THE LF NOTEBOOK #38 (From THE LOWDOWN, May, 1996) The Mailbag, News and Comments About LF Radio, Etc. John H. Davis, Box 367, Warm Springs, GA 31830 -Longwave BBS - 706/672-0360 -E-mail - johnhdavis@aol.com -Fax - (706) 672-0964 -World Wide Web http://users.aol.com/lwcanews/lwcanews.html Now we know how May got its name. It signifies that winter *may* be over. At least the approach of May is bringing leaves to some of the trees. They usually all pop out in one or two days during the first week of April here in Georgia. Not this year. Even if winter isn't completely done, could we maybe persuade you folks in the Northeast to turn down the thermostats a little? The oil industry says the heating season is the reason for the 30 - 50% (!) jump in gasoline prices around here. Kind of surprised us...we thought maybe Memorial Day had come early this year, or else they were getting a head start on gouging us during the Olympics. But no, that's all still ahead of us yet. And we are trying to get everything ready for you all to come to the Olympics. Just this morning, I encountered a convoy of Olympic officials, who appeared to be driving the route of the Olympic flame. It will be coming right past the TV station and then down the mountain into Warm Springs. That may be the closest I get to the games, but it should be a treat anyway. *Online Connection Updates The Web--you can get there from here. The main LWCA club page at http://www.anarc.org/lwca/ now has a link to the more general-purpose Longwave Home Page, and vice-versa. You can get to either one from the other. The latter is at http://users.aol.com/lwcanews/lwcanews.html . New on the Longwave Home Page this month: links to the University of Alaska (sprites, blue jets, etc.) and Stanford University (whistlers and VLF propagation) for our natural radio enthusiasts, with more good stuff being added weekly. The BBS has gone to its summer schedule. Weekday hours will be roughly dusk to dawn, Georgia time, plus all day Saturdays and Sundays, weather permitting. Registration continues for the bulletin board, as well as the Computer Communication Survey. During the month of April, quite a few BBS users downloaded and completed our questionnaire, though a good percentage still need to do so. Everyone can still use the BBS free, but after May 15, unregistered users will have to log in as new users each day. Save time...register now! Download SURVEY.EXE or SURVEY.ZIP if you have a PC-compatible; or else SURVEY.TXT (carriage return at end of each line) or SURVEY.ASC (carriage return only at end of paragraphs) if you don't have a PC-compatible. *Digital Modes: Listeners Wanted This month's BPSK report from Clifford Buttschardt (C; HDO;W6HDO; Morro Bay, CA; E-mail: cbuttsch@ slonet.org) includes POM mode as well... Plain Old Morse, that is. "Here in the West we continue to have QSO's on the 1750 meter band primarily in CW as it is just fun! Of course the HDO(nul) beacon continues to operate and I would assume being heard by those in the Midwest that care to listen. At last report, Lyle Koehler was getting pages of full copy at time using a new receiver designed by him." "A number of us have been talking about a 'universal calling frequency' for use in the LOWFER band. It is somewhat of a dream that any such address exists, but we have observed that frequencies of integral 100, 500 and 900 Hertz are often used by Power Line Carriers. Noting that demodulated signals for BPSK require 800 Hz tones, carrier frequencies of 1xx.6 seem suitable." "Audio image problems have been showing up in non-image rejection designs, in addition to the fact that two way contacts are most easily gotten by stations exactly 800 Hz from the inital station. HDO(nul) will probably move to 187.600 next winter." "All kinds of synthesizers are being built, some using the DSP technique by Steve Webber (73 magazine, Dec '95). Others have been building simple units using the old fashioned CD4059 chips of years ago. As before, the watchword is stability and frequency sythesisis." "Word has been gotten that BPSK is legal on the ham bands as long as the station is attended. We will be putting on a station on 1844 KHz very soon. That frequency was selected as 800 Hz from 1843.2 KHz, which is used in the DeCarle Sigma Delta audio spectrum analyzer. Therefore, even if your setup leaks that signal, no interference will result." A signal in the amateur bands should be welcomed by those of us who need to practice using the receiving software, prior to trying it on the horrendously low level signals we can expect to find in the LowFER band. Of course, 160 meters in the spring and summer