of the two > researchers who found an algebraic soft decision method to decode better than > before the Reed-Solomon codes, as those used in Joe's JT65, published his > work in 2003 or so. > Should we have stopped our alternatives to knowledge and technologies > available in 2002? I don't think so. > We should better keep up with news and new modes. > I agree. However I hope you would also agree that there is insufficient spectrum space to allow uncontrolled use of an infinite number of different modes. The argument that a frequency can be yours if no-one else is using it is all very well, but it cannot be practically implemented with modes that cannot communicate with one another to determine whether it is in use or not. To give a very real example of the moment, the Olivia mode uses specific frequencies or channels because it is a weak signal mode and it is possible to communicate with signals that can neither be heard nor seen on the waterfall. Olivia users tune their receivers to precise frequencies in order to listen for weak signals that they would not detect on the band at random. But ROS users are now being advised to use the same frequencies that Olivia has been using. This is inevitably leading to interference by ROS to Olivia (and quite possibly also by Olivia to ROS since that can also decode weak signals) which is resulting in exchanges that I have seen using some very bad language which does the hobby no credit at all. You will hopefully agree that there is not a limitless amount of space for all modes to have their own exclusive allocations. However I don't know how you can arrange for incompatible modes to share the same frequency without mutual interference. Therefore I would suggest that the only answer is to limit the number of modes that can be used and only allow new ones to go beyond the experimental stage into general use if they turn out to offer some significant benefit over existing ones. (Equally I would agree that you could deprecate the use of modes that have fallen out of favour to make way for newer ones.) Julian, G4ILO
RE: [digitalradio] Re: ARRL/FCC Announcement about ROS
Hi Dave, ( AA6YQ ) Thanks. I might just do that next Monday. I understand it to be, some help/emergency phone line? Lost the number, so if you have it, please send it to me. I am also very much interested in your definition of ss. I have not been able to find anything, Wikipedia really does not count in this case. I thought, that there has to be a direct specific connection between the transmitter and the receiver on how to retrieve the "info" from the spread spectrum. ( SS for dummies ) This makes it useful for the militairy, for who it was originally designed and in the case of cell phones, for instance, the code recovery algorithm is programmmed in the system, not secret, I assume, but still hard to figure. I thought cell phones run over 1,5 Mhz wide spreading. Is this true? I for one have never thought or learned much about SS. ( 75 yrs and retired and I am sure some will say you know what ) 3000 Hz info band -> 1.5 10 e+6,Hz ? Anyway what is so frustrating to me here, is that I do not see a straight definition of SS written in a published book that I can cross reference. I have the ARRL SS source book, and there, all I can find is that SS spreads the "info band" width between 10 and 100 times. Also I thought if one looks with a Spectrum Analyzer,( I have never done that, ) to a SS signal, is is hard to see the side bands. Signals so weak and so random, perhaps semi- that one can have a large number of those side bands from different transmitters overlapping without causing problems in the communication process. Just a INCREASED noise level, that would seriously be a problem for EME, for instance, it would cover up the natural background or with other words, increase the noise temperature, Now here you have a few simple concepts, it is crazy talk yes or no? Please feel free to tell your views with a basis, where I can look it up myself. I asked before for a peer reviewed paper "SS for laypersons or dummies" I do only WSJT on HF and on EME as group member, please someone explain to me why WSJT is, what? It appears to be legal? What is the difference between JT65C and ROS when it relates to the SPREAD Spectrum properties, WSJT has a smart and efficient info packing scheme that makes it pretty much an all or nothing system. ROS, produces a lot of errors, if the signal strenght goes down after the start, but that is not a SS issue, Please explain to me and perhaps quite a few others what SS is, other than that is "Wide" Im my own mind the width has not really too much to do with it? True or false. All straight layman's questions, so who answers them, most of us like to learn and understand a little. 