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Voyager 1 stops communicating with Earth

cnn.com

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Re: Voyager 1 stops communicating with Earth

#621
post #555

Earlier quoted context omitted.

I need an eink display on my office wall showing the current location/status. I always get a tremendous sense of wonder and wellbeing thinking about these probes/achievements, maybe it'd help keep me centered before the daily onslaught.

I think you could get away with just printing a status page once every few months.

Or moving a post-it note with a tiny little dot on it.

Re: Voyager 1 stops communicating with Earth

#622

Earlier quoted context omitted.

If the contents of your computer is anything like the contents of most old people's attics, there is a good chance your descendants really don't want to go through all of it. They'll just chuck it in the trash without even opening it. Turns out the next generation has their own life to worry about, and doesn't care much for their ancestors' stuff (unless it's money... they love money...).

But after enough time passes, lots of people do get interested in their ancestors. That's why DNA ancestry services are a big business - people get curious about where their unknown farther relatives came from. I guess there's just less mystery about people you actually knew.

[deleted]

Re: Voyager 1 stops communicating with Earth

#623
How sad to lose contact, but how wonderful that we seized our opportunity to send out this beautiful messenger into the great unknown.

This reminds me of something I have been curious about for some time now. The Voyager Golden record depicts the world at 1.5b years, 4.5b years, and 4.51b years. The image of the continents at 1.5b seems realistic with Pangea, 4.5b looks to be the world accurately today, but 4.51 is unrecognizable- with Oceania featuring many new islands, new islands around Madagascar, and a large gap between Northern Africa and Eurasia. What is this image? It’s especially confusing given that the earth is 4.54B years old and the ten million years time between the two images isn’t enough for any continental drift of that magnitude in any projections I’m aware of.

See Diagram 39 here: https://www.lost-painters.nl/atlas/

Re: Voyager 1 stops communicating with Earth

#624
post #585

Earlier quoted context omitted.

This is about error correction. The probes add a redundant convolutional code to their signal. Decoding this is easy as long as the error rate is low, a computer program can simply guess what bits have flipped. The issue becomes harder with a higher error rate, and a Viterbi decoder is computationally expensive, but can correct higher error rates than other constructions. Since the signal strength degrades with dista…

> a Viterbi decoder is computationally expensive, but can correct higher error rates than other constructions. Higher than others at the time, or higher than turbo codes or low-density parity checks?

What I read is that it is the best theoretically possible error correction mechanism, given a convolutional code as input, and thus also the highest cost mechanism that one would consider.

This doesn't mean that it is universally the best way of doing error correction, other ways of generating redundancy may provide a better set of tradeoffs.

Also, convolutional code is a system that can be configured in many ways, the complexity of the code generation feeds back into the decoding, so a simple convolutional code would be Viterbi decodable at the time, but a more complex system would overall provide better error correction, even though choosing such a system meant that Viterbi would be computationally infeasible.

Re: Voyager 1 stops communicating with Earth

#625
Hey, if there's any NASA folk here or if you can drop a line to them... I'm kind of MIFFED at the regularity with which this issue is reported in the press as a "repeating pattern of ones and zeroes" and no one it seems, has any desire to divulge the actual pattern that is being received.

If we're not in the Cold War surrounded by State Secrets, it is time to crowd-source this mystery and that means provide actual dumps of the repeating data along with examples of recent correct data... and perhaps a complete dump of instruction and data memory to the extent of which it is known... so armchair enthusiasts (who aren't all 'armchair' as some of them might have actually worked on Voyager or be familiar with its instruction set) can spot any real pattern or peg the origin of the repeated data. Of course the objective is to create a fault in emulation that at least partly mirrors reality, so we can devise strategies against it.

When I was a tech fixing S-100 bus memory cards and to a great extent today for some systems, identifying faulty chips from diagnostics or observed behavior was the same as fixing the problem, because they were in sockets and could easily be replaced. I even had a hilarious fault in memory-map days where spelling of a word processing document was flipping on the display (bit 1) but printed properly.

This sounds as if a conditional instruction has suffered a bit flip changing the condition and trapping it in a loop from which it should escape. The nature of the 'gibberish' (contemptible term in this context) might yield clues to the nature of the problem or to knowledgeable persons, where the data came from if it is a bit flip in a pointer. Whether crowd sourced persons are capable to actually solve the mystery or not, they might at least offer good suggestions for devising diagnostics to narrow down the cause.

We owe Voyager all our efforts, as the most inaccessible computer system in human history.

Re: Voyager 1 stops communicating with Earth

#626

Earlier quoted context omitted.

> even though there was no computer on Earth at the time fast enough to decode it I'm not sure what is meant by that. Not fast enough to decode in real time? There is/was no need to do that. The transmissions would have gone to tape in any case. Here is a link describing how to decode such a tape : https://destevez.net/2021/09/decoding-voyager-1/

TFA: >I will use a recording that was done back in 30 December 2015 with the Green Bank Telescope in the context of the Breakthrough Listen project. That recording was made in 2015 on a modern radio telescope, it is not from a tape. The GP has the details wrong though: when the Voyager design was finalized in the early 70s with the Viterbi encoder, there wasn’t enough computational power to decode the signal. By the…

I wrote test firmware for a very early spread spectrum transceiver that used something close to Viterbi encoding. It consumed 220mA in receive mode and 60-120mA in transmit mode. I was told some of that was the RF amps and ADC but a lot of it was the decoder.

Re: Voyager 1 stops communicating with Earth

#627

Earlier quoted context omitted.

I don't think the south American Brazilians are anywhere near as prudish as the central north American USofA denizens.

And I didn’t think South Crossers were never told what the A in USofA stands for but here we are.

Indeed, in a time when seemingly many basement Canadians struggle with Venn diagrams and naming a country that starts with the letter 'U'.

Re: Voyager 1 stops communicating with Earth

#628

Earlier quoted context omitted.

If the contents of your computer is anything like the contents of most old people's attics, there is a good chance your descendants really don't want to go through all of it. They'll just chuck it in the trash without even opening it. Turns out the next generation has their own life to worry about, and doesn't care much for their ancestors' stuff (unless it's money... they love money...).

Pretty much. Anecdotes about lives of elderly people are nice when you are sitting an evening with a glass of wine and plate of cheese. Otherwise who cares? Nothing is worse than trying to go through bunch of old faded photos where no one - even the owner - can identify who is actually in the picture. I guess in our day and age we could write extensive meta data about where and when a picture was taken and who is in…

My experience is completely different. I've painstakingly scanned my family's old pictures, transcribed the letters they wrote when on holiday, and still have some school crafts made by my grandparents.

After the death of one of my great uncles who died childless I picked up his photo and music collection. And I discovered the grandfather of a friend of mine in one of his holiday pictures, turns out they used to be friends and we had no idea.

Re: Voyager 1 stops communicating with Earth

#630
post #594

Earlier quoted context omitted.

It's really quite simple. The headline should tell us what happened. Voyager 1 is sending repeated data back to Earth. I think I saw an article on tech dirt saying the spacecraft was sending stuck in "groundhog's day" that I thought was clever

Is it repeated data? Or is it repeated gibberish? I thought they weren't able to interpret the data as anything.

It is repeated data from what I've read. It's the same contents of the data recorder over and over again.
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