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Free Clock Democratizes Atomic Accuracy

samzenpus posted more than 4 years ago | from the free-time dept.

IT 178

schliz writes "A new, trial network of software-based clocks could give data centers and networks the accuracy of an atomic clock for free. The so-called RADclock analyses information from multiple computers across the internet by collecting the time from each machine's internal quartz clock, the time it takes for this information to be transmitted across the network, and comparing all the information collected to determine a time that is most likely to be accurate, so machines are calibrated across the network with up to microsecond accuracy — as good as that provided by a $50,000 atomic clock, researchers say."

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How trustworthy... (1)

JustinRLynn (831164) | more than 4 years ago | (#32838208)

"The accuracy of an atomic clock" decided by basically a median, a robot committee?

Well, you do get what you pay for. Not that it won't be awesome, I just don't think it will find applications where such accuracy is actually needed.

Re:How trustworthy... (1)

jschen (1249578) | more than 4 years ago | (#32839562)

Seems to me that they'll get a bunch of precision, but not necessarily great accuracy.

Nano not micro (1)

nten (709128) | more than 4 years ago | (#32838210)

Real atomic clocks often have only have a nanosecond error. And new ones using ion gates are promising mobile clocks that are even more accurate. This is still pretty cool

Re:Nano not micro (1)

jgagnon (1663075) | more than 4 years ago | (#32838306)

What's a few nanoseconds among friends? :p

Computer Clock resolution? (1, Insightful)

JSBiff (87824) | more than 4 years ago | (#32838512)

What is the resolution of the built-in clock on most PCs? An Atomic clock might have nanoscale resolution, but if a computer's clock only has microsecond resolution, then it stands to reason that you can only synch the computer to within 1 microsecond of accuracy, no?

Re:Computer Clock resolution? (4, Informative)

mysidia (191772) | more than 4 years ago | (#32838842)

That's right. Also, PC clocks tend to be not that great, in terms of reliability of the frequency, and error such as clock drift.

Hence the general recommendation to use NTP to keep your clock in synch with a good time source; a good time source, being something such as an atomic clock, or a radio-based receiver that provides time from a good source.

A PC clock can easily have errors of 100 PPM or higher. Or ~10 seconds of drift per day

Factors that seem small such as temperature can effect the frequency of the clock crystal also

Re:Computer Clock resolution? (5, Interesting)

vlm (69642) | more than 4 years ago | (#32839154)

if a computer's clock only has microsecond resolution, then it stands to reason that you can only synch the computer to within 1 microsecond of accuracy, no?

No. You can sync up to fractions of a clock cycle fairly easily. On average you can only report the time at any instant with around 0.5 uS accuracy, but you can set the edge where it cuts over from one uS to the next as accurately as you want, given enough time to sync...

Slashdot car analogy is I change my oil 4 times a year, so you're saying I can't tell you when I change my oil with any accuracy higher than a whopping 3 months. Yet I assure you, if sufficiently motivated, I can "sync up" such that I change the oil precisely at midnight on the 1st of every third month, with a reportable accuracy of like an hour or so.

Re:Computer Clock resolution? (0)

Anonymous Coward | more than 4 years ago | (#32839212)

I'm not sure I could ever be that motivated.

Re:Nano not micro (1, Interesting)

commodore64_love (1445365) | more than 4 years ago | (#32838588)

I don't think it's anything special.

If you want atomic clock accuracy, then you go fetch the time from an actual atomic clock. Even back in the 1980s, I had a Commodore Amiga program that would automagically dial a 1-800 number, fetch the time, and set my internal clock. Doing it today via the web should be a piece of cake.

Re:Nano not micro (4, Informative)

bunratty (545641) | more than 4 years ago | (#32838742)

NTP [wikipedia.org] has been around for decades. Even Windows phones home for the time every so often.

Re:Nano not micro (2, Informative)

jimicus (737525) | more than 4 years ago | (#32838806)

It's called NTP. You just have to be careful who you choose as your peers.

Re:Nano not micro (1)

Guspaz (556486) | more than 4 years ago | (#32839476)

ntpd also corrects for clock drift if the kernel supports it.

A solution in need of a problem? (5, Insightful)

iserlohn (49556) | more than 4 years ago | (#32838238)

NTP solved this ages ago by distributing atomic clock accuracy through the network.