73 Rein W6SZ -Original Message- >From: Dave AA6YQ >Sent: Mar 5, 2010 11:28 PM >To: digitalradio@yahoogroups.com >Subject: RE: [digitalradio] Re: ARRL/FCC Announcement about ROS > >Rein, why don’t you call Dawn (FCC agent 3820) and ask her why the FCC chose >to communicate through the ARRL; the phone number has been posted in previous >messages here, but I’ll dig it back up if needed. > > > >73, > > > >Dave, AA6YQ > > > >From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On >Behalf Of rein...@ix.netcom.com >Sent: Friday, March 05, 2010 12:18 PM >To: digitalradio@yahoogroups.com >Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS > > > > > >Hi Trevor. > >In my opinion, your points are very well taken. > >It appears to me strange, at best, that an US federal branch is >using an hobby club with a membership ratio of some 50 % of >the total US population to communicate via thatclub matters >of law. > >Even with the 50 % membership, the percentage of members >following the day in and out operations is much lower. > >I can imagine perhaps one reason that this has not happened, >a lack of resources at the Federal Communication Commission >though that seems to be unlikely. > >The FCC has very effective ways to communicate with us, if >need be, > >I am a member of the ARRL and have been that for 40 years. > >73 Rein W6SZ > > >-----Original Message- >>From: "Trevor ." mailto:m5aka%40yahoo.co.uk> > >>Sent: Mar 5, 2010 5:13 AM >>To: digitalradio@yahoogroups.com <mailto:digitalradio%40yahoogroups.com> >>Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS >> >>All the ARRL announcement really does is reference the FCC statement of Feb. >>23. >> >>That statement said the FCC was not going to say if it considered ROS to be >>spread spectrum. Individual operators were the ones responsible for making a >>decision. >> >>The FCC has never said ROS is "illegal" nor have the ARRL. >>
[digitalradio] Re: ARRL/FCC Announcement about ROS
The FCC is very slow to respond to anything related amateur radio. In other words we're a very minor player in the scheme of things. I for one will refrain from using ROS below 222Mhz until it is approved because my license is more valuable to me . Everyone is entitled to their own opinion and that my friends in mine..73, Alan --- In digitalradio@yahoogroups.com, "Trevor ." wrote: > > All the ARRL announcement really does is reference the FCC statement of Feb. > 23. > > That statement said the FCC was not going to say if it considered ROS to be > spread spectrum. Individual operators were the ones responsible for making a > decision. > > The FCC has never said ROS is "illegal" nor have the ARRL. > > I've had a trawl through the FCC site but couldn't find a definition there of > what they mean by the words "Spread Spectrum" and it's their definition that > matters not other peoples. > > If the FCC were concerned about the use of ROS on HF you would have thought > they would have written to at least one of the US stations that they had > observed using it and informed them of a breach of regulations. I am not > aware that they have done so. > > 73 Trevor M5AKA >
RE: [digitalradio] Re: ARRL/FCC Announcement about ROS
Rein, why don’t you call Dawn (FCC agent 3820) and ask her why the FCC chose to communicate through the ARRL; the phone number has been posted in previous messages here, but I’ll dig it back up if needed. 73, Dave, AA6YQ From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On Behalf Of rein...@ix.netcom.com Sent: Friday, March 05, 2010 12:18 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS Hi Trevor. In my opinion, your points are very well taken. It appears to me strange, at best, that an US federal branch is using an hobby club with a membership ratio of some 50 % of the total US population to communicate via thatclub matters of law. Even with the 50 % membership, the percentage of members following the day in and out operations is much lower. I can imagine perhaps one reason that this has not happened, a lack of resources at the Federal Communication Commission though that seems to be unlikely. The FCC has very effective ways to communicate with us, if need be, I am a member of the ARRL and have been that for 40 years. 73 Rein W6SZ -Original Message- >From: "Trevor ." mailto:m5aka%40yahoo.co.uk> > >Sent: Mar 5, 2010 5:13 AM >To: digitalradio@yahoogroups.com <mailto:digitalradio%40yahoogroups.com> >Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS > >All the ARRL announcement really does is reference the FCC statement of Feb. >23. > >That statement said the FCC was not going to say if it considered ROS to be >spread spectrum. Individual operators were the ones responsible for making a >decision. > >The FCC has never said ROS is "illegal" nor have the ARRL. > >I've had a trawl through the FCC site but couldn't find a definition there of >what they mean by the words "Spread Spectrum" and it's their definition that >matters not other peoples. > >If the FCC were concerned about the use of ROS on HF you would have thought >they would have written to at least one of the US stations that they had >observed using it and informed them of a breach of regulations. I am not aware >that they have done so. > >73 Trevor M5AKA > > > > > > > > >Try Hamspots, PSKreporter, and K3UK Sked Page >http://www.obriensweb.com/skedpskr4.html >Suggesting calling frequencies: Modes <500Hz 3583,7073,14073,18103, >21073,24923, 28123 . Wider modes e.g. Olivia 32/1000, ROS16, ALE: 14109.7088. >Yahoo! Groups Links > > >
