9 ms·
Ham radio operators receive signals from Voyager 1 on Dwingeloo telescope
- LeoPanthera 2y agoA photo of the dish: https://en.wikipedia.org/wiki/Dwingeloo_Radio_Observatory#/media/File:Radiotelescoop_op_de_Heide_van_het_Dwingelderveld.jpg https://en.wikipedia.org/wiki/Dwingeloo_Radio_Observatory#/m...
- kstrauser 2y agoLovely! Those big dishes boggle my mind. For example, about Arecibo (https://en.wikipedia.org/wiki/Arecibo_Telescope https://en.wikipedia.org/wiki/Arecibo_Telescope): > The telescope had three radar transmitters, with effective isotropic radiated powers (EIRPs) of 22 TW (continuous) at 2380 MHz Twenty. Two. Terawatts. Now, what that means in context is that if you were looking down the business end of that dish, it would be hitting you with as much RF as though you were standing the same distance away from a 22 TW regular dipole antenna. Put another way, it shines with the same brightness at dead ahead as a 22 TW antenna would show from any direction perpendicular to its length. Because the dish is highly directional, it's only that bright in a tiny angle covering a tiny fraction of the sky. If you're standing behind it, nothing. In front of it? You turn into Dr. Manhattan. It's amazing.
- bobmcnamara 2y agoNear field effects have got to be huge on those things.
- slow_typist 2y agoA dipole does not radiate isotropically. It has a gain of 2.15 dB over the theoretical isotropic antenna. Gains with respect to the dipole are ERP, not EIRP. But still a lot of power :-)
- kstrauser 2y agoOops, you're right. That's still really freaking bright!
- 15155 2y agoI recommend watching the video series on YouTube re: the ISEE-3 Reboot Project before it's lost to history: https://www.youtube.com/@balint256/search?query=arecibo https://www.youtube.com/@balint256/search?query=arecibo
- 1oooqooq 2y agohttps://www.youtube.com/playlist?list=PLPmwwVknVIiUlPbkfBUY1ebP_8hA_4q8j https://www.youtube.com/playlist?list=PLPmwwVknVIiUlPbkfBUY1... link that works on generic ytube clients like newpipe
- viraptor 2y ago> If you're standing behind it, nothing Is there actually no back lobe on dishes that size? Or is it just extremely small?
- sbierwagen 2y agoNot zero. Even a full Faraday cage only has 90dB or so of attenuation. But measuring it would be darn hard, since the attenuated signal would be swamped by diffraction, skyscatter and reflection by nearby objects of the stronger side lobes.
- HPsquared 2y agoI wonder what the EIRP is of a typical laser pointer (or a high-powered one)
- pavel_lishin 2y ago> While we have shown that we can use the Dwingeloo telescope to receive the carrier signal from Voyager-1, we cannot use the telescope to communicate with it. NASA uses dishes in the Deep-Space Network (DSN) to communicate with Voyager 1. These dishes, located around the globe in Goldstone, Canberra and Madrid, are optimized for these higher frequencies and have a diameter of 70m, much larger than the 25m Dwingeloo Telescope. I wonder if this was included as a "please don't ask us if we're capable of hacking it, we are not" CYA.
- giantg2 2y agoYeah, it seemed a bit odd. Like I would wonder if I could xommjnicste with it. But I would also know that could jeopardize the craft and is probably illegal in some way.
- dylan604 2y agoIt's only a natural thought for people, if you can hear it, can you talk to it. So I don't see it as a CYA as much as just cutting off questions from people that know the intricacies of that kind of radio communication
- charles_f 2y agoPretty crazy to think that it's sitting like this in the open, with its old APIs all ready to be pentested. Secured by literal obscurity, introduced by a distance of a light day from the closest hacker.
- floren 2y ago"HAM" of course stands for "HAM - Acronym? Maybe!"
- nerdile 2y agoGlad to see someone else had the same reaction I did. There's no need to shout.
