11 ms·
First trans-Atlantic contact made on 432 MHz
- saagarjha 7y agoTo be fair, doing it from two islands way in the Atlantic is a bit of a stretch ;)
- jacquesm 7y agoOnly a little bit. This is quite incredible. I can imagine that doing it near population centers would be almost impossible.
- lucas_membrane 7y agoThe first transatlantic flight (Alcock and Brown) went from an island to an island. Lindbergh's famous New York to Paris flight left not from New York City (which is mostly on islands) but from Long Island.
- kwhitefoot 7y agoYes, but these islands are a lot further from the land on either side of the ocean. When you look at the map it looks less impressive than Alcock and Brown. But in fact this 432 MHz contact is over a greater distance, 3867 km, than Alcock and Brown's flight of 3040 km (https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock_and_Brown#Flight https://en.wikipedia.org/wiki/Transatlantic_flight_of_Alcock...) So calling it trans-Atlantic actually undersells it in comparison with other well known trans-Atlantic feats while at the same time setting people up to think the opposite.
- jacquesm 7y agoThat's super impressive even at 100W power at that frequency. Didn't even think that could be done at all. That antenna doesn't look like anything really special either, just an ordinary Yagi as far as I can see. Single reflector.
- klodolph 7y ago100W. Holy cow.
- turdnagel 7y agoI have lightbulbs that can do 200W!
- _wldu 7y agoI got from the USA (east coast) to Tasmania on less than 10 watts once, but not on 70cm.
- jacquesm 7y agoCW?
- _wldu 7y agoJT9
- lightlyused 7y agoI've done US east coast to Australia and New Zealand on 160m, with 5 watts and a vertical. Well, the vertical was 90' of tower and had 40,000 feet of wire underneath it and was feed with 1 5/8" hardline, but still.
- lightlyused 7y agoBTW, wasn't my station, but a friends I help with.
- heypete 7y agoI got from central Switzerland to Japan on about 10W on 20m once using JT65 or JT9 (I can't remember which). The antenna was a random length of wire tied a rock and tossed out of my fourth-story apartment window into a field below.
- CalChris 7y ago
- rjurney 7y agoWhat is the context here?
- jacquesm 7y agoVery long distance radio link with relatively modest power at a super high frequency. Normally you'd not get much better than line-of-sight with a setup like that. So you have to work DX using satellite or EME.
- acidburnNSA 7y agoThat last sentence means that if you want to contact distant stations, you have to connect through satellite relays or by bouncing radio signals from Earth to the Moon and back to Earth (EME)
- jhallenworld 7y agoIt helps that FT8 is amazing. I can easily contact Japan from Massachusetts using a modest "cobweb" antenna (on my side) and a large beam antenna (Japan side). 100 W, but this is on shortwave which can bounce off the ionosphere. WSJT-X is the software by Joe Taylor, who is a Nobel Laureate. The signal processing part of the program is written in Fortran.
- lightlyused 7y agoYea, ft8 is pretty cool. I've been able to work Europe on 6m during the summer E season (and hear Japan) along with some amazing dx contacts under marginal conditions on HF with it just using a simple dipole antenna.
- burfog 7y agoIt's an ultra high frequency. Super high frequencies are from 3 GHz to 30 GHz.
- BoorishBears 7y agoIs there a COTS radio set I could use for non-line of sight communication in the mountains?
- jacquesm 7y agoI think Inmarsat makes a nice little unit ;)
- vvanders 7y agohttps://elecraft.com/products/kx2-ssb-cw-data-80-10-m-transceiver https://elecraft.com/products/kx2-ssb-cw-data-80-10-m-transc... is the de-facto backpacking HF rig, usually the inreach[1] and similar are good enough for most people and doesn't require a license (just subscription). [1] https://explore.garmin.com/en-US/inreach/ https://explore.garmin.com/en-US/inreach/
- teraflop 7y agoAmateur radio equipment in the so-called HF band can get you non-line-of-sight transmission. You'll need a really big antenna, and you'll need to be content sharing a few hundred kHz of spectrum with everyone else on the same continent.
- jimhefferon 7y agoYou can have a lot of contacts with a pretty minimal wire antenna, such as a dipole.
- JshWright 7y ago"Big" doesn't necessarily mean "heavy" or "bulky" though. A decent length of lightweight wire and a tree can get you a very long way.
