Re: [digitalradio] 30 Meter digital
My use of the band is mostly based upon propagation and, as you pointed out, minimal competition with other stations. This is particularly important with non-cw digital modes since they are typically much wider than cw and can not tolerate too much overlap in interference. Here in the U.S. could you use it for digital voice? The FCC made a determination that DV and analog voice are considered ... voice, and since voice is not permitted on the band for us, we could not use such a mode. Which is a bit strange when you consider that someone listening to the raw data would have no way of knowing if it was voice or other kind of of data. Even if we move toward bandwidth, rather than mode bandplans, it appears that modes will still play an important part. And in the past few months, I would have to say that I am much less supportive of segregation by bandwidth since many of the modes simply do not play well together. In particular, digital modes are severely impacted by even slight interference from modes such as SSB voice. This has become more noticeable on bands such as 40 meters with stations outside of the U.S. going down low in the band, even in what has been mostly digital data watering holes. For daytime range, the 30 meter band goes farther than 40 meters, so 1000 mile contacts are quite reasonable. 73, Rick, KV9U Andrew O'Brien wrote: I was reading the 30M Digital Group web page ( http://www.30meterdigital.org/ ) and thinking a bit... Much of what is posted there makes sense to many of the people that are avid users of the digitalradio Yahoo group. The band is not crowded with contests, there is less competition with other modes, etc, etc. So, perhaps we can make more of an effort to use this band, Has anyone tried it for Digital Voice. ? Also, what typical range does the band afford in daylight and evening conditions?
Re: [digitalradio] 30 Meter digital
I wish that more radio frequencies would have NVIS operation than they do in our part of the world, but the FoF2 is often way below 10 MHz so 30 meters can not be used. At 0930 Local time, the FoF2 is only 2 MHz across much of the U.S. so hams would only have 160 meters available. I notice that there is a small patch in Alaska that is 1 MHz so you could not use any of the HF or MF ham bands for NVIS right now. That is a clear case for why VHF modes can be a great help. 73, Rick, KV9U Walt DuBose wrote: Andy, A couple of years ago a friend and I played around on 30M with CW an found that a close ground mounted dipole with reflector makes a GREAT NVIS antenna and we had contacts from 50-75 miles close in out to 2,000+ miles. The dipole was put up at the measured 50 ohm feedpoint heigth and there were three reflectors under the dipole all 20% longer than the dipole and all tied together. 100 watts CW down to 10 watts just banged in all the time. Walt/K5YFW
Re: [digitalradio] 30 Meter digital
It is my belief that if voice of the same bandwidth were allowed everwhere data is allowed, the data segments of the bands would be overrun with phone stations using DV. Phone is the easiest to operate and obviously the preferred mode. During the bandwidth petition discussions, it became clear that the phone people wanted to take over as much space as they could, which is understandable, since the phone bands are always overcrowded. I don't pretend to know the real reasoning behind the FCC determination that DV is phone (just like analog voice), but practically, it currently serves to protect digital mode operators from being overrun by a multitude of phone operators. In light of the fact that you can sometimes copy an analog phone signal through another analog phone signal, but cannot do that with DV, I think we are fortunate that the FCC has taken the position they have. Skip KH6TY - Original Message - From: Rick [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, December 22, 2007 10:13 AM Subject: Re: [digitalradio] 30 Meter digital My use of the band is mostly based upon propagation and, as you pointed out, minimal competition with other stations. This is particularly important with non-cw digital modes since they are typically much wider than cw and can not tolerate too much overlap in interference. Here in the U.S. could you use it for digital voice? The FCC made a determination that DV and analog voice are considered ... voice, and since voice is not permitted on the band for us, we could not use such a mode. Which is a bit strange when you consider that someone listening to the raw data would have no way of knowing if it was voice or other kind of of data. Even if we move toward bandwidth, rather than mode bandplans, it appears that modes will still play an important part. And in the past few months, I would have to say that I am much less supportive of segregation by bandwidth since many of the modes simply do not play well together. In particular, digital modes are severely impacted by even slight interference from modes such as SSB voice. This has become more noticeable on bands such as 40 meters with stations outside of the U.S. going down low in the band, even in what has been mostly digital data watering holes. For daytime range, the 30 meter band goes farther than 40 meters, so 1000 mile contacts are quite reasonable. 73, Rick, KV9U Andrew O'Brien wrote: I was reading the 30M Digital Group web page ( http://www.30meterdigital.org/ ) and thinking a bit... Much of what is posted there makes sense to many of the people that are avid users of the digitalradio Yahoo group. The band is not crowded with contests, there is less competition with other modes, etc, etc. So, perhaps we can make more of an effort to use this band, Has anyone tried it for Digital Voice. ? Also, what typical range does the band afford in daylight and evening conditions? No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.17.6/1192 - Release Date: 12/21/2007 1:17 PM