- dylan604 2y agogotta love those recursive names. Stallman would be proud
- immibis 2y agoI heard Stallman stands for Stallman's Toenails Are Likely Legitimate Methods of Acquiring Nutrition
- ForHackernews 2y agoI'm not a radio geek. Maybe @dang can edit the title? Fully a third of the comments here are folks showing off their knowledge of non-acronyms.
- lnauta 2y agoI got to visit the telescope earlier this year, its pretty cool. In a forest outside some small towns. For how well connected the Netherlands is, its pretty hard to reach. We looked at the sun and some planets in radio frequencies (its all radio astronomy with LOFAR nearby). That they can listen to Voyager with such an old instrument is incredible. It must help that the satellite is aimed at us.
- outworlder 2y ago> That they can listen to Voyager with such an old instrument is incredible. It must help that the satellite is aimed at us. It is indeed incredible. Nitpick, but I'm not sure 'satellite' is correct in this context. Voyager is in a solar system escape trajectory.
- lnauta 2y agoYou may be correct. In my head anything shot into space and still flying must be a satellite but that's a lazy shortcut.
- ChrisMarshallNY 2y agoThe term that I always hear, is "probe."
- Cthulhu_ 2y agoI wanted to joke that it's a solar sattelite but nope... Galactic center sattelite maybe?
- ggm 2y agoI think you'd have to demonstrate that the forces on its motion were dominated by motion relative to the galactic centre more than other effects, to get there.
- dylan604 2y agoWhy does its age come in to play? The think they are listening to is old too. The main thing is the size of the dish that allows for it, and then the skills of the operators to find the weak signal in the noise.
- Full_Clark 2y ago> NASA uses dishes in the Deep-Space Network (DSN) to communicate with Voyager 1. These dishes, located around the globe in Goldstone, Canberra and Madrid, are optimized for these higher frequencies Madrid Longitude: 4.3° W Goldstone Longitude: 116.9° W Canberra Longitude: 149.0° E 153.3° from Madrid to Canberra and only 94.1° from Canberra to Goldstone. Bit of a slight to Western Australia to skip over the ~120° option and put the third dish in Canberra.
- bobmcnamara 2y agoSome conspiracy theorists will tell you Goldstone is too close to Alice for that back then.
- brcmthrowaway 2y agoI think theres a CIA base in the desert right?
- parsimo2010 2y agoPerhaps the Aussies didn't want NASA to mess with their dishes at Geraldton. https://en.wikipedia.org/wiki/Australian_Defence_Satellite_Communications_Station https://en.wikipedia.org/wiki/Australian_Defence_Satellite_C...
- jen729w 2y agoThe Canberra dish is super easy to visit. Source: I live here, and have. :-)
- 2y ago
- Neywiny 2y agoI'm surprised they can still get a positive SNR at those distances. Incredible
- smitelli 2y agoI can’t find the article at the moment, but my recollection is that it has been estimated that each symbol was carried in on a few hundred photons.
- Neywiny 2y agoYeah I think I saw that on HN too. I'm just surprised they can see something on the spectrum.
- kstrauser 2y agoDoes it have? You can still decode a signal with negative SNR: https://heungno.net/?p=4373 https://heungno.net/?p=4373
- consumer451 2y agoOoo, sorry for the tangent, but this might be my chance to get a real answer for this. Can someone who really understands RF explain to me at what distance the concept behind this site breaks down, for a truly advanced technological species? https://lightyear.fm https://lightyear.fm
- dearing 2y agoIf's fun to think that our Sirius tech cousins at the BBQ under a Texas sized parabolic dish aimed at Austin would be jamming Nelly's "hot in here". Over distance its about fighting the noise in between the source and the receiver while also fading because of the free space loss, think of a flashlight - not a laser. So nelly volume ticks down while the local stations ramp up.. To keep your car jamming you'd build a growing antenna attached to your ford festiva that as you made your way would compensate for this loss by collecting more signal to focus back to a feed horn, a parabolic - like a larger magnifying glass focusing more ant burning heat in the winter versus the summer. Very roughly it seems it would be the size of Texas when you arrived at the BBQ, assuming you are traveling the speed of light and left in the early aughts. You wouldn't hear the song until you hit the break because its the frequency over time that pumps the jam.