- blendo 7y agoIn the US, if you have a General class ham radio license, you could do it on the 7Mhz frequency if your antenna is relatively close (less than 1/4 wavelength) to the ground. See https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=2ahUKEwivkIrE79zoAhU0HjQIHUFnAYsQFjABegQIBBAB&url=http%3A%2F%2Fw4cae.com%2Fwp-content%2Fuploads%2F2016%2F10%2F40M-NVIS-Antenna-1.pdf&usg=AOvVaw1itMvyU5MVsdDqXpl-ye12 https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c... At higher frequencies (such as the 432 MHz used in this trans-Atlantic contact), the radio waves will not be reflected by the ionosphere and will disperse.
- ohazi 7y agoFT8 is part of a suite of digital transmission modes that are designed for weak signal / long distance communication. Often times these modes can be decoded even when the signal is below the noise floor. More details here: https://en.wikipedia.org/wiki/WSJT_(amateur_radio_software)#FT8 https://en.wikipedia.org/wiki/WSJT_(amateur_radio_software)#...
- haberman 7y agoIs there some technical innovation here enabling this, or had nobody ever tried it before? What are possible applications?
- jacquesm 7y agoI think those are very good questions. Technically, they seem to use pretty ordinary gear. The bit rate is super low, about 5 bps so you're not going to be sending over your movies any time soon. It's been tried but nobody ever succeeded and conditions would have be just so for this to work. Possible applications from a practical point of view not that I can see, though I'm sure that now that it has been shown to be possible there will be attempts to replicate it and from harder locations. But HAMs are known for doing things the hard way, after all, you could just pick up the phone and talk, that's not what this is about. It's about being able to do it, just like mountain climbing.
- ohazi 7y agoUHF is line-of-sight. The article speculates about a transient effect ("marine ducting") that allowed the signal to propagate further this time. It's not likely to be reliably repeatable. FT8 is ~10 bits/second (think of it as CW/morse code + better modulation + forward error correction).
- jacobmarble 7y ago- Weather happened to be favorable for a brief window of time - The FT-8 mode makes barely-possible communication possible
- wcfields 7y ago> Is there some technical innovation here enabling this I guess you could say the SDR based ICOM IC-9700 [1] transceiver FG8OJ used is enabling this by being reasonably priced [2] and off-the-shelf. It was released in January 2019 and has made experimentation of VHF/UHF more accessible. [1] https://www.icomamerica.com/en/products/amateur/hf/9700/default.aspx https://www.icomamerica.com/en/products/amateur/hf/9700/defa... [2] https://www.hamradio.com/detail.cfm?pid=H0-016656 https://www.hamradio.com/detail.cfm?pid=H0-016656
- teraflop 7y agoFor some context on why this is interesting: since the dawn of radio, we've known that relatively low radio frequencies (up to maybe 30MHz, depending on time of day, solar activity, and other factors) can propagate for very long distances, by following the earth's surface or bouncing off the ionosphere. This is why a portable shortwave radio can pick up radio stations from the other side of the world. Higher frequencies don't benefit from these effects, and generally don't propagate beyond direct line-of-sight. But in rare circumstances, atmospheric refraction can cause high-frequency radio signals to propagate much farther than normal, which is what seems to have happened here. On a technical level, this radio contact was made possible by the recently-developed FT8 digital modulation scheme, which is designed to transmit a minimal amount of data (basically just a pair of callsigns) at only a few bits per second, so as to make even extremely weak signals detectable. The "dB" column in the screenshot illustrates that the received signal strength was roughly 100 times weaker than the background noise.
- jiveturkey 7y agoFrom TFA: > The most likely mode of propagation was marine ducting with the signal being trapped close to the ocean. > There is a whole truckload of Sahara dust getting across the Atlantic this week. I blame it for the modification of the normal atmosphere into a superrefractive one, supporting communications for the first time on this band. Sahara dust dryes the air around it by absorbing moisture and thus modifying the refraction index. Like a G-Line feeder or an optical fiber, the difference in refraction index between different layers allows the propagation path to curve down following the Earth curvature to allow these fantastic QSOs. > I read about this phenomenon many years ago in an old ITU Bulletin justifying the enhanced superrefraction conditions usual between Cape Verde and the Western African Coast. > Jose, CO2JA From you: > this radio contact was made possible by the recently-developed FT8 digital modulation scheme My questions: 1. which factor was more important, or were they equal? 2. Is it COVID related? ie, atmospheric conditions are suddenly different around the world due to shutdown of industry.
- Normal_gaussian 7y agoIANA Radio Engineer 1. Both; perhaps the dust 2. No -- I've worked parallel to a whole bunch of radio obsessed electronic engineers; they get really excited about atmospheric conditions, and they regularly use weather maps to win competitions with unusually long transmission ranges (- a whole bunch of mad people across England / Europe / etc. go out on the same day and try and make as many contacts as possible. The team with the most unique contacts wins).