The only problem this will solve is where it is a private network not connected to public NTP servers (or organizations that do not trust public NTP). In that case, they would most likely be able to afford a atomic clock.

Re:A solution in need of a problem? (2, Informative)

EricTheRed (5613) | more than 4 years ago | (#32838354)

NTP solved this ages ago by distributing atomic clock accuracy through the network.

The only problem this will solve is where it is a private network not connected to public NTP servers (or organizations that do not trust public NTP). In that case, they would most likely be able to afford a atomic clock.

An alternate would be radio clock signals like the old MSF Rugby signal in the UK (now moved to scotland)?

Ok not as accurate as an atomic clock but for most NTP cases it would be accurate enough

Re:A solution in need of a problem? (3, Informative)

marcansoft (727665) | more than 4 years ago | (#32838612)

GPS also provides an extremely accurate clock signal all around the world (after all, it comes from an atomic clock onboard the satellites). All you need is a GPS receiver. You can put most decent GPS modules into a "clock mode" where you lock their position on the globe and they optimize the calculations to give you the most accurate time.

Re:A solution in need of a problem? (2, Informative)

Kaboom13 (235759) | more than 4 years ago | (#32838878)

Meinberg makes a line of products that provide GPS backed NTP servers, as well as PCI/PCI-E cards that give PC's a GPS based clock (with an external antenna). They also make a pretty good NTP server/client for WIndows. It's overkill for most projects, but if you have a large datacenter or need for very accurate time, I would think they could be useful, if nothing else to keep you from having to rely on external time sources (which could be a potential security hole). This research seem more about making an improved and more accurate version of NTP, which is nice I guess, but NTP is already pretty accurate (on a scale of what is actually needed for 99.99% of situations).

Re:A solution in need of a problem? (0)

Anonymous Coward | more than 4 years ago | (#32838838)

An alternate would be radio clock signals like the old MSF Rugby signal in the UK (now moved to scotland)?

What, like GPS?

A side effect of GPS is that in addition to location, it gives you very very accurate time.

Re:A solution in need of a problem? (2, Informative)

Sub Zero 992 (947972) | more than 4 years ago | (#32838386)

From TFA:

"The RADclock project (formerly known under 'TSCclock') aims to provide a new system for network timing within two years. We are developing replacements for NTP clients and servers based on new principles, in particular the need to distinguish between difference clocks and absolute clocks. The term RADclock, 'Robust Absolute and Difference Clock', stems from this. The RADclock difference clock, for example, can measure RTTs to under a microsecond, even if connectively to the time server is lost for over a week! "

ymmv

Re:A solution in need of a problem? (1)

Idbar (1034346) | more than 4 years ago | (#32838746)

or example, can measure RTTs to under a microsecond, even if connectively to the time server is lost for over a week!

Let's see... with connectivity loss over a week, that makes around a 604800000000us RTT plus or minus some error. If you don't trust your clock, and it's important to you, why would you leave it without connectivity for over a week?

Re:A solution in need of a problem? (1)

vlm (69642) | more than 4 years ago | (#32839342)

Its gone thru a pretty severe journalist / PR filter.

"RTT under a microsecond" doesn't mean TCP RTT, it means the "delay" column on the equivalent of the peers command in the ntpq program for this new thing displays more than 3 decimals of milliseconds.

And the connectivity lost over a week means the "poll" interval column on the equivalent of the peers command in the ntpq program can go in excess of a week,

For example, I'm syncing to several clocks at home, one of which is ntp.sixxs.net. My delay is 130.768 mS and I'm polling every 128 seconds. All they mean is their monitoring system displays more decimal places on it's generic display, and polling intervals can be a wee bit higher.

I'm not sure as a debugging tool how useful it is to see more decimal places. Changing a printf format string for ntpq is probably simpler than implementing a new system.

How well a long polling interval will detect/correct for short term clock wander/errors is a mystery to me. Probably doesn't work too well. Or maybe the goal is, instead of syncing to small numbers of good clocks often, like stereotypical ntp, sync very occasionally to a huge number of clocks. Which you could do with ntp, although I suspect it would not work any better. Apparently the new guys disagree.

Re:A solution in need of a problem? (1)

Zephiris (788562) | more than 4 years ago | (#32839020)

It seems like this was already done in 1989 to ~25 millisecond accuracy. http://en.wikipedia.org/wiki/Berkeley_Algorithm [wikipedia.org]

So all they're doing here is attempting to refine it to http://en.wikipedia.org/wiki/Clock_synchronization before tryinig to come up with something better.

