Ric, You have discovered the lost band...6M. Well for that matter 10M and 6M FM.
Going back to my LMR (at the time just commercial 2-way radio) dispatch days, motorola had a formula that said two stations running 30 watts at 30 ft could operate 30 miles. 15 miles to a mobile and that was in the 30-50 MHz band. Well, I much better than that. Typically was 30 miles from a 30 ft antenna with the base station running 50-100 watts around 32 -37 MHz and slightly less at 47 MHz. 6m meters using very old commercial FM units got 25+ miles mobile to mobile. And on 10M, 30-40 miles was not uncommon. I am a huge beliver in using 10M and 6M FM for out to 30-40 miles and a good HF NVIS antenna for beyond ground wave. $0M day and 75/80 at night and that will always be more of a NVIS challange than 40M daytime. Take a look at this SuperNVIS antenna. http://www.hamuniverse.com/supernvis.html I REALLY works as advertised. 73, Walt/K5YFW Rick wrote: > I tend toward having solutions to the more extreme situations, but I am > probably more of an exception. With our summer flood disaster, our > immediate area did not have a communications emergency, but it could > have happened. Across the Mississippi River in SE MN, they did have > worse conditions. We did have some areas that had loss of electricity > for up to 4 days which is very serious for dairy farming, if you do not > have the necessary back up generator which has to be quite large these > days. I was lucky (sort of) since I live on the ridge top and did not > have severe flooding, although with the windstorm that took out dozens > of trees across fence lines, it was still no fun. Because our power was > off for about 18 hours and we were out of state at the time, we > personally came close to a crisis since that is pushing the limit of how > long we can tolerate not having water for cattle during hot weather. If > we had gone into a communications emergency we would have been able to > help on a limited basis, but it surprised me how impaired we were with > our own problems. > > Now I am not clear on what you are referring to with low S unit signals > for various modes. For Section and regional distances this would not be > associated with sunspots, would it? If we want to communicate outside of > our immediate area, using amateur frequenices, we would have to do this > on HF NVIS for the most part. As you probably are aware, the FoF2 can > change drastically, and particularly will go quite low at night. Right > at this moment past 10 pm, most of the U.S. is barely able to use 160 > meters for NVIS operation since the FoF2 is so low. But other times it > can go much higher, even above 7 MHz, so you have to be flexible. > > As I have discovered, actual groundwave is extremely limited on even the > HF bands, and on 75 meters will be only 15 miles or so unless you are > running verticals with excellent ground planes and perhaps with some > power over 100 watts. > > That is why the interest in working more with 6 and especially 2 meters > for digital modes. Most new rigs tend to have 100 watt 6 meter output so > that might be a practical solution in some cases, but as some have > pointed out, 2 meter SSB often works better. > > While tactical voice is most of the communications needed locally, I > agree that if you need to get messages outside of the immediate area, > other modes may be needed. CW is not exactly a dying mode, but it is > drastically less used by new hams. None of my students in the past few > years have the slightest interest in CW and that includes upgrades to > General and Extra. It is fairly easy to connect up a laptop to an HF rig > that can operate SSB, but the power requirement is significant. If we do > not have generator power, things are probably critical and even having a > low powered rig would be of limited use since you might not have much > traffic to handle in such a case, unless you were located at an EOC > facility that was trying to communicate with next level of operations. > Having much lower powered computers, which we are seeing happen, may > help, although they may not run Windows OS, particularly Vista, which > requires too much computing power. That will be a challenge to solve. > > 73, > > Rick, KV9U > > HFDEC (Hams for Disaster and Emergency Communication) Yahoogroup discussion > > > > W2XJ wrote: > >>Those are good and insightful questions. I would not depend on the >>Internet working. While certain data centers are hardened the average >>user will not have access to those benefits. We learned in the last NYC >>black out that the telephone company is no longer maintaining generators >>and they failed in a number of places. If they are part of your back >>bone, all is lost. If you have a station associated with a large company >>(as we do) it is likely you will have a dark fiber path where the active >>points in between have redundant emergency power that works and other >>plans in effect to harden to relay points. When this infrastructure does >>work, Amateur radio is less important. When everything fails there is a >>need for the most basic communications. I am not sure about your >>location but we are basically getting CW PSK31 and RTTY at S0 to S1 due >>to the low sunspots. I would agree that if RTTY and/or PSK31 were part >>of the hardware solution in a rig they, too, would be a part of the mix. >>I consider bare bones communications to be a low power battery powered >>radio with no external infrastructure or equipment. If you subscribe to >>that model than the modes I described are the only practical ones as of now. >> >> >> >>Rick wrote: >> >> >>>Quite a few emergency planners are counting on the internet staying >>>operational except in the immediate disaster area. As an example, our >>>ARRL Section leader wants members to move all digital to Winlink 2000 >>>and is focusing most resources to developing an interlinked repeater >>>system for voice and digital although I have not heard how this is being >>>done. They even have "nets" that work through Winlink 2000 since many >>>ARES members are Technician class licensees and can not operate lower >>>(NVIS) HF bands with voice or digital. >>> >>>While there are fewer and fewer chances of losing telecommunications >>>infrastructure for very long, it does occur. At that point, many of >>>these systems may not function since they are based upon many things >>>continuing to work. Some of the more foresightful emergency planners >>>(not necessarily ARES/RACES) in my area, realize that even repeaters are >>>not a sure thing either and have actually done exercises over >>>multi-county distances without them. >>> >>>Do you really see much of a use for CW, other than longer distance >>>messaging, perhaps via NTS? Even that is rarely done from the little >>>traffic that I tend to see coming out of disaster areas. There may or >>>may not be a simultaneous communications emergency, so that changes the >>>calculus too. Other than myself, I would be hard pressed to list any >>>other hams in my county who have at least some CW skill and are involved >>>with emergency communication. >>> >>>There are several things that I want to explore in the coming year: >>> >>>- whether or not the ARQ PSK modes will be competitive with ARQ ALE/FAE >>>400. Maybe both? Maybe the developers who will be coming up with a >>>Windows version of flarq could consider other modulation waveforms? >>> >>>- how effective will 2 meter SSB work between mobiles and base stations >>>using voice and digital modes compared to HF NVIS operation. Even with >>>extremely difficult terrain such as we have in this area. >>> >>>73, >>> >>>Rick, KV9U >>> >>> >>> > > > > > Announce your digital presence via our Interactive Sked Page at > http://www.obriensweb.com/drsked/drsked.php > > > View the DRCC numbers database at > http://groups.yahoo.com/group/digitalradio/database > > Yahoo! Groups Links > > > > >