is no picnic, but it'll be a good rehearsal. From a message Cliff sent to John West and Bill de Carle recently, we learn a little bit about the C/HDO transmitter site. "The HDO(nul) beacon is now running just under one watt. I had to reduce the supply voltage to nine volts. At this level a 300 ma RF ammeter pins....this is a super site with over 100 radials on a hilltop. The signal that is produced is more than Mike Mideke was able to get with his Z beacon." One thing the BPSK project needs more than anything else is listeners. This spring and summer would be excellent times to assemble the VE2IQ Delta Sigma A/D Converter board, and practice using it with your computer and a stable receiver. There's no telling who could set the next digital DX record next winter! From The Mailbag, Take One... - So you think the average ham or LowFER antenna poses enough public relations problems in a typical neighborhood? Just imagine what it would be like if you had an Omega navigation station in your back yard. Greg Greenwood (WB6FZH/KH6, Box 1325 , Weaverville, CA 96093, E-Mail: greg6fzh@aol.com) reports on a recent local news story about this very situation: "There is an Omega transmitter site in Kaneohe, Hawaii. The antenna stretches across a valley formed by part of the Koolau Mountain range. I look at it and wonder how I could use it for a LowFER or the next 160 meter contest... But the Hawaii Department of Transportation is building another highway, complete with a tunnel through the mountains to Honolulu, near the antenna." "They have proposed building a one mile long Faraday Shield over the roadway to protect motorists from the dangers of the RF field. They cite problems with pacemakers, vehicle computers, and other devices. The project is estimated at 2.5 million dollars, and would be in the form of a wire cage around one mile of State Highway 3. The State and Federal governments are again looking into potential health problems." "The biggest user of the Omega system (according to the TV news) is the US Weather Bureau, that launches weather balloons, to interface their electronics to Omega, and send data that is entered into the computerized system used for prediction of weather and hurricane warnings." "I am new to the area, and interested in VLF, BCB and HF primarily. I have not unpacked my VLF RX, and have a feeling since I can see the antenna from near my house, I can probably hear a lot without even turning the radio on." Greg hopes to put a beacon on the air at Weaverville, Trinity County, between Redding and Eureka, CA, this year, probably both LowFER and MedFER. He is still working on the antenna design. "Restricted antenna options at the Kaneohe location will keep LowFER/MedFER antennas at a low profile," he says, and, "would appreciate any suggestions of antenna designs." - Brice Anderson (BA, IE; Lancaster, IL) only had one beacon to report receiving last month, YHO, but it came in well. His own beacon quit on April 3 with an open emitter biasing diode. It was replaced with two in series, to push the amp farther into Class C. Weather had gotten to a phono plug connection, too, but once that was resolved, BA was back on the air. Its PVC pipe mast has survived two winters now, and Brice eventually plans to write it up for the Lowdown. It was designed to be put up easily by one person, and is inexpensive too. - Lyle Koehler (LEK, MIN, K0LR; Aitkin, MN): "I haven't done much listening on LF except to check for daytime LowFER signals. BK, RM and ART (when it's on) still come in very well. 0KVL seems to have an intermittent transmitter problem, and SAM is very weak on the temporary antenna. The only skywave signal heard since early March has been OK. Bill Bower's new antenna is doing very well." - Bill de Carle (VE2IQ) wrote to let us know some popular .ZIP files from his BBS are now available for downloading directly via Internet. They include COHERENT, his FFT spectrum analyzer, and other goodies. "Just point a web browser at: http://w3.ietc.ca/home/bill/bbs.htm and click on the file you want to download....It might help some folks save on long distance charges," he notes. - James Taylor got it wrong. Apparently the song should have been "I've Seen Fire and I've Seen Hail." Bill Cantrell (TEXAS, WD5CVG; Haslet, TX; E-mail: Cantrell_Bill@macmail1.fwrdc.rtsg.mot.com) sent word earlier of an exciting time out on the prairire, and then an update just as this issue was being readied for the printers. "Ah, the joys of country living . . . You've probably seen news accounts of all the grass fires we had in north Texas. Well, the TEXAS beacon survived a grass fire that swept through