[digitalradio] FCC - Spread Spectrum NPRM
Regarding Spread Spectrum Notice of Proposed Rule Making (NPRM) http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 It proposes to reduce some of the restrictions on Spread Spectrum but unfortunately does nothing about permitting the use at HF and VHF of SS modes that completely fit within the bandwidth of a phone signal (say 3 kHz on HF and 15 kHz on VHF). It says comments can be filed on or before 30 days after date of publication in the Federal Register. Instructions on how to file comments on the NPRM only are listed on pages 6-7 in the NPRM. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf Electronic Comment Filing System http://www.fcc.gov/cgb/ecfs/ 73 Trevor M5AKA
Re: [digitalradio] FCC - Spread Spectrum NPRM
Extensive tests on 70cm using ROS 16 baud spread spectrum have been disappointing. ROS appears to be unable to survive the Doppler shift and Doppler induced flutter so prevalent on that band. The hope was that ROS 16 baud would make traditional communications possible that were difficult on SSB phone because of the Doppler shift and flutter. However, the tests show that Olivia 32-1000, in half the bandwidth, and Olivia 16-500, produce print when ROS only prints garbage. This, together with the fact that both stations must be within 400 Hz of each other before even trying to communicate, instead of being able to tune with the mouse as is possible with Olivia, makes it very difficult to achieve a QSO on 70cm using ROS. Olivia has therefore proven to be much more successful than ROS on UHF. Tests using the ROS 1 baud variation will be made next, but the slow speed of that mode is more suited to EME communications than normal QSO's. In two weeks of monitoring ROS 16 baud on 20m, there has been only one observed case where the S/N was under where Olivia 32-1000 can decode, so even on HF, there does not appear to be any justification for using such a wide mode, even if spread spectrum were permitted on HF in the US. Just use Olivia or MFSK16 instead when band conditions are poor. The new narrow band ROS modes were not tested, since a mode to do better than Olivia is what is needed, and the spread spectrum mode of ROS held the best hope. As it stands, only CW is better than Olivia under the worst conditions, and only when copying by ear, but CW is only a little better than Olivia 16-500. We have also found that the more narrow Olivia modes (i.e. 500 Hz wide) are also too greatly disturbed by Doppler to be useful either. If anyone is within 200 miles of FM02, has 100 watts and an antenna gain of 17 dBi or greater, and would like to try ROS 16 baud on UHF, I am available to do that. I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. 73 - Skip KH6TY Trevor . wrote: Regarding Spread Spectrum Notice of Proposed Rule Making (NPRM) http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 It proposes to reduce some of the restrictions on Spread Spectrum but unfortunately does nothing about permitting the use at HF and VHF of SS modes that completely fit within the bandwidth of a phone signal (say 3 kHz on HF and 15 kHz on VHF). It says comments can be filed on or before 30 days after date of publication in the Federal Register. Instructions on how to file comments on the NPRM only are listed on pages 6-7 in the NPRM. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf Electronic Comment Filing System http://www.fcc.gov/cgb/ecfs/ http://www.fcc.gov/cgb/ecfs/ 73 Trevor M5AKA
Re: [digitalradio] FCC - Spread Spectrum NPRM
I read the proposed rule making and did not find any reference to frequency/band. So, where is it saying SS is allow but only on 220Mhz and above ? On Thu, Mar 18, 2010 at 6:11 PM, KH6TY kh...@comcast.net wrote: Extensive tests on 70cm using ROS 16 baud spread spectrum have been disappointing. ROS appears to be unable to survive the Doppler shift and Doppler induced flutter so prevalent on that band. The hope was that ROS 16 baud would make traditional communications possible that were difficult on SSB phone because of the Doppler shift and flutter. However, the tests show that Olivia 32-1000, in half the bandwidth, and Olivia 16-500, produce print when ROS only prints garbage. This, together with the fact that both stations must be within 400 Hz of each other before even trying to communicate, instead of being able to tune with the mouse as is possible with Olivia, makes it very difficult to achieve a QSO on 70cm using ROS. Olivia has therefore proven to be much more successful than ROS on UHF. Tests using the ROS 1 baud variation will be made next, but the slow speed of that mode is more suited to EME communications than normal QSO's. In two weeks of monitoring ROS 16 baud on 20m, there has been only one observed case where the S/N was under where Olivia 32-1000 can decode, so even on HF, there does not appear to be any justification for using such a wide mode, even if spread spectrum were permitted on HF in the US. Just use Olivia or MFSK16 instead when band conditions are poor. The new narrow band ROS modes were not tested, since a mode to do better than Olivia is what is needed, and the spread spectrum mode of ROS held the best hope. As it stands, only CW is better than Olivia under the worst conditions, and only when copying by ear, but CW is only a little better than Olivia 16-500. We have also found that the more narrow Olivia modes (i.e. 500 Hz wide) are also too greatly disturbed by Doppler to be useful either. If anyone is within 200 miles of FM02, has 100 watts and an antenna gain of 17 dBi or greater, and would like to try ROS 16 baud on UHF, I am available to do that. I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. 