Have 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.
> 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.
A 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 :-)
Not 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.
I 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.
I 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.
Why 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.
They were referring to Dwingeloo [1] in the Netherlands, the telescope used in this article, not Arecibo. It stopped officially operating as a radio telescope in 2000, and has since been used for a variety of astronomy and amateur radio projects.
Because the object you are receiving a signal from is further, thus necessitating more sensitive receiving equipment that couldn't have existed in the past?
Superconducting detectors and materials science have obviously advanced leaps and bounds in the last 30 years: it's really not up for debate or a premise that can be "bought."
It made a big impression on me as a kid when visiting the telescope with my family. The exhibition outside taught me about Pluto's weird orbit and made me a Pluto fan.
I went there again with my own kids a couple of years ago and it was a bit disappointing. Not much to see. The solar system walk at the WSRT at Westerbork nearby is still cool.
I think it was deliberately built in a more remote area to avoid interference from other signals? When I was a kid (25 years ago :-)) I went on holiday in that area a few times, there were signs to tell people not to use radio equipment in the nature areas around the telescope.
It's cool that they kept it operational for amateurs and education.
> 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.
I 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? >_>
We 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.
The 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...
The "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.
Thank you for the clarification. Recently I've been reading a lot about tracking of space objects (though much closer ones, on LEO/MEO), so this is some very interesting stuff for me!
> 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.
Rad. 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!!
What I got is that SNR is relative to a time period. If you average the received signal over a longer period of time, the noise tends to cancel out but the signal tends to stack up (if the transmitter is still transmitting the same bit). Traditionally you'd use a narrower filter to remove more noise while keeping the signal, but today's (and last decade's and the decade's before that) fast computers can do part of the averaging in software, which leads to seeing a digital signal come in as noise, and then a signal magically appears after processing. This can also be done with CDMA signals provided that you're locked onto the timing of the code, which is something analog electronics can't do.
Ooo, 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?
If'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.
> If'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".
OK, but a giant parabolic dish is some parochial 20th century Earth tech.
I was imagining some little guys who create a 100 cubic AU grid of omnidirectional sensors, with a sensor every 1000km, all hooked up the mother of all DSPs. I can visualize that system identifying some pretty faint waves vibing in the noise. Am I wrong in thinking that this system could pickup AM radio really far away, easily... and once they got sick of that, even FM?
Each of the small detectors need to decern what is noise and what is not. They wouldn't know static from a station and having more clueless detectors wouldn't give you more any information in that regard.
An AU cubic grid of detectors would inform you where a signal originates from by comparing free space loss over the area of the coverage. IF you could discern a station from static.
> Each of the small detectors need to decern what is noise and what is not.
In my un-optimized imaginary system, the sensors are very sensitive and dumb, like me. All the difficult work is done by the central DSP-like brain that can identify even the tiniest of waves moving through the grid.
The utility comes from seeing the relative values in the grid... a pattern of tiny changes in some arc, moving through the grid.
Sure, killer triangulation (actually radial measurement?), but also possibly a decent 500 light-year AM tuner?
That's the game, more sensitive receivers receive more noise too. The game is sending something that will not look like the noise. The longer the sequence, the more likely to decode something but the slower the symbol rate (bandwidth)
Imagine your array popped out SHORT-SHORT-SHORT-LONG-LONG-LONG-SHORT-SHORT-SHORT
You just heard a morse code for SOS! The shorts where detected over 100Mhz (FM) +30db for 1 second each and the longs were 3 seconds each on a carrier that sites at +10db. That's amplitude modulation and that looks like intelligence but unless you knew morse code - it wouldn't make any sense.
The further away you get from the source, the more those decibel spikes weaken and will eventually be no different than the noise floor. Your super computer with a billion ears, only hears ~static~.
Try this, imagine instead if there was no free space loss in the electromagnetic field - we'd wouldn't be hearing humming but SCREAMS from all the noise sources from EVERYWHERE as if we were right next to them, forever. It would impossible to decern anything from anywhere. Communication is defined by its distance because signals have differing origins. Sensitivity, or lack there in, is a feature not a failure.
Who's to say a quasar isn't just a lovely time clock for signals encoded in the noise and we haven't figured out what the breakpoint from noise is yet?
> Who's to say a quasar isn't just a lovely time clock for signals encoded in the noise
Apart from a) quasars are broad-spectrum, not narrow frequencies (at least I assume that is the case), and b) the power required is too large for a civilization to realistically be able to generate. Not to mention that all that power is overkill for intragalactic communication.
In the spectrum plot you can see a signal, and you can see a noise floor that's below the signal. So.... Yes? Does it not? I'm well aware of negative SNR signals like GNSS, but this doesn't look like that.
It 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.
I'll have you know I learned typing in WP (word perfect) in the late 90's still.
(I guess they preferred typing on DOS based systems even though windows 98 was mainstream by then since it meant you couldn't alt-tab and lose focus or cheat somehow? IDK know. Maybe it was a licensing issue)
There'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.