our neighborhood a few weeks ago. We keep the grass mowed extremely short in the winter, which is why no houses burned, but my entire 2.5 acres went up in flames. (I'm thinking about installing a heat sensor in the beacon so it will switch to sending SOS next time -- just kidding!)" "I found out how futile it is to try to fight a grass fire with a garden hose. The smoke alone drove us back inside the house. We grabbed the kids, the pets, and the photo albums and jumped in the cars to flee, just a few steps ahead of the fire. Fortunately no damage done other than burned fencing." "I have located an insulator for the base, so the new tower should be going up in a few weeks, just in time for our tornado season, followed by our flood season." But the best laid plans do go astray. The April 19 update: "I forgot to mention that we have a hail season in between the grass fire season and the tornado/flood season. It knocked out my base loading coil, so the TEXAS beacon is off of the air until we rebuild it this summer." - David Goncalves (2 Overlook Circle, Milford, MA 01757; tel: 508-478- 3283) plans a 1750 meter station, but budget considerations may stretch the project out. Meantime, he has some items for sale: old vacuum tubes (RCA UX280, RCA UY227, DeForest Audion 427, Cunningham C335); a VIC 20 with manual, program tapes, tape drive, video connector; and a World War II era BC-1206-CM receiver for 195-410 kHz (with partial manual, good tubes; some caps may need replacing). - A note from Loggings columnist Robert Montgomery a couple of weeks ago started off with "I see you have survived another winter." That's debatable, but I do agree with his further thoughts. "I think under NAFTA, we should get warm air from Mexico and not as much cold air exported by Canada." He reports receiving TH from Colts Neck, NJ, "all day long. 80 miles from here. Nice signal. But no others." - Nils Young (WB8IJN; Medway, OH; E-mail: nyoung@nova.wright.edu) wrote at the end of February, but I misplaced the message in one of the more obscure subdirectories on the computer. I very much regret not having it for the April column, because now I have to omit some of the references to space aliens (prompted by Nils' watching a recent PBS Nova broadcast on abduction reports). Oh well. The possible beacon frequencies he mentioned in his first letter this winter turned out not to be practical. "I'm looking at putting beacons up on 173.75 kHz, 1630.5 kHz and maybe, 7.04 kHz. The 7.04 kHz frequency is particularly inticing, since a 1/4 L wire would only reach from here to about the Indiana state line. If I could get a trenching machine, I could run along I-70 and bury some wire to make 1/2 of a buried loop....Seriously, right now I'm just getting the stuff to work on 173.75. It'll probably be ready to go in time for summer thunderstorms." "But the good news: I heard YHO a couple nights in a row (24/25 Feb) from about midday local on into the evening. I called Bill's house and his wife told me that he'd gone off with Bill Diggins (XJ) to a hamfest." "Reading about all these other folks hearing stuff miles off into the middle of day or night kinda gets me fired up. I must be doing something right to hear XJ or YHO. But I'm definitely doing something wrong 'cause I can't hear anyone else. Except for the aliens who contact me in my sleep." From The Mailbag, Take Two... (As you know, I normally refrain from editorial responses to letters. Seldom do I add more than a note of thanks or other brief comments. We have one this time, however, for which I believe an exception is warranted, because it raises concerns that other readers may want to have clarified.) -Dave Rickett (15600 Del Prado Drive, Hacienda Heights, CA 91745; e-mail: DaveR73769@aol.com) writes: "A recent edition of LOWDOWN reported on a Part 15 signal detected in Colorado and Minnesota originating in California. LOWDOWN has not described the special circumstances that would make this claim credible. Some of the reported aspects of the reported detection such as enhance reception at twilight times in the east to west direction, no audible detection, and 'pages of error free copy' suggest a skeptical attitude." "From what information is described, it appears that both the radiating antenna and the special receiving hardware and software originate from a single source namely Cuesta College in San Luis Obispo, CA. Was this a student project? Is the identifier 'HDO' programmed into the special receiving hardware or software? A straightforward test of transmitting the headline of a major newspaper on the same day would help to eliminate the possibility of programmer