73 - Skip KH6TY Trevor . wrote: Regarding Spread Spectrum Notice of Proposed Rule Making (NPRM) http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 It proposes to reduce some of the restrictions on Spread Spectrum but unfortunately does nothing about permitting the use at HF and VHF of SS modes that completely fit within the bandwidth of a phone signal (say 3 kHz on HF and 15 kHz on VHF). It says comments can be filed on or before 30 days after date of publication in the Federal Register. Instructions on how to file comments on the NPRM only are listed on pages 6-7 in the NPRM. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf Electronic Comment Filing System http://www.fcc.gov/cgb/ecfs/ 73 Trevor M5AKA
Re: [digitalradio] FCC - Spread Spectrum NPRM
Andy, As I read it, the NPRM did not disturb the current FCC ruling that spread spectrum is only allowed above 222 Mhz, so that is still in force. What it did was modify the power and power monitoring requirements. 73 - Skip KH6TY Andy obrien wrote: I read the proposed rule making and did not find any reference to frequency/band. So, where is it saying SS is allow but only on 220Mhz and above ? On Thu, Mar 18, 2010 at 6:11 PM, KH6TY kh...@comcast.net mailto:kh...@comcast.net wrote: Extensive tests on 70cm using ROS 16 baud spread spectrum have been disappointing. ROS appears to be unable to survive the Doppler shift and Doppler induced flutter so prevalent on that band. The hope was that ROS 16 baud would make traditional communications possible that were difficult on SSB phone because of the Doppler shift and flutter. However, the tests show that Olivia 32-1000, in half the bandwidth, and Olivia 16-500, produce print when ROS only prints garbage. This, together with the fact that both stations must be within 400 Hz of each other before even trying to communicate, instead of being able to tune with the mouse as is possible with Olivia, makes it very difficult to achieve a QSO on 70cm using ROS. Olivia has therefore proven to be much more successful than ROS on UHF. Tests using the ROS 1 baud variation will be made next, but the slow speed of that mode is more suited to EME communications than normal QSO's. In two weeks of monitoring ROS 16 baud on 20m, there has been only one observed case where the S/N was under where Olivia 32-1000 can decode, so even on HF, there does not appear to be any justification for using such a wide mode, even if spread spectrum were permitted on HF in the US. Just use Olivia or MFSK16 instead when band conditions are poor. The new narrow band ROS modes were not tested, since a mode to do better than Olivia is what is needed, and the spread spectrum mode of ROS held the best hope. As it stands, only CW is better than Olivia under the worst conditions, and only when copying by ear, but CW is only a little better than Olivia 16-500. We have also found that the more narrow Olivia modes (i.e. 500 Hz wide) are also too greatly disturbed by Doppler to be useful either. If anyone is within 200 miles of FM02, has 100 watts and an antenna gain of 17 dBi or greater, and would like to try ROS 16 baud on UHF, I am available to do that. I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. 73 - Skip KH6TY Trevor . wrote: Regarding Spread Spectrum Notice of Proposed Rule Making (NPRM) http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 http://www.arrl.org/news/stories/2010/03/18/11396/?nc=1 It proposes to reduce some of the restrictions on Spread Spectrum but unfortunately does nothing about permitting the use at HF and VHF of SS modes that completely fit within the bandwidth of a phone signal (say 3 kHz on HF and 15 kHz on VHF). It says comments can be filed on or before 30 days after date of publication in the Federal Register. Instructions on how to file comments on the NPRM only are listed on pages 6-7 in the NPRM. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-38A1.pdf Electronic Comment Filing System http://www.fcc.gov/cgb/ecfs/ http://www.fcc.gov/cgb/ecfs/ 73 Trevor M5AKA
Re: [digitalradio] FCC - Spread Spectrum NPRM