Re: [digitalradio] 30 Meter digital
Skip, It is almost for sure that if the FCC equated DV as being similar to any other digital mode, that DV would not take over the ever decreasing size of the text digital portions of the HF bands. There are several reasons: - the lower portions of the bands, historically used for the earliest text digital mode based on wetware decoding will likely see further reductions in that mode (CW), except during contest periods since almost no new hams are acquiring even basic CW skills, much less proficiency. This will allow for more space for text digital, assuming that text digital will be segregated in that manner. - since DV is likely to never be competitive with analog SSB for weak signals as analog due to the practical limitations of science. - if digital modes did increase in popularity, which would primarily be voice DV, there would be tremendous pressure to segregate digital and analog modes by a sizable majority of radio amateurs. And it works both ways, as you well noted, analog SSB is a serious hindrance to digital modes in general. - some phone bands are underutilized now, such as on 80 meters, with few stations on the lower end of the voice sub bands and yet CW and digital can be quite crowded in a space that is well under half of what we previously had. (And I admit was underutilized with that mix too). Unless we eventually go to bandwidth based bandplans, and at the same time do not segregate by mode (especially voice modes, whether analog or digital), then it would be entirely appropriate for hams to use narrow voice modes for spectrum conservation and do it in the appropriate bandwidth areas. Based upon comments made by Dave Sumner in the past, I am not sure that will be supported by ARRL, since he seems to suggest that even if we have bandwidth limits, we will not necessarily mix modes. In fact, it was at that point that I was no longer as supportive of the withdrawn ARRL proposals, because it will still not allow us the ability to use voice and data intermixed on the HF bands (even if only in small areas) which I consider to be one of the most unfortunate effects of our current rules. The best band plans are those that allow for the best use of a shared resource. If one part of the band is congested and another part is under utilized, that means the planning is flawed. And since conditions and events constantly vary, the best regulations are the minimum necessary to make more efficient use of the bands for the maximum number of shared resource users. 73, Rick, KV9U kh6ty wrote: It is my belief that if voice of the same bandwidth were allowed everwhere data is allowed, the data segments of the bands would be overrun with phone stations using DV. Phone is the easiest to operate and obviously the preferred mode. During the bandwidth petition discussions, it became clear that the phone people wanted to take over as much space as they could, which is understandable, since the phone bands are always overcrowded. I don't pretend to know the real reasoning behind the FCC determination that DV is phone (just like analog voice), but practically, it currently serves to protect digital mode operators from being overrun by a multitude of phone operators. In light of the fact that you can sometimes copy an analog phone signal through another analog phone signal, but cannot do that with DV, I think we are fortunate that the FCC has taken the position they have. Skip KH6TY
Re: [digitalradio] 30 Meter digital
Rick, I prefaced my comment with It is my belief that if voice of the same bandwidth were allowed everwhere data is allowed, the data segments of the bands would be overrun with phone stations using DV. Perhaps it is not clear what I meant. For example, if someone comes up with a DV of 300 hz bandwidth, it will quickly be widely used anywhere 300 hz bandwidth signals are allowed, and the crush of phone users will leave little space for modes like MFSK16 of the same bandwidth to operate, simply because there will be so many people wanting to use phone instead of another digital mode, like MFSK16, but that is just my personal belief. If there were a DV mode the same width as PSK31, then the same would prove true, except that there are more spaces to use PSK31, because of its narrow bandwidth, than there are digital operators looking for space (right now, but changing). In fact there already is a sort of narrowband DV in my DigiTalk program for the blind, which speaks the PSK31 text (at 50 wpm text-to-speech), but, because going the other way (speech-to-text), still has a 5% translation error rate at best, speaking must still be done by typing, and that is a deterrent to many who might use PSK31 if they could just speak into a mike and have errorless text go out over the air. As you point out, some sort of planned segregation is going to be inevitable on shared bands. With phone and CW, there was a common language for everyone, and sharing was possible by QRL or other Q signals on CW or the equivalent on phone, but that sharing technique is useless when one mode does not hear or understand another. We have yet to experience what it will be like if everyone uses DV, there is not enough space to hold everyone, and someone accidentally starts up on your frequency because propagation was such he thought it was clear and did not happen to choose an alternate clear frequency he could QSY to if he could just understand a request to do so. I believe the thing that makes it possible for PSK31 to have a space, for example, is only that there is no true 31.25 Hz-wide phone mode. Of course, the more narrow the mode, the more stations that will fit in any given slice of spectrum, so it is advantageous to have the most narrow modes possible so there is room for as many stations as possible. At