bias." "A Part 15 signal originating in California would be expected to have a strength in Colorado of one tenth of thermal noise and in Minnesota three quarters less. Verification was not reported of special conditions such as high radiation efficiency from the transmitting antenna, unusual propagation effects, very high gain reception, or very narrow band detection." "LOWDOWN's uncritical acceptance of this dx report belittles the efforts of others to detect weak signals on the 1750 meter band under Part 15 rules. LOWDOWN's credibility is also damaged as a source of information on low frequency radio." *Editorial comment: I thank Dave for his letter, but respectfully disagree that our publishing of the news constituted uncritical acceptance. Nor do I agree that the circumstances which make the claim credible have gone unreported. Many members will remember the work of Max Carter, Mark Mallory, and several others, in pioneering BPSK modulation and reception techniques. Most of the early efforts were hardware-centered, and seemed intimidating to those who didn't have as much confidence in their construction skills as these hardy souls. Despite some dramatic demonstrations of beacon ID copy over hundreds of miles through noise levels that rendered CW signals completely unreadable, the field languished for a while, due to lack of a sufficient experimenter population. However, demodulation is a process that can be mathematically modelled, and therefore can be performed in software, which is more accessible to many people. This approach has been evangelized in these pages for the past few years by Bill de Carle, VE2IQ, first for Coherent CW and now for BPSK. (Coherent CW is well known by technically oriented members of the amateur community worldwide, and was also originally implemented solely in hardware. It is now more commonly sent and received with computers, using de Carle's same COHERENT package that's used for BPSK. There's also a German shareware variant of Bill's code in use among the CCW crowd, though COHERENT has since undergone further development and is now free to the end user.) Between Max Carter's "BPSK Bits" series, and Bill's articles on his COHERENT program, the bandwidth efficiency of these modes has been well documented in The LOWDOWN, and it did not seem necessary to recapitulate that point in the news item. Thus my contention that a basis for these DX claims has been established. Experiments continue among a greater number of experimenters at more locations than ever before. Considering that conventional CW QSOs have been confirmed over several hundred mile distances, and there are credible recordings of rare California-Hawaii beacon reception, one would expect that the theoretical advantages of BPSK and related modes are borne out in practice from time to time, too. Whose project is it? Actually, it's quite a few people's individual and joint projects. The C/HDO beacon was created by Cliff Buttschardt, a licensed amateur operator, retired merchant marine radio operator, and instructor at Cuesta College. It is my understanding that students carry out projects and experiments there, too. But HDO is not the only beacon transmitting BPSK regularly...there's also MAX in Wyoming, and BPSK has been transmitted on the amateur bands as well. The software came from Quebec. At least one of the receivers mentioned in the news item came from John West in Colorado, but another was Lyle Koehler's commercial ICOM HF transceiver. Longwave experimenters from such varied locations as Hawaii, Arizona, and Virginia have also been listening, as well as numerous hams, now that transmissions take place on their bands. In addition, informal consultants on the project include such longwave notables as Jim Ericson and Frank Cathell, and experts from the amateur community and military research institutions (the latter not in their official capacity, I presume). There is a veritable flurry of e-mail between these folks every week, of which I am privileged to get a skimming. If there were reservations in any of their minds, I have no doubt they'd contact us directly. CCW and BPSK are also discussed among hams worldwide via the Internet, as part of news groups on digital signal processing. As for specific technical issues associated with the reception reports, some of these have been addressed before. The timing of reception was based on lowest noise levels and least broadcast interference at the receiving QTH. It was not known (and may remain a mystery for some time) whether there were specific propagation effects at play. I doubt it. In solar- terrestrial terms, it was a quiet