El 18/03/2010 18:11, KH6TY escribió: Extensive tests on 70cm using ROS 16 baud spread spectrum have been disappointing. ROS appears to be unable to survive the Doppler shift and Doppler induced flutter so prevalent on that band. The hope was that ROS 16 baud would make traditional communications possible that were difficult on SSB phone because of the Doppler shift and flutter. However, the tests show that Olivia 32-1000, in half the bandwidth, and Olivia 16-500, produce print when ROS only prints garbage. This, together with the fact that both stations must be within 400 Hz of each other before even trying to communicate, instead of being able to tune with the mouse as is possible with Olivia, makes it very difficult to achieve a QSO on 70cm using ROS. Olivia has therefore proven to be much more successful than ROS on UHF. I was also dissapointed on HF. To me, ROS is an incomplete solution that stands no comparison to other beter designed protocols already in use. FHSS per se is not a miraculous solution. Even when having some processing gain, is not enough to stand and recover from the real world path impairments. Tests using the ROS 1 baud variation will be made next, but the slow speed of that mode is more suited to EME communications than normal QSO's. In two weeks of monitoring ROS 16 baud on 20m, there has been only one observed case where the S/N was under where Olivia 32-1000 can decode, so even on HF, there does not appear to be any justification for using such a wide mode, even if spread spectrum were permitted on HF in the US. Just use Olivia or MFSK16 instead when band conditions are poor. The new narrow band ROS modes were not tested, since a mode to do better than Olivia is what is needed, and the spread spectrum mode of ROS held the best hope. As it stands, only CW is better than Olivia under the worst conditions, and only when copying by ear, but CW is only a little better than Olivia 16-500. We have also found that the more narrow Olivia modes (i.e. 500 Hz wide) are also too greatly disturbed by Doppler to be useful either. Perhaps what is needed is a variant with wider tones/bins, modulated at a higher speed, so path perturbations have a lesser effect. Have you tried higher bandwidth and less tones ? Maybe you can find a better compromise (it will always be a compromise, I believe) that way. If anyone is within 200 miles of FM02, has 100 watts and an antenna gain of 17 dBi or greater, and would like to try ROS 16 baud on UHF, I am available to do that. I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. Skip, please do tell us. I am particularly quite curious about the results of your tests. 73, Jose, CO2JA
Re: [digitalradio] FCC - Spread Spectrum NPRM
Hi Jose, We will be starting with tests of ROS 1 baud tomorrow but I will not have any results until next week, after we have been able to make tests over several days and under many different conditions. The tests with ROS 16 baud have been finished and our results are as I have already reported. Perhaps if the spreading were much wider, say as much a 10 kHz or 20 kHz, the result might be better, but then nobody on UHF SSB has an IF filter wider than 2.5 kHz anyway. It would probably take at least a SDR on both ends, I think, but so far those are still rare, even though they make excellent IF's for VHF and UHF transverters. So, wider spreading is just not practical. Whatever it is that is causing a raspy CW note, and raspy sounding ROS tones, must be destroying the data modulation on the carriers, but I do not know enough about the modulation technique or the autocorrelation function that ROS uses to understand why that is causing ROS to fail. Perhaps it is because EVERY tone in the bandpass is so badly distorted that autocorrelation is not possible and decoding fails (i.e. is the Doppler shift perhpas moving the carriers outside some very narrow DSP filter?). As best I can remember from my college days (50 years ago!), autocorrelation will only work if reoccurring signals are identified among random noise, but if the tones are distorted so they appear too much like the noise, correlation may not be possible. I am sure experienced communications theorists can make a better guess than I can! The Olivia tones are also raspy sounding, but Olivia survives and ROS does not. When the tones sound pure, ROS does OK, but that does not happen very often at fringe area reception on UHF, and mostly only when there is propagation enhancement. 73 - Skip KH6TY I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. Skip, please do tell us. I am particularly quite curious about the results of your tests. 73, Jose, CO2JA
Re: [digitalradio] FCC - Spread Spectrum NPRM