Re:A solution in need of a problem? (1)

Trivial Solutions (1724416) | more than 4 years ago | (#32838398)

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Re:A solution in need of a problem? (4, Insightful)

David Chappell (671429) | more than 4 years ago | (#32838572)

NTP solved this ages ago by distributing atomic clock accuracy through the network.

The only problem this will solve is where it is a private network not connected to public NTP servers (or organizations that do not trust public NTP). In that case, they would most likely be able to afford a atomic clock.

If one reads the explanation at the beginning of the article literally (as the person who wrote the summary did), the article does seem to say that this system averages the time from the cheap quartz crystal clocks in all of the computers in order to arrive at a highly accurate estimate of the true time of day. This of course is absurd. If all of the clocks start out between one and five minutes fast, they will converge on a time that is about three minutes fast. So much for microsecond accuracy!

The article suggests that NTP did indeed solve this problem. Reading between the lines I gather that these researchers are developing the next generation protocol to replace NTP. This will allow all of the nodes to synchronize more tightly with whatever time source (such as an atomic clock) is used.

Re:A solution in need of a problem? (4, Informative)

phoebe (196531) | more than 4 years ago | (#32838822)

The next generation protocol has already been invented too, the Precision Time Protocol [wikipedia.org] (PTP) recorded as IEEE 1588, with open source implementations [sourceforge.net] already available.

Re:A solution in need of a problem? (5, Informative)

Anonymous Coward | more than 4 years ago | (#32839648)

The next generation protocol has already been invented too, the Precision Time Protocol [wikipedia.org] (PTP) recorded as IEEE 1588, with open source implementations [sourceforge.net] already available.

PTP isn't a replacement to NTP: it's trying to solve a different problem. It's not useful on a general company LAN, but rather on a network that controls robotics or measurement devices.

Some limitations of PTP:
  * only one "grandmaster" clock, i.e., no redundancy
  * no WAN connectivity; it's UDP multicast-only, and so not very routable
  * no security/signing of timestamps; NTP has security extensions if you need to be able to trust the time
  * patented by HP/Agilent; NTP is both open and free

http://www.meinberg.de/download/docs/ieee1588/meinberg_ieee1588_conference2005_whitepaper.pdf

PTP was designed for small subnets of systems where measurement instruments and robotic systems are running on. This isn't a general PC/server solution.

Re:A solution in need of a problem? (1)

adosch (1397357) | more than 4 years ago | (#32838656)

I think you're missing the point, brilliance and usefulness of this. To put a rest to your argument, being behind a private network is just banter; you can still use a local time clock source from an internal server, server it up with NTP and let all your internal hosts connect to it to sync time. However, the point is that it's not a reliable time source, and even a network time nazi or your basic shell account user will tell you that the times are going to vary enough between your nodes to be bothersome from time to time.

I've been dabbling with GPS/PSS time sources with NTP for accurate timing for years and the biggest problem that RADclock solves is: the need for crazy expensive accurate timing devices, the time it takes to fine tune them and some crazy ass person (like myself) with a fetish for time keeping to stay on top of it. Instead of buying ridiculously expensive time keeping appliances (which most IT infrastructures do) we're back just being able to maintain very accurate time keeping with the server infrastructure you already maintain. And who gives two shits about 'what application warrants such an accurate clock', even remote server logging alone for log audits or troubleshooting should, alone, get your attention.

If this ever gets adopted widespread, this is just a big win for server time stability and keeping, in general.

Re:A solution in need of a problem? (2, Interesting)

EriktheGreen (660160) | more than 4 years ago | (#32838910)

Any IT organization still buying its own atomic clocks is probably a government operation. Seriously, GPS based local NTP servers have been out for years.

To answer your implication about time variation between nodes, even a basic ntp server to which your local network nodes sync will keep them in at the same wall clock time, even more so if you follow the protocol and use multiple servers, even if the time source is the servers' quartz clocks. If you have more than a few milliseconds skew after that, you've installed NTP wrong.

If you need more than fractional second timing for syncing a process or physical events, you don't try to coordinate timing over a communications medium without guaranteed latency (like ethernet). This can be seen in certain types of linux superclusters that abandon ethernet and its descendents in favor of synchronous communications.

