How can you trust the clock?
The train is using a week counter internally that overflowed. 17.11.2003 is exactly 1024 (2^(10)) weeks ago.
this post was submitted on 03 Jul 2023
198 points (95.0% liked)
Mildly Infuriating
35511 readers
781 users here now
Home to all things "Mildly Infuriating" Not infuriating, not enraging. Mildly Infuriating. All posts should reflect that.
I want my day mildly ruined, not completely ruined. Please remember to refrain from reposting old content. If you post a post from reddit it is good practice to include a link and credit the OP. I'm not about stealing content!
It's just good to get something in this website for casual viewing whilst refreshing original content is added overtime.
Rules:
1. Be Respectful
Refrain from using harmful language pertaining to a protected characteristic: e.g. race, gender, sexuality, disability or religion.
Refrain from being argumentative when responding or commenting to posts/replies. Personal attacks are not welcome here.
...
2. No Illegal Content
Content that violates the law. Any post/comment found to be in breach of common law will be removed and given to the authorities if required.
That means: -No promoting violence/threats against any individuals
-No CSA content or Revenge Porn
-No sharing private/personal information (Doxxing)
...
3. No Spam
Posting the same post, no matter the intent is against the rules.
-If you have posted content, please refrain from re-posting said content within this community.
-Do not spam posts with intent to harass, annoy, bully, advertise, scam or harm this community.
-No posting Scams/Advertisements/Phishing Links/IP Grabbers
-No Bots, Bots will be banned from the community.
...
4. No Porn/Explicit
Content
-Do not post explicit content. Lemmy.World is not the instance for NSFW content.
-Do not post Gore or Shock Content.
...
5. No Enciting Harassment,
Brigading, Doxxing or Witch Hunts
-Do not Brigade other Communities
-No calls to action against other communities/users within Lemmy or outside of Lemmy.
-No Witch Hunts against users/communities.
-No content that harasses members within or outside of the community.
...
6. NSFW should be behind NSFW tags.
-Content that is NSFW should be behind NSFW tags.
-Content that might be distressing should be kept behind NSFW tags.
...
7. Content should match the theme of this community.
-Content should be Mildly infuriating.
-At this time we permit content that is infuriating until an infuriating community is made available.
...
8. Reposting of Reddit content is permitted, try to credit the OC.
-Please consider crediting the OC when reposting content. A name of the user or a link to the original post is sufficient.
...
...
Also check out:
Partnered Communities:
Reach out to LillianVS for inclusion on the sidebar.
All communities included on the sidebar are to be made in compliance with the instance rules.
founded 1 year ago
MODERATORS
Damn you're good
Ever heard of the 2048 bug? If no i suggest taking a look at the wikipedia page. I think it is a fun read
2038! I develop embedded systems and we’ve been testing for this for years now. There’s also a similar 2036 GPS bug
You mean the Year 2038 problem?
yes... i feel dumb for that typo
But this would mean the epoch here would be the 2 April 1984 or maybe the 1st, if you respect the time as well, which sounds a tiny bit random lol. But so would be to use a week counter in the first place :D Especially since those trains are from the early 2000s.
EDIT: Other times in 2003 are also possible apparently https://twitter.com/TAltgeld/status/1646386165006716928?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1646386165006716928%7Ctwgr%5E99a8805bbdf28d116a3a7037dc24347da978e819%7Ctwcon%5Es1_c10&ref_url=https%3A%2F%2Fwww.kreiszeitung.de%2Flokales%2Fbremen%2Fsorgt-fuer-spott-im-netz-geniale-loesung-der-db-der-zug-aus-der-vergangenheit-92212981.html
How did you get to that epoch? I haven't seen any images of this happening earlier than 2003, so the overflow must have happened late last year or early this year, and whatever week 0 is is some time around 2002/2003. That would also fit with your comment that they were introduced in the early 2000s.
Maybe they just didn't expect the trains to last 20 years 😄
undefined> 20 y
Well, I did shown_date-1024 weeks=epoch. Your explanation sounds correct, though.
The only thing is, I've seen 2003 date before 2023 in random trains. Could also be a weird glitch when time sync fails or something.