Skip, Just a thought, but raspy signals on VHF/UHF are usually associated with aurora. Can you correlate that? 73... Jon W1MNK PS Great discussion!! KH6TY wrote: Hi Jose, We will be starting with tests of ROS 1 baud tomorrow but I will not have any results until next week, after we have been able to make tests over several days and under many different conditions. The tests with ROS 16 baud have been finished and our results are as I have already reported. Perhaps if the spreading were much wider, say as much a 10 kHz or 20 kHz, the result might be better, but then nobody on UHF SSB has an IF filter wider than 2.5 kHz anyway. It would probably take at least a SDR on both ends, I think, but so far those are still rare, even though they make excellent IF's for VHF and UHF transverters. So, wider spreading is just not practical. Whatever it is that is causing a raspy CW note, and raspy sounding ROS tones, must be destroying the data modulation on the carriers, but I do not know enough about the modulation technique or the autocorrelation function that ROS uses to understand why that is causing ROS to fail. Perhaps it is because EVERY tone in the bandpass is so badly distorted that autocorrelation is not possible and decoding fails (i.e. is the Doppler shift perhpas moving the carriers outside some very narrow DSP filter?). As best I can remember from my college days (50 years ago!), autocorrelation will only work if reoccurring signals are identified among random noise, but if the tones are distorted so they appear too much like the noise, correlation may not be possible. I am sure experienced communications theorists can make a better guess than I can! The Olivia tones are also raspy sounding, but Olivia survives and ROS does not. When the tones sound pure, ROS does OK, but that does not happen very often at fringe area reception on UHF, and mostly only when there is propagation enhancement. 73 - Skip KH6TY I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. Skip, please do tell us. I am particularly quite curious about the results of your tests. 73, Jose, CO2JA
Re: [digitalradio] FCC - Spread Spectrum NPRM
John, The raspy sound is similar to that associated with aurora, but this far south, aurora is very rare, and the raspy tone is there almost all the time, every day, if there is no propagation enhancement. So I don't think it is caused by aurora, but if you picture how aurora looks visually, with curtains of light moving about, it makes one wonder if the tropospheric scattering is also unstable in a similar way. The general consensus is that VHF/UHF communication over the curvature of the earth (i.e. past line of sight ) is mostly by either tropospheric scattering or by ducting. What makes the medium unstable in the manner observed does not seem to be well understood. Check the Hepburn prediction page for an excellent discussion of tropospheric scattering: http://www.dxinfocentre.com/tropo.html scroll down to the bottom, past the maps, and see the links in yellow - really fascinating reading! 73 - Skip KH6TY Jon Maguire wrote: Skip, Just a thought, but raspy signals on VHF/UHF are usually associated with aurora. Can you correlate that? 73... Jon W1MNK PS Great discussion!! KH6TY wrote: Hi Jose, We will be starting with tests of ROS 1 baud tomorrow but I will not have any results until next week, after we have been able to make tests over several days and under many different conditions. The tests with ROS 16 baud have been finished and our results are as I have already reported. Perhaps if the spreading were much wider, say as much a 10 kHz or 20 kHz, the result might be better, but then nobody on UHF SSB has an IF filter wider than 2.5 kHz anyway. It would probably take at least a SDR on both ends, I think, but so far those are still rare, even though they make excellent IF's for VHF and UHF transverters. So, wider spreading is just not practical. Whatever it is that is causing a raspy CW note, and raspy sounding ROS tones, must be destroying the data modulation on the carriers, but I do not know enough about the modulation technique or the autocorrelation function that ROS uses to understand why that is causing ROS to fail. Perhaps it is because EVERY tone in the bandpass is so badly distorted that autocorrelation is not possible and decoding fails (i.e. is the Doppler shift perhpas moving the carriers outside some very narrow DSP filter?). As best I can remember from my college days (50 years ago!), autocorrelation will only work if reoccurring signals are identified among random noise, but if the tones are distorted so they appear too much like the noise, correlation may not be possible. I am sure experienced communications theorists can make a better guess than I can! The Olivia tones are also raspy sounding, but Olivia survives and ROS does not. When the tones sound pure, ROS does OK, but that does not happen very often at fringe area reception on UHF, and mostly only when there is propagation enhancement. 73 - Skip KH6TY I promised to post the results of our attempts to use ROS on UHF on this reflector, and this is what we have found. So, it looks like Olivia is currently still the best digital mode to use on UHF, VHF, or HF for normal (not EME) digital QSO's. Skip, please do tell us. I am particularly quite curious about the results of your tests. 73, Jose, CO2JA