[digitalradio] Re: ARRL/FCC Announcement about ROS
Julian, thanks for your comments. Yes, laws are laws. Also the Hammurabi rule "If a man puts out the eye of an equal, his eye shall be put out" was a law but I don't think that it would be of great help in our modern society. I agree with you that simulations should be performed prior to any other "on air" experiment. I think that this is already a common practice nowadays or at least that nobody interested in a serious development would omit to perform it today. I also agree that amateur bands are not just an experimenter's playground but this implicitly means that they are not exclusive to "communicators". If I were an experimenter I would like to see acknowledged my right to make my experiments somewhere in our bands. I would have no interest interfering other users activity, I would just need a portion of the spectrum where me or other amateurs on the other side of the Atlantic Ocean were not considered criminals just because we are validating a model on the field. I don't agree that we should use modes which have already been invented and stop looking for new ones. Research and development in communications and in information theory are everything but dead. Turbo codes were submitted to the attention of the research community just fiftheen years ago, when many had already missed the hope that the Shannon channel capacity could be really approached. Should Berrou, Glavieux and Thitimajshima have made more use of what had been already invented instead of experimenting what had not be done yet? And what about those who dedicated their time inventing new efficient algorithms to decode LDPC (or Gallager's) codes, as David MacKay did few years later? Koetter (unfortunately passed away at a still young age), one of the two researchers who found an algebraic soft decision method to decode better than before the Reed-Solomon codes, as those used in Joe's JT65, published his work in 2003 or so. Should we have stopped our alternatives to knowledge and technologies available in 2002? I don't think so. We should better keep up with news and new modes. Nico, IV3NWV --- In digitalradio@yahoogroups.com, "g4ilo" wrote: > > Laws are laws, whether you like them or not. And, in this particular context, > is it actually necessary to go on the air to carry out experiments of this > type? As has been mentioned in several posts. there are ionospheric > simulators that permit the testing of different modes. > > The amateur bands are not just an experimenter's playground. They are also > used for communication. And communication becomes increasingly difficult when > you have a Tower of Babel of different, mutually incompatible modes competing > for the same frequencies. > > There are dozens of data modes that have been developed in the last few years > and most now simply lie unused because not enough people were interested in > using them to make it possible to have everyday contacts. Would it not be > better to make more use of the modes we already have than keep on inventing > new ones? > > I think that before any mode is allowed off the simulator and into general > use it should be proven to have benefits not provided by any pre-existing > modes, as well as to justify its use of bandwidth. I think there is an > argument for setting aside a small section of space for on-air > experimentation with unapproved modes. But the situation where existing users > of the bands suddenly have their activities disrupted when people start going > mad with some flavour of the month new mode is unacceptable, and the controls > the FCC exercise over amateurs in the USA do at least go some way to prevent > this. > > Julian, G4ILO
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
Hi Trevor. In my opinion, your points are very well taken. It appears to me strange, at best, that an US federal branch is using an hobby club with a membership ratio of some 50 % of the total US population to communicate via thatclub matters of law. Even with the 50 % membership, the percentage of members following the day in and out operations is much lower. I can imagine perhaps one reason that this has not happened, a lack of resources at the Federal Communication Commission though that seems to be unlikely. The FCC has very effective ways to communicate with us, if need be, I am a member of the ARRL and have been that for 40 years. 