It's great that these guys are developing a better way to estimate the correct time. I value this sort of thinking, if nothing else.

This sort of breakthrough deserves a web site announcement, or a scientific paper.

If I have to sort through the BS, sponsored articles, and overblown hype to find the useful info on Slashdot, why not skip the middleman and just browse the web itself?

Re:A solution in need of a problem? (1)

vlm (69642) | more than 4 years ago | (#32839430)

the need for crazy expensive accurate timing devices, the time it takes to fine tune them and some crazy ass person (like myself) with a fetish for time keeping to stay on top of it. Instead of buying ridiculously expensive time keeping appliances

Thats a heck of a lot of effort and money to get around opening port 123 on the firewall. Or implementing a "layer 7 firewall machine" that runs nothing but ntp, with one leg in the private net and one on the public internet.

Also in the olden days, like a decade or two ago, I was brought up that GPS units / radio clocks in general cost tens of thousands of dollars. Not so much anymore.

Re:A solution in need of a problem? (1, Interesting)

Anonymous Coward | more than 4 years ago | (#32838712)

RADclock aims to provide better accuracy than NTP.

TFA

Accuracy on the scale of 50 microseconds has been achieved for distances within 900 kilometres, and accuracy on the scale of 80 to 100 microseconds has been achieved within about 3,500 kilometres - the distance from Melbourne to Perth.

Wikipedia about NTP

NTPv4 can usually maintain time to within 10 milliseconds (1/100 s) over the public Internet, and can achieve accuracies of 200 microseconds (1/5000 s) or better in local area networks under ideal conditions.

Re:A solution in need of a problem? (1)

TheCarp (96830) | more than 4 years ago | (#32838790)

This really sounds to me like an interesting experiment in error correction.

You have n machines which were all (or most) at some point within 1 ms or so sync to an atomic clock. They all immediately started to add error to that time. So now, this system seems to be, sampling all of these machines, collecting all of their skew together. If the skew is random, you would expect it to cancel itself out. If it tends to bias in one direction, you should be able to figure out an average skew.

Then that average is used to set the machines, causing a sort of feedback loop, which makes me wonder if they are continuing to get NTP input at some nodes to try and add a signal for the feedback loop to tune itself into.

Kind of shooting from the hip but, its a neat idea anyway.

-Steve

Re:A solution in need of a problem? (1)

apharov (598871) | more than 4 years ago | (#32839438)

In addition to NTP, there's also IEEE 1588. All of these "clock synch over packet switched network" mechanisms are pretty similar, the differences are mainly in the timestamp filtering and processing. NTP details the algorithms, IEEE 1588 leaves them open to implementation and RADClock has its own algorithms (details unknown at least to me).

This story is also a bit dupeish, as RADClock has been recently featured here. Thus I'll copypaste the relevant parts from my previous reply:
--
(disclaimer: just finished my Master's thesis on a related subject) About the 1588 in general: its main selling point is the ability to do hardware timestamping (when using hardware with support!) of the two-way timing messages between master and slave. This eliminates the very significant timing jitter that happens in the software stack before the messages are timestamped. For reference, commercially available master-slave implementations using IEEE 1588 achieve synchronisation within tens of nanoseconds within LAN, and microseconds to tens of microseconds within WAN, depending on network conditions.

So overall I think that while RADclock might be ok as an alternative between NTP and IEEE 1588, it doesn't really bring anything new to the table. Some of the stuff in the Rideaux/Veitch paper has also been used with IEEE 1588 for quite some time, for instance the filtering for fast timing packets is a necessity for accurate synchronisation with IEEE 1588.
--

First post (0)

Anonymous Coward | more than 4 years ago | (#32838246)

With my super cool new software, i managed to get the first post!

Re:First post (0)

Pojut (1027544) | more than 4 years ago | (#32838308)

You might want to look into getting a refund...your "super cool new software" appears to be as worthless as not holding an iPhone the right way.

Re:First post (2, Funny)

Hognoxious (631665) | more than 4 years ago | (#32838632)

You might want to look into getting a refund

That reminds me, just where exactly did you get that sarcasm detector?

Re:First post (1)

Rockoon (1252108) | more than 4 years ago | (#32839144)

The iDetector is available now at your nearest Apple Store. Make sure you get the carrying case.

Re:First post (0)

Anonymous Coward | more than 4 years ago | (#32839692)

A refund? But it was free.

Damn Slashdot, i know we don't read the articles much, but the title?!