some point, there will be plenty of space, depending upon the demand, even if everyone used a voice mode that is only 31.25 Hz wide. For example, if every RTTY contester only used PSK63, there would probably be more than enough space so that during contests, RTTY stations would not have to spread out so much. There was a psychological experiment some years ago in which scientists set up two cages of rats, one overcrowded and one just at capacity. The rats in the overcrowded cage ate each other until they were no longer overcrowded. Skip KH6TY It is almost for sure that if the FCC equated DV as being similar to any other digital mode, that DV would not take over the ever decreasing size of the text digital portions of the HF bands. There are several reasons: - the lower portions of the bands, historically used for the earliest text digital mode based on wetware decoding will likely see further reductions in that mode (CW), except during contest periods since almost no new hams are acquiring even basic CW skills, much less proficiency. This will allow for more space for text digital, assuming that text digital will be segregated in that manner. - since DV is likely to never be competitive with analog SSB for weak signals as analog due to the practical limitations of science. - if digital modes did increase in popularity, which would primarily be voice DV, there would be tremendous pressure to segregate digital and analog modes by a sizable majority of radio amateurs. And it works both ways, as you well noted, analog SSB is a serious hindrance to digital modes in general. - some phone bands are underutilized now, such as on 80 meters, with few stations on the lower end of the voice sub bands and yet CW and digital can be quite crowded in a space that is well under half of what we previously had. (And I admit was underutilized with that mix too). Unless we eventually go to bandwidth based bandplans, and at the same time do not segregate by mode (especially voice modes, whether analog or digital), then it would be entirely appropriate for hams to use narrow voice modes for spectrum conservation and do it in the appropriate bandwidth areas. Based upon comments made by Dave Sumner in the past, I am not sure that will be supported by ARRL, since he seems to suggest that even if we have bandwidth limits, we will not necessarily mix modes. In fact, it was at that point that I was no longer as supportive of the withdrawn ARRL proposals, because it will still not allow us the ability to use voice and data intermixed on the HF bands (even if only in small
Re: [digitalradio] 30 Meter digital
If we really could run voice on 300 Hz BW, I would support using it in a narrow digital area since I think that it is good practice to provide protection for narrow modes against the wide modes. Ironically, that is not what is currently in the FCC rules. We have very wide BW modes, running in the text digital areas of the HF bands, but you can not run narrow modes in the wide portions of the bands (the image/voice portions). I honestly think that much of this HF DV stuff is pie in the sky. It might be possible that there could be a breakthrough in digital technology which would turn things upside down but then again is that realistically going to happen? The restricted BW voice modes are pretty much following theory and the quality suffers terribly in terms of comprehension. But let's say a miracle occurs and you could get greatly improved quality with a narrow bandwidth. If that happened, we would see a migration to the narrower voice modes which will free up a lot of bandwidth. But I don't think this will happen as DV will be difficult, if not impossible to operate with other signals in the passband. This may work with military/commercial channels and high power, but it just does not have the technological edge that SSB has for weak signal, high QRM, shared frequencies, that are so typical on the HF ham bands. As you point out, there are hams who read the text back with a voice and it has been around for many years. If you recall, not long ago (year or so?) there was a QST article about a ham sending PSK31 via a speech to text conversion so that is also being done, at least on a limited basis. Whenever new modes come along that really have a compelling value, they are eventually adopted when the cost/benefit ratio makes it possible to do so. Either for widespread use if they stand the test of time, or sometimes for niche purposes as we are seeing with some of the text digital modes. I rarely get involved in contesting, but it appears that RTTY works better for fast exchanges. At least it may be perceived that way. I have tried PSK31 for casual quick contacts such as Field Day and found it impractical for me to work many stations compared to voice. I have not tried PSK63, (other than casual tests) but hope to use this for a very different purpose when the MS Windows version is made available for the emergency communication program that is currently being used on Linux. Are you personally involved in that project as you were with the Linux version? 