- gaze 2y agoI know this is super nitpicky but Ham isn't an acronym. It's ham as in ham-fisted -- amateur radio.
- xattt 2y agoI always thought it was because OG hams had some sort of regional accent and would say hamateur.
- LeoPanthera 2y agoThere's something about three-letter words with an A in the middle that make people assume they're acronyms. HAM and MAC (as in, Macintosh) are often incorrectly written that way. It's weird.
- verandaguy 2y agoMac might be a word, but MAC, MAC, and MAC are all acronyms, to say nothing of the cosmetics brand MAC (styled as M•A•C, though not M.A.C., and remains a word, not an acronym or initialism).
- inopinatus 2y agoMac is a valid abbreviation of the Macintosh, which is named indirectly after John McIntosh, a Canadian farmer and apple breeder of Scottish descent, who gave his name to the McIntosh Red cultivar. Scottish artist Charles Rennie Mackintosh was also born McIntosh but revised his family name after a spelling error at the Glasgow School of Art. The Mackintosh that you wear is similarly misnamed after Charles Macintosh (no relation), inventor of the modern waterproof raincoat. And so it goes.
- quux 2y agoIf I'm understanding this right, they were able to receive the carrier, but didn't demodulate any signal or decode any data?
- amatecha 2y agoI wonder about that too, was it just only transmitting an unmodulated carrier at the time (minus 22 hours lol)? Or is the signal quality too poor to discern any modulation? Or something else? >_>
- thomas_tel 2y agoWe only see the carrier because it has such narrow bandwidth, the modulated data is for us not distinguishable from the noise. FYI, at this data rate the carrier contains 25% of the transmitted power.
- kqbx 2y agoThe article is light on details, but we can make some guesses based on the label "10s integrations, 1Hz channels" in the plot. I assume they have a bank of 1Hz filters, and they split the output of each filter into 10s intervals, and somehow combine ('integrate') each 10s chunk into a single number for each bin. They need to compensate the Doppler shift so that the signal stays in one bin over the 10s integration time. I imagine they are using non-coherent integration (basically computing total signal energy over 10s in each bin) to take into account that the doppler compensation is not perfect (if it was, you could have 0.1Hz bins with 10s integration time). If the above is true, then yeah, they can't demodulate any data because the integration time is much longer than symbol duration. I wonder if with more accurate Doppler prediction, you could get an ever longer integration time and narrower bins, and thus even bigger SNR gain, perhaps allowing signal detection with a smaller dish...
- thomas_tel 2y agoThe "live" plot (with the peak) uses indeed 1Hz bins (of 1 second), that we average over the last 2-3 minutes to reduce the noise. We could go even narrower, I might give that a try on the recorded data.
- ijidak 2y agoThe fact that Voyager is far enough for light to take a day to reach us is mind blowing to me. And that our solar system is more than a light day in diameter is also mind blowing.
- makmanalp 2y ago> almost 25 billion kilometers Had to reread that a few times to make sure
- amatecha 2y agoRad. I was pretty stoked when I received signals from Australia and New Zealand ~12000km away, and later from the International Space Station (actually technically much closer lol). I can't imagine how damn cool it would be to pick up anything at all from a freakin' deep space probe some 25billion km away!!
- slow_typist 2y agoIncredible achievement but would really appreciate if they laid out the details.
- teleforce 2y ago> Since the Dwingeloo telescope was designed for observing at lower frequencies than the 8.4GHz telemetry transmitted by Voyager 1, a new antenna had to be mounted. Is there any info on this new antenna?
- ElectRabbit 2y agoHave a look at Daniel Estevez blog. He's a regular user of bigger telescopes (like ATA) and managed to receive and decode Voyager 1. He wrote a GNURadio decoder for it. https://destevez.net/2021/09/decoding-voyager-1/ https://destevez.net/2021/09/decoding-voyager-1/
- xhkkffbf 2y agoIt would be nice if some HAM operators or other citizen scientists could provide some evidence about the US moon landing that can be verified independently. One friend won't shut up about it and it grows tiresome.
- HelloMcFly 2y agoHe wouldn't believe it anyway