An O appears to be a similar trigger. Our building manager persists in announcing the security tokens thus, as in, "Your new key FOB is ready.", and I feel real pain every time.
Mac 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).
Mac 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.
Same for Mensa. I've never seen an actual member write MENSA but people who fake being members do it constantly. Think it might come from some of the organization's various wordmark logos being misinterpreted.
> 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.
Pretty 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.
I'm more surprised that Russia or China haven't attempted to communicate with things like Voyager. Not necessarily to sabotage, but to find out as much as they can about it by interacting with it.
At the time? Perhaps, I don't know when the design documents* became public.
But today, Voyager 1 is a 50 year old curiosity, still of interest to cosmologists of course, but governments will be less interested in it than archeologists.
It'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
Yeah, 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.
https://destevez.net/2021/09/decoding-voyager-1/
> 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.
https://www.youtube.com/@balint256/search?query=arecibo
link that works on generic ytube clients like newpipe
Is there actually no back lobe on dishes that size? Or is it just extremely small?
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.
It is indeed incredible.
Nitpick, but I'm not sure 'satellite' is correct in this context. Voyager is in a solar system escape trajectory.
Arecibo failed to do so.
Decommissioned Announced November 19, 2020 Collapsed December 1, 2020
https://en.wikipedia.org/wiki/Arecibo_Telescope
[1]: https://en.wikipedia.org/wiki/Dwingeloo_Radio_Observatory
I went there again with my own kids a couple of years ago and it was a bit disappointing. Not much to see. The solar system walk at the WSRT at Westerbork nearby is still cool.
It's cool that they kept it operational for amateurs and education.
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.
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...
And that our solar system is more than a light day in diameter is also mind blowing.
Is there any info on this new antenna?
https://lightyear.fm
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.
OK, but a giant parabolic dish is some parochial 20th century Earth tech.
I was imagining some little guys who create a 100 cubic AU grid of omnidirectional sensors, with a sensor every 1000km, all hooked up the mother of all DSPs. I can visualize that system identifying some pretty faint waves vibing in the noise. Am I wrong in thinking that this system could pickup AM radio really far away, easily... and once they got sick of that, even FM?
An AU cubic grid of detectors would inform you where a signal originates from by comparing free space loss over the area of the coverage. IF you could discern a station from static.
In my un-optimized imaginary system, the sensors are very sensitive and dumb, like me. All the difficult work is done by the central DSP-like brain that can identify even the tiniest of waves moving through the grid.
The utility comes from seeing the relative values in the grid... a pattern of tiny changes in some arc, moving through the grid.
Sure, killer triangulation (actually radial measurement?), but also possibly a decent 500 light-year AM tuner?
Imagine your array popped out SHORT-SHORT-SHORT-LONG-LONG-LONG-SHORT-SHORT-SHORT
You just heard a morse code for SOS! The shorts where detected over 100Mhz (FM) +30db for 1 second each and the longs were 3 seconds each on a carrier that sites at +10db. That's amplitude modulation and that looks like intelligence but unless you knew morse code - it wouldn't make any sense.
The further away you get from the source, the more those decibel spikes weaken and will eventually be no different than the noise floor. Your super computer with a billion ears, only hears ~static~.
Try this, imagine instead if there was no free space loss in the electromagnetic field - we'd wouldn't be hearing humming but SCREAMS from all the noise sources from EVERYWHERE as if we were right next to them, forever. It would impossible to decern anything from anywhere. Communication is defined by its distance because signals have differing origins. Sensitivity, or lack there in, is a feature not a failure.
Who's to say a quasar isn't just a lovely time clock for signals encoded in the noise and we haven't figured out what the breakpoint from noise is yet?
Apart from a) quasars are broad-spectrum, not narrow frequencies (at least I assume that is the case), and b) the power required is too large for a civilization to realistically be able to generate. Not to mention that all that power is overkill for intragalactic communication.
But it’s a good sci-fi idea!
Had to reread that a few times to make sure
(I guess they preferred typing on DOS based systems even though windows 98 was mainstream by then since it meant you couldn't alt-tab and lose focus or cheat somehow? IDK know. Maybe it was a licensing issue)
https://en.wikipedia.org/wiki/List_of_forward_operating_base...
I wonder if this was included as a "please don't ask us if we're capable of hacking it, we are not" CYA.
https://x.com/nascom1/status/1851789221885022416
But it's still super easy to find them.
Usually it takes a few hours until the sat ham guys find them and post spectrums.
But today, Voyager 1 is a 50 year old curiosity, still of interest to cosmologists of course, but governments will be less interested in it than archeologists.
* e.g. https://voyager.gsfc.nasa.gov/Library/VOY_library.html and https://ntrs.nasa.gov/api/citations/19660011758/downloads/19...
Fully a third of the comments here are folks showing off their knowledge of non-acronyms.