73, Rick, KV9U kh6ty wrote: Rick, I prefaced my comment with It is my belief that if voice of the same bandwidth were allowed everwhere data is allowed, the data segments of the bands would be overrun with phone stations using DV. Perhaps it is not clear what I meant. For example, if someone comes up with a DV of 300 hz bandwidth, it will quickly be widely used anywhere 300 hz bandwidth signals are allowed, and the crush of phone users will leave little space for modes like MFSK16 of the same bandwidth to operate, simply because there will be so many people wanting to use phone instead of another digital mode, like MFSK16, but that is just my personal belief. If there were a DV mode the same width as PSK31, then the same would prove true, except that there are more spaces to use PSK31, because of its narrow bandwidth, than there are digital operators looking for space (right now, but changing). In fact there already is a sort of narrowband DV in my DigiTalk program for the blind, which speaks the PSK31 text (at 50 wpm text-to-speech), but, because going the other way (speech-to-text), still has a 5% translation error rate at best, speaking must still be done by typing, and that is a deterrent to many who might use PSK31 if they could just speak into a mike and have errorless text go out over the air. As you point out, some sort of planned segregation is going to be inevitable on shared bands. With phone and CW, there was a common language for everyone, and sharing was possible by QRL or other Q signals on CW or the equivalent on phone, but that sharing technique is useless when one mode does not hear or understand another. We have yet to experience what it will be like if everyone uses DV, there is not enough space to hold everyone, and someone accidentally starts up on your frequency because propagation was such he thought it was clear and did not happen to choose an alternate clear frequency he could QSY to if he could just understand a request to do so. I believe the thing that makes it possible for PSK31 to have a space, for example, is only that there is no true 31.25 Hz-wide phone mode. Of course, the more narrow the mode, the more stations that will fit in any given slice of spectrum, so it is advantageous to have the most narrow modes possible so there is room for as many stations as possible. At some point, there will be plenty of space,
Re: [digitalradio] 30 Meter digital
Rick, comprehension. But let's say a miracle occurs and you could get greatly improved quality with a narrow bandwidth. If that happened, we would see a migration to the narrower voice modes which will free up a lot of bandwidth. That is the hoped-for goal. How we are able to handle modes that cannot communicate sharing has to be developed. As you point out, there are hams who read the text back with a voice and it has been around for many years. If you recall, not long ago (year or so?) there was a QST article about a ham sending PSK31 via a speech to text conversion so that is also being done, at least on a limited basis. I worked him on the air by accident and was very impressed, until I emailed him and he admitted to editing the text to take out the errors before sending! :-) A 5% error rate means one word in 20 is going to be pronounced wrong. I rarely get involved in contesting, but it appears that RTTY works better for fast exchanges. At least it may be perceived that way. I have tried PSK31 for casual quick contacts such as Field Day and found it impractical for me to work many stations compared to voice. That is why we devoloped PSK63 - for contesting speed equal to RTTY, but with less fills and less bandwidth consumption. It is just as fast as RTTY overall. I have not tried PSK63, (other than casual tests) but hope to use this for a very different purpose when the MS Windows version is made available for the emergency communication program that is currently being used on Linux. Are you personally involved in that project as you were with the Linux version? Yes, I am the project manager and co-developer. Everything is looking good and almost ready for beta testing to uncover any problems that have not shown up yet. I am also net control for a 2m PSK63 ragchew net on 144.144 MHz, USB,1500 Hz tone frequency, which has been meeting twice a week for over a year and a half now. We use PSK63 instead of FM for greater range and instead of PSK31 for better multipath interference resistance and less drift problems. We use the extra speed for net control to replay all incoming transmissions at 100 wpm, so that everyone on the net gets to know what anyone else has said in case they are not in a station's beampath. There is no directional calling by net control as there is on other VHF nets. All stations beam toward net control, and I use a special high-gain, bidirectional, horizontally-polarized antenna covering 88 degrees to the front and 88 degrees to the back so everyone is able to copy me without my having to rotate. Most people type about 20 wpm and for about 2 minutes on their turn, so it takes only 24 seconds on the average to retransmit the incoming text for all to enjoy. Range using PSK63 is 100 to 200 miles, depending upon the elevation and antenna gain of the distant station. This is another thing PSK63 is good for. The European PSK Club, which heavily promotes PSK63, just finished their annual 24-hour QSO party on November 18 and the passband was filled with PSK63 stations for 24 hours. Andy can elaborate. You might give it a try next time and compare the speed of exchanges to RTTY contests, of which there are many. 73, Skip KH6TY
Re: [digitalradio] 30 Meter digital
Andrew O'Brien wrote: I was reading the 30M Digital Group web page ( http://www.30meterdigital.org/ ) and thinking a bit... Much of what is posted there makes sense to many of the people that are avid users of the digitalradio Yahoo group. The band is not crowded with contests, there is less competition with other modes, etc, etc. So, perhaps we can make more of an effort to use this band, Has anyone tried it for Digital Voice. ? Also, what typical range does the band afford in daylight and evening conditions? Andy, A couple of years ago a friend and I played around on 30M with CW an found that a close ground mounted dipole with reflector makes a GREAT NVIS antenna and we had contacts from 50-75 miles close in out to 2,000+ miles. The dipole was put up at the measured 50 ohm feedpoint heigth and there were three reflectors under the dipole all 20% longer than the dipole and all tied together. 100 watts CW down to 10 watts just banged in all the time. Walt/K5YFW