73 Rein W6SZ -Original Message- >From: "Trevor ." >Sent: Mar 5, 2010 5:13 AM >To: digitalradio@yahoogroups.com >Subject: Re: [digitalradio] Re: ARRL/FCC Announcement about ROS > >All the ARRL announcement really does is reference the FCC statement of Feb. >23. > >That statement said the FCC was not going to say if it considered ROS to be >spread spectrum. Individual operators were the ones responsible for making a >decision. > >The FCC has never said ROS is "illegal" nor have the ARRL. > >I've had a trawl through the FCC site but couldn't find a definition there of >what they mean by the words "Spread Spectrum" and it's their definition that >matters not other peoples. > >If the FCC were concerned about the use of ROS on HF you would have thought >they would have written to at least one of the US stations that they had >observed using it and informed them of a breach of regulations. I am not aware >that they have done so. > >73 Trevor M5AKA > > > > > > > > >Try Hamspots, PSKreporter, and K3UK Sked Page >http://www.obriensweb.com/skedpskr4.html >Suggesting calling frequencies: Modes <500Hz 3583,7073,14073,18103, >21073,24923, 28123 . Wider modes e.g. Olivia 32/1000, ROS16, ALE: 14109.7088. >Yahoo! Groups Links > > >
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
All the ARRL announcement really does is reference the FCC statement of Feb. 23. That statement said the FCC was not going to say if it considered ROS to be spread spectrum. Individual operators were the ones responsible for making a decision. The FCC has never said ROS is "illegal" nor have the ARRL. I've had a trawl through the FCC site but couldn't find a definition there of what they mean by the words "Spread Spectrum" and it's their definition that matters not other peoples. If the FCC were concerned about the use of ROS on HF you would have thought they would have written to at least one of the US stations that they had observed using it and informed them of a breach of regulations. I am not aware that they have done so. 73 Trevor M5AKA
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
" But the situation where existing users of the bands suddenly have their activities disrupted when people start going mad with some flavour of the month new mode is unacceptable, and the controls the FCC exercise over amateurs in the USA do at least go some way to prevent this. " This is why we fought wide band digital on 6 and 2 meters. The idea that a very small number of hams could disrupt entire bands for the mode of week was unacceptable. One reason spark gap and modulated oscillators are illegal is because they too were wide band in places that had only limited space for all users. You have 223 mhz and above use it.
[digitalradio] Re: ARRL/FCC Announcement about ROS
Laws are laws, whether you like them or not. And, in this particular context, is it actually necessary to go on the air to carry out experiments of this type? As has been mentioned in several posts. there are ionospheric simulators that permit the testing of different modes. The amateur bands are not just an experimenter's playground. They are also used for communication. And communication becomes increasingly difficult when you have a Tower of Babel of different, mutually incompatible modes competing for the same frequencies. There are dozens of data modes that have been developed in the last few years and most now simply lie unused because not enough people were interested in using them to make it possible to have everyday contacts. Would it not be better to make more use of the modes we already have than keep on inventing new ones? I think that before any mode is allowed off the simulator and into general use it should be proven to have benefits not provided by any pre-existing modes, as well as to justify its use of bandwidth. I think there is an argument for setting aside a small section of space for on-air experimentation with unapproved modes. But the situation where existing users of the bands suddenly have their activities disrupted when people start going mad with some flavour of the month new mode is unacceptable, and the controls the FCC exercise over amateurs in the USA do at least go some way to prevent this. Julian, G4ILO --- In digitalradio@yahoogroups.com, "iv3nwv" wrote: > > Of course we need to regulate the access to our bands. > But should we need to comply with rules that has been written tens years ago? > What forbid us to take on our shoulder the weight of experimenting something > more modern than a RTTY technology which is based on what has been > experimented almost one century ago? > > Are we cows? Should we not exploit the knowledges which matured in these last > years? Should we be constrained to collect vacuum tube receivers and show > them proudly to our retired friends? > Should we ignore that a HF channel is a smart object with its delay and > doppler spread. > What kind of experiments could we do if we are allowed to make experiments > which pretend we are still in the '60s? > How could we claim that the amateur radio service could bring innovation in > communications if we are not allowed to test our ideas?