Re:First post (1)

somersault (912633) | more than 4 years ago | (#32838370)

I think you've been had.

Most probable time... (5, Funny)

mrt_2394871 (1174545) | more than 4 years ago | (#32838250)

I can imagine the speaking clock:

"At the third stroke, it will be, most likely, sixish"

Use GPS (2, Insightful)

maroberts (15852) | more than 4 years ago | (#32838260)

They have atomic clocks on board and GPS receivers therefore give highly accurate time.

Re:Use GPS (0)

Anonymous Coward | more than 4 years ago | (#32838338)

Most datacenters don't get good GPS reception :D

Re:Use GPS (1, Insightful)

Anonymous Coward | more than 4 years ago | (#32838430)

But their rooftops do.

Re:Use GPS (1)

Thundersnatch (671481) | more than 4 years ago | (#32838870)

Good luck getting a GPS receiver on the roof of an existing facility. Running conduit, grounding, waterproofing, etc. People say "hey, the Garmin GPS 18x costs only $100", but it will require ten months and $5K to install.

Re:Use GPS (1)

frinkster (149158) | more than 4 years ago | (#32839362)

Good luck getting a GPS receiver on the roof of an existing facility. Running conduit, grounding, waterproofing, etc. People say "hey, the Garmin GPS 18x costs only $100", but it will require ten months and $5K to install.

If you wanted to mount a GPS receiver on the roof of a building and wanted to use something off the shelf, perhaps you would be better off looking at the Garmin marine offerings. The GPS 17x has the same timing accuracy of the 18x, has the same MSRP, yet is packaged in a weatherproof housing designed to be mounted on a boat or a pole and survive the harsh conditions of the open ocean for many years.

...30ns accuracy from GPS (1)

maroberts (15852) | more than 4 years ago | (#32838356)

A long time ago (15 years!) I worked on the predecessor to http://www.symmetricom.com/products/gps-solutions/gps-time-frequency-receivers/XL-GPS/ [symmetricom.com] . I'm sure the modern day equivalent here doesn't cost 50k and will give you a local accurate time signal.

Re:...30ns accuracy from GPS (0)

Anonymous Coward | more than 4 years ago | (#32839196)

I have a couple of cheap Trimble modules given for 15ns jitter. Using both should reduce and smooth the jitter even more...

Re:Use GPS (1)

vrillusions (794844) | more than 4 years ago | (#32838424)

I have a gps receiver at home (the infamous Garmin GPS 18 LVC) and my current offset is 0.000 msec with a jitter of 0.001 msec (so 1 microsecond). Actually I've hit the limit in linux at that point since last I checked linux can only resolve down to millisecond. BSD can go down to nanosecond. That GPS receiver cost a whopping US$90

Re:Use GPS (3, Interesting)

bickerdyke (670000) | more than 4 years ago | (#32838542)

A GPS receiver will be useless as the GPS time currently is (IIRC) 12 seconds ahaed of UTC.

GPS doesn't honor leap seconds. This behaviour is by design as it's quite hard to halt the sattelites orbits for a second.

Re:Use GPS (4, Informative)

Hognoxious (631665) | more than 4 years ago | (#32838600)

If it's off by a known amount, I'd expect you could calculate the real value with some kind of mathematical equation.

Re:Use GPS (2, Informative)

bickerdyke (670000) | more than 4 years ago | (#32838762)

- 12 seconds

The problem is that this will rise when the next leap second is scheduled. When GPS started, GPS Time was identical to UTC. And leap seconds aren't based on a regular pattern but on the irregulatories of earths movement.

So it's good enough for relative time or within a system that agreed to use GPS time instead of UTC. Any other setup would require constant manual intervention. (at least minitoring of International Earth Rotation and Reference Systems Services announcments)

http://en.wikipedia.org/wiki/Leap_second [wikipedia.org]

Re:Use GPS (2, Insightful)

gnieboer (1272482) | more than 4 years ago | (#32839160)

Yes, you could, but what about the next leap second that changes it to 13 seconds (or worse, 11).

If you wanted to keep your UTC accurate, you'd have to ensure you kept patching your software each time another was announced. Not the end of the universe by itself.

But then, you've also got to deal with the problem of overlapping time (1/1/2015 12:00:00.5 happening twice), which for most people isn't an issue, but if you've got an application for which microseconds are important (like the high-volume financial trading types mentioned elsewhere), then that could be an significant issue.