- aaron695 7y agoIs this tied to the lack of airplane flights?
- jacobmarble 7y agoNo.
- jacquesm 7y agoI would not be so categorical about that. 108 MHz is the low end of the VHF airband and 432 just so happens to be 4 times 108. So it may very well be that this connection would under normal circumstances be impossible due to interference.
- jacquesm 7y agoInteresting observation. Lots of radio traffic by aircraft might substantially raise the noise floor, even though they do not operate near that particular frequency one or more of their harmonics might interfere with signals that quiet. 432 is suspiciously close to 4 times 108 so you may be on to something there.
- wglb 7y agoUnlikely. For local communication, e.g., state to state, a common mode of attempts involve bouncing signals off of airplanes. But transatlantic using this method would be quite unlikely.
- bdavis__ 7y agoI see other comments that bring up the 'RF pollution' from aircraft travel..all of those airplanes spewing RF, and harmonics all over. How about normal pollution? All those tons of burned hydro carbon absent from the atmosphere (10K to 40K feet). Is it possible the non-normal chemical composition of the air is impacting the observed ducting? (de WB0VIX/5)
- DenisM 7y agoIn related non-news, it is possible to bounce signal off a meteor trail in the atmosphere. How cool is that? http://www.ccas.ws/radioastronomy.html http://www.ccas.ws/radioastronomy.html
- progre 7y agoAlso cool: Moon bounce https://en.m.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Earth_communication https://en.m.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93E...
- BenjiWiebe 7y agoAnd you can bounce signals off airplanes too, which I would love to do someday.
- helsinki 7y ago... but prop trading firms have been doing this for a long time.
- logicchains 7y agoA source to back this up: https://spectrum.ieee.org/tech-talk/telecom/wireless/wall-street-tries-shortwave-radio-to-make-highfrequency-trades-across-the-atlantic https://spectrum.ieee.org/tech-talk/telecom/wireless/wall-st...
- teraflop 7y ago"Shortwave radio" occupies the HF band, which has very different behavior from the UHF band discussed in this article. Amateur and commercial broadcasters have been using HF for transatlantic communications singe long before high-frequency trading existed.
- logicchains 7y agoMaybe this would have been a better response to the grandparent comment than downvoting it, as I don't think it's reasonable to expect most HN commenters to know the difference between UHF and HF (or even that they're different things), and the article makes no mention of it.
- wglb 7y agoThere are two interesting parts to this. First, the stratospheric ducting, which is quite rare, but can have dramatic propagation for 6 meters (50Mhz) and above. The second is the use of FT8, a new digital mode invented by Joe Taylor, W1JT, a nobel laureate. See https://en.wikipedia.org/wiki/Joseph_Hooton_Taylor_Jr https://en.wikipedia.org/wiki/Joseph_Hooton_Taylor_Jr. Of particular interest is how his research confirmed Einstein's theory about gravitaitional radiation From the web site, On VHF bands and higher, QSOs are possible (by EME and other propagation types) at signal levels 10 to 15 dB below those required for CW. The mode and other related modes are described here: https://physics.princeton.edu/pulsar/K1JT/wsjtx.html https://physics.princeton.edu/pulsar/K1JT/wsjtx.html. (Side note--Joe spoke at the Dayton Hamvention Contest Dinner a few years back, and brought some recordings of pulsars.)
- sneak 7y agoDoes the FCC reserve four digit call signs only for broadcast companies and nobel laureates or something? How does that work?
- kd0amg 7y agoThe amateur radio service has its own designated format for call signs: one or two letters, a single digit, then one to three letters. These days, the FCC normally issues a new licensee a "two by three" call sign (two-letter prefix, three-letter suffix), but depending on your license class, you can qualify for a shorter one. The Advanced and Amateur Extra license classes are allowed to have 1x2 or 2x1 call signs. According to the ARRL[1], there are currently 38093 Advanced licensees and 150793 Extra licensees (Advanced is no longer issued, but there are still quite a few Advanced who never upgraded to Extra). Of course, a call sign can only be held by one licensee at a time, and most (or all) of the 1x2 and 2x1 are assigned (I'm not sure on the current state of things with 1x3 and 2x2). So one only becomes available when the previous holder loses it (by license expiration or death). There are far more Advanced/Extra licensees than short call signs. There are also 1x1 call signs, but they are only issued on a temporary basis to special event stations (e.g., I have operated W8C, with a club whose normal call sign is W8YY). 1: http://www.arrl.org/fcc-license-counts http://www.arrl.org/fcc-license-counts
- geocrasher 7y agoSome more context: this was done on FT8 which is a digital mode designed to shine in weak signal work such as this. FT8 can decode signals as low as about -24DB. On HF, FT8 is used to go around the world. Even QRP (10W or less) a lot can be done. It's JUST for making a contact, there's no conversation to be had. The whole QSO took just a couple of minutes. It only needed to re-transmit one frame. Each frame takes 15 seconds. What's great is that since the QSO (conversation) is so fast, the conditions can be really variable and you can still make the contact. I'm not surprised it was first done with FT8. 73 de W7RLF
- taborj 7y agoMy longest QSO on FT8 is a touch over 5100 miles on 5w. That was pretty fun, especially since my little Bitx40 is feeding a Z dipole in the attic of my single story house. Definitely not optimal.