Re: [digitalradio] Re: ARRL/FCC Announcement about ROS
Nico, Does the American Radio Relay League and U.S. Federal Communications Commission have representation and/or jurisdiction over you and your license to operate your Ham station within your country and whether or not you are authorized to use an emission determined to be spread spectrum communications on those frequencies below 222 MHz? Howard W6IDS Richmond, IN EM79NV - Original Message - From: "iv3nwv" To: Sent: Thursday, March 04, 2010 8:09 PM Subject: [digitalradio] Re: ARRL/FCC Announcement about ROS > > > --- In digitalradio@yahoogroups.com, Dave Wright wrote: >> >> http://www.arrl.org/news/stories/2010/03/04/11377/?nc=1 > > Quoted: > > The ARRL supports -- as one of the basic purposes of Amateur Radio -- the > experimentation and advancing the technical skills of operators. The > development and use of any new mode is exciting to many amateurs, and the > League encourage amateurs to experiment within the parameters of the rules; > however, the ARRL also reminds US licensees that according to Section 97.307, > spread spectrum communications are only permissible in the US on frequencies > above 222 MHz. > > Uhm, it looks like the same declaration Pontius Pilate (see i.e. > http://en.wikipedia.org/wiki/Pontius_pilate) released to the community 2010 > years ago. > Similar things occurred to Giordano Bruno, a phylosopher which has been > evaporated in a public pyre some centuries ago by our local institutions. > > Of course we need to regulate the access to our bands. > But should we need to comply with rules that has been written tens years ago? > What forbid us to take on our shoulder the weight of experimenting something > more modern than a RTTY technology which is based on what has been > experimented almost one century ago? > > Are we cows? Should we not exploit the knowledges which matured in these last > years? Should we be constrained to collect vacuum tube receivers and show > them proudly to our retired friends? > Should we ignore that a HF channel is a smart object with its delay and > doppler spread. > What kind of experiments could we do if we are allowed to make experiments > which pretend we are still in the '60s? > How could we claim that the amateur radio service could bring innovation in > communications if we are not allowed to test our ideas? > > Questions. I'm just asking myself these simple questions. > I'd be sad if they hurt someone sensitivity. That's not my scope. > I'm just trying to imagine our future. > > 73s > Nico / IV3NWV
[digitalradio] Re: ARRL/FCC Announcement about ROS
--- In digitalradio@yahoogroups.com, Dave Wright wrote: > > http://www.arrl.org/news/stories/2010/03/04/11377/?nc=1 Quoted: The ARRL supports -- as one of the basic purposes of Amateur Radio -- the experimentation and advancing the technical skills of operators. The development and use of any new mode is exciting to many amateurs, and the League encourage amateurs to experiment within the parameters of the rules; however, the ARRL also reminds US licensees that according to Section 97.307, spread spectrum communications are only permissible in the US on frequencies above 222 MHz. Uhm, it looks like the same declaration Pontius Pilate (see i.e. http://en.wikipedia.org/wiki/Pontius_pilate) released to the community 2010 years ago. Similar things occurred to Giordano Bruno, a phylosopher which has been evaporated in a public pyre some centuries ago by our local institutions. Of course we need to regulate the access to our bands. But should we need to comply with rules that has been written tens years ago? What forbid us to take on our shoulder the weight of experimenting something more modern than a RTTY technology which is based on what has been experimented almost one century ago? Are we cows? Should we not exploit the knowledges which matured in these last years? Should we be constrained to collect vacuum tube receivers and show them proudly to our retired friends? Should we ignore that a HF channel is a smart object with its delay and doppler spread. What kind of experiments could we do if we are allowed to make experiments which pretend we are still in the '60s? How could we claim that the amateur radio service could bring innovation in communications if we are not allowed to test our ideas? Questions. I'm just asking myself these simple questions. I'd be sad if they hurt someone sensitivity. That's not my scope. I'm just trying to imagine our future. 73s Nico / IV3NWV