winter. More than that would be hard to say until many more reports are in. Undoubtedly, the received signal levels were quite weak. Their relation to thermal noise would depend on the noise bandwidth being considered, however, and it should be clear that we are talking about very minimal bandwidths in conjunction with these modes...less than the ear/ brain system, for all its wonderful capabilities, is able to manage on its own. In addition, the "frame grabbing" that has been mentioned in some of these reports is useful when one knows that a certain limited amount of information is being repeated over and over. In one sense, it is a way of integrating the received signal through several repetitions, thus increasing the effective signal and averaging out some of the noise. In terms of information theory, it's another way of reducing bandwidth. (If it takes longer to be certain of the received signal, it's the same as if the data rate...and, effectively, bandwidth...has been reduced.) It may be true that random messages would be more convincing. But I can assure you that neither I, nor other, more skilled programmers who have seen the COHERENT program, have found any indication that the HDO identifier is embedded anywhere in the receiving software. Until it was demonstrated that call signs could be received, there was little point in trying longer messages. That could be in the works, though, according to what Cliff said in last month's column. Now...up to this point, most everything I've said is basically a rehash of material that has appeared in The LOWDOWN during the last three years. Newer readers may not have encountered some of the material before, though, so it's worth repeating. One point Dave mentioned *hasn't* been covered before, and that is the efficiency of the transmitting antenna. However, Cliff had already written about that for his report this month, so I'll just leave his remarks as the authoritative source. The LOWDOWN does not have a peer review procedure like scientific journals. But, like scientists, we have a self-correcting tendency. Any number of questionable ideas have appeared here over the years. They have been critiqued in print. And sometimes the critics have been pummelled thoroughly too. Eventually, tranquility is restored, and the soundest ideas live on. For that reason, even if the reported DX were not true, I would not fear that it detracts from the efforts of other experimenters in the long run. But I also want to assure Dave, and all our readers, that this DX report was not given credence lightly. It would not have been so readily accepted, had it not come from such a widely scattered group of experimenters, with long-established reputations in the field, using a wide range of equipment. It would not have been given such credence if the project were a one-shot deal, or if unnecessary obstacles were being placed in the path of anyone who wanted to participate, or if only a handful of people inside the organization (and nobody outside) were aware of the project before. Quite the contrary, the digital fans have long encouraged the rest of us to get involved. For example... What follows is not a complete bibliography, just a few issues I could find at random with articles directly mentioning BPSK parameters, coverage tests, or both: Mar. '87 (*), Sept. '87, July '88, Nov. '88, May '89 (p. 17), Aug. '89, Feb. '90, Mar. '90, Apr. '90, May '90, June '90, Feb. '91, Mar. '91, Apr. '91 (p. 14**), May '92 (p. 15#), May '94, July '94, Sept. '94 (##), Dec. '94, Apr '95, May '95. My library is temporarily missing some back issues, notably in 1993 and 1995, where there are additional articles to be found. All articles above have BPSK in their titles, except those for which I put page numbers. Of special note: *Max Carter's initial definition of BPSK in The LOWDOWN, as near as I can determine. **Cliff Buttschardt's description of modes used at San Luis Obispo, when the beacon was still MPM. # First mention of frame grabbing. ## Description of COHERENT software and Max's experiments with below-noise reception. Now that it's easier than ever to participate, listener volunteers are being recruited for the on-going effort. The beacon keyer project last month may prompt a few more digital beacons next year, too. You don't find this sort of openness among charlatans, who already know their presumed feats can't be duplicated by others. For that reason, I think we are justified in lending faith to the record claim. Footnote. Enjoy whatever is left of spring time where you are. But don't let that summer correspondence fall off! Let us hear your news and views. 73. - - -