It could be that the epoch is the start of 2003, so any train with a reset week counter shows 2003, and now they all do since the counter has overflowed late last year.
The fact that they use a week counter in general is something I remember from someone familiar with the onboard computer system, but I don't remember how it's set up specifically unfortunately.
Deutsche Bahn making up 20 years of delays in one go. Now that's efficiency
Did you hit 88 mph?
Don't think a German train can handle 1.21 gigawatts
Btw, thinking back to it, was that a nazi reference in that old movie?
Ah, Deutsche Bahn. Gotta love it.
Old public clocks sometimes use the mains frequency as a clock signal to maintain correct time. At the end of the day, the power authority is supposed to adjust the signal slightly to make sure these clocks maintain the correct time.
So I built a device that analyzes mains power supply phase variance with microsecond resolution. It's accurate enough that I can see the power authority turning on and off supplementary turbines to keeps the mains frequency correct.
That's how I determine my level of trust in public clocks.
Well, that and maintaining sub-relativistic velocities relative to them. Which is pretty easy honestly. If you're having problems with this, you've probably ceased to be biology or chemistry and started being physics. So you probably have more pressing concerns than keeping time!
Fellow vxjunkie, great to see on the other side
This is a train's clock, though. And since these displays also show additional information, I guess there's a bit more sophistication behind it.
Did you construct the analyzer yourself or can you buy that off shelf?
I built it myself. I used an optoisolator to convert the sine wave of AC power to a series of pulses, and also for safety reasons (it communicates data over light pulses, so that the mains power circuit is completely electrically isolated from the stuff I might touch). Then I used a microcontroller to precisely time the deviation from 50Hz, and output a serial port via MAX232. A desktop computer logs the data and gives me a real-time graph of the deviation. I might have some sample files lying around somewhere.
The microcontroller (ATMEGA16) ran at 20MHz using a crystal oscillator, and with some slightly funky tradeoffs, I was able to get a time resolution of 50 nanoseconds with an error of about 20 parts per million. If it deviates too far from 50Hz, I get nonsense measurements due to the tradeoff though (I trade measurement range for precision).
The original idea was to analyze tiny variations in phase at extremely short time scales to use the mains power transmission lines as a sort of large antenna array. Then use that to study space weather (e.g. solar wind, flares, etc.) more cheaply than sending up satellites. As a hardened skeptic, I originally built it as an elaborate practical joke due to all those 'Mayan Calendar Doomsday 2012' folks. You see if the world did end, I would have been in a position of absolutely dreadful embarrassment. So I built it as a sort of 'doomsday detector'.
Sadly, that component of the project never worked. I ran it during some solar activity peaks, and was unable to correlate the measurements taken by satellites to anything I found. It does still allow some weird things though, like I can apparently create a phase variance 'fingerprint' and use that to conclude whether a video was recorded in my city, and at what time. I've heard of some people doing that to youtube videos.
I can also get an idea of the power draw of the city I'm in. As people draw more power, the phase drops, then the power authority turns more turbines on. When the load lightens, the phase goes up, and I can see those turbines being turned off. This is sort of fun to turn on and watch if you get home early, you can see everyone else getting home and turning stuff on.
Learned that the hard way while stationed in Japan where their power is 50 Hz. The clock lost 10 minutes every hour.
I recall some of Japan being 60Hz, and the rest being 50Hz! That always struck me as pretty wild!
I live in SE Asia. You could say we lose 10 minutes every hour regardless of the timekeeping technology :P
Hooray, it's all been a bad drug induced dream! 18 year old me awakens in regional train.
Ah 2003, I remember it well.
I love German regional trains. This is a very common issue. Happens all the time.
wtf that's literally my birthday
That's a really old picture you got there ;)
God I would love it if I was suddenly transported back to 2003 as my current self.
As we have ultimately have set all of our private clocks with public ones as well, we always have to decide which public clock is more trustworthy in those moments. Except if you use a very precise sun dial.
walks into train, completely stoned. Sees clock. Panics. Ah fuck, I'm way too high to travel back in time... What if I fuck up the timeline?!
view more: next ›