- geocrasher 7y agoA fellow bitx40 owner! Great to meet you. I love mine. I've hacked it to the Moon and back! They are great little radios. To bad the ubitx is such a turd.
- lightlyused 7y agoWhat don't you like about the ubitx?
- geocrasher 7y agoThere are a number of things. The first is the feature creep. It is designed to do CW, but it does it quite poorly. The first 2-3 characters are dropped when you send. Secondly, the new version has a fancy screen that at least upon release, was tremendously slow. Lastly, it took them several versions to get it harmonics down to levels that were legal in the US. Before that, tons of modifications were required. The design is solid, but the PCB layout is poor. The other thing is the PA. The layout is very poor. The higher the frequency, the lower the output. It's great at 30 meters and below, but 20 meters and up suffers. The BITX40 suffers from this too, but it's a single band radio and at 40m it works fine. I replaced the IRF510 with an RD15HVF1 and it worked great on 20M too. Mind you, this isn't an issue with the IRF510- it's an issue with board layout. The QRP Labs 10W PA uses two IRF510's in push/pull and can even work on 10m at full output. TL;DR: Over complicated, poor PCB layout, feature creep. That's not to say that Farhan isn't a nice fellow and a great ham- he definitely is! They just let this one out too soon before all the bugs were worked out, and allowed compromises that shouldn't have made it into production.
- angel_j 7y agoI was under the impression that we can propagate across the entire globe such healing vibrations.
- drmpeg 7y agoAlthough this is a wonderful accomplishment, it should be noted that tropospheric ducting happens every summer between the west coast of the US and Hawaii (at approximately the same distance of ~3800 km). The highest frequency contact was on 5760 MHz. Even I've made contact with Hawaii through the duct on 144 MHz from Silicon Valley (behind the Santa Cruz mountains). Signals are so strong, normal SSB voice can be used.
- jerome-jh 7y agoDoes this mean I can open my garage door over the Atlantic?
- gorgoiler 7y agoThis is inspiring. I’ve heard about things like FT8 and WSPR and have taken the first steps to get on track for a 10W license. Is it feasible to put together a simple transceiver to send short messages over 200km? I’d love to have an out of band way of staying in touch with my family that doesn’t rely on any one else’s infrastructure. The closest thing I’ve found are either RTL SDR hacks (receive only?) or the Elecraft kit ($900 for something way more Gucci than I think I deserve, given my amateur noob status!). For some reason I’m having trouble answering this question for myself, using internet searching!
- sizzzzlerz 7y agoTo be clear here, there is no such thing as an "10W" license. The FCC grants three types of licenses, each with increasing privileges. Any licensed person can operate at power levels up to 1500 watts for General and above, 200 watts for Novice/Technician. Operating at 10 Watts and below is a popular form of communicating called QRP. It does, however, still require a license. You also need to have a licensed individual at the far end if you want to have two-way communications. If they're receive-only, then no license is required.
- gorgoiler 7y agoOfCom licenses sound similar, but with the bottom rung license (“Foundation License”) requiring low power operation (max 1W to 10W) while you learn the ropes. Page 9 of IR2028 if you’re interested: https://www.ofcom.org.uk/__data/assets/pdf_file/0028/53965/ir2028.pdf https://www.ofcom.org.uk/__data/assets/pdf_file/0028/53965/i...
- th0ma5 7y agoI did US to Australia with a Raspberry Pi as the transmitter, a QRP labs filter for 10 Meters to clean up the signal, into an MFJ Tuner and then a random wire over the house and no other amplifiers. Like 100mw or less? WsprryPi essentially just turns the pin on an off really quickly to generate the signal. This was with an Amateur Extra license.