Re:Use GPS (2, Interesting)

arth1 (260657) | more than 4 years ago | (#32838622)

A GPS receiver will be useless as the GPS time currently is (IIRC) 12 seconds ahaed of UTC.

GPS doesn't honor leap seconds.

YRW, it's behind, not ahead.

And that's why you have /usr/share/zoneinfo/right hierarchy anyhow:

$ TZ=:America/New_York date; TZ=:right/America/New_York date
Thu Jul 8 09:14:01 EDT 2010
Thu Jul 8 09:13:37 EDT 2010

Re:Use GPS (1)

fuzzyfuzzyfungus (1223518) | more than 4 years ago | (#32838670)

Because leap seconds are not added predictably(the International Earth Rotation and Reference Systems Service does try to announce them with some notice; but the earth is pretty wobbly), that would be an issue for any system that has to spit out UTC for years or decades without any updates aside from GPS; but for pretty much any other system(and basically any internet or large internal network connected PC would qualify), who cares?

The GPS gives you a highly stable timebase for peanuts, and then you can correct to UTC in software; based on the current number of leap seconds in play.

Re:Use GPS (1)

EriktheGreen (660160) | more than 4 years ago | (#32838784)

GPS is fine because the reason to have time synced at different sites is to correlate events at those sites. As long as they're in sync, it doesn't generally matter if they are exactly correct with respect to the wall clock. If you need to compare event time to wall clock time, you do the math for the time period in question.

If you have some pathological need to have the exact wall clock time down to the microsecond (an amount of time no human can distinguish) correct and identical at multiple discrete locations, then it's true that GPS won't help you. But few things will.

Re:Use GPS (1)

Retric (704075) | more than 4 years ago | (#32839010)

While computers have significant issues with subtraction, I am positive someone can find a solution to this monumental problem. After all the algorithm, while clearly complex seems solvable if only networked computers could connect to some remote resource to discover new information occasionally. Or perhaps these computing devices could respond to some sort of human interaction to gather such information and respond in a well defined manor.

Re:Use GPS (1)

bickerdyke (670000) | more than 4 years ago | (#32839126)

While computers have significant issues with subtraction, I am positive someone can find a solution to this monumental problem. After all the algorithm, while clearly complex seems solvable if only networked computers could connect to some remote resource to discover new information occasionally.

Well.. it's called NTP.

Re:Use GPS (5, Informative)

AmigaAvenger (210519) | more than 4 years ago | (#32839012)

Might want to doublecheck your facts. GPS knows about the time difference, which isn't 12 seconds either btw, it is 19. The complete time message, which includes the correct amount, is broadcast every 12.5 minutes, so its possible that when you cold boot a gps, it will be off some amount of time before that is received. (12 seconds is common for lots of GPS engines, they have built in correct for the first 7 seconds of correction, but need the updated time message after connection to get the rest of the update)

Re:Use GPS (1)

bickerdyke (670000) | more than 4 years ago | (#32839098)

Yeah. I read it up a few minutes after posting...

i stand corrected.

leap seconds Re:Use GPS (1, Informative)

Anonymous Coward | more than 4 years ago | (#32839470)

Bleah.. you don't know much about GPS timing, do you?

The message that the GPS satellite sends *includes the offset from UTC* including the number of leapseconds.

  GPS time can't have leap seconds because it needs to be monotonic and continuous, like TAI time. UTC needs to line up with the Earth's rotation, so they need leap seconds.

Time arithmetic on GPS time is straightforward. Not so with UTC.

What about the other scientists? (1)

dimethylxanthine (946092) | more than 4 years ago | (#32838266)

Boy, that's going to leave a lot of nuclear scientists up in arms with a lot of unclaimed nuclear material on their hands.

Re:What about the other scientists? (2, Funny)

Yvan256 (722131) | more than 4 years ago | (#32838462)

You know what they say. When life gives you unclaimed nuclear material, you get busy creating superheroes.

Re:What about the other scientists? (1)

oldhack (1037484) | more than 4 years ago | (#32838924)

And practice saying this out loud:

MUAHAHAHAHAHAHAHAHAHAH!!!! HA. HA.

Stupid filter (no, not this bit).

Forgive my ignorance... (2, Insightful)

Pojut (1027544) | more than 4 years ago | (#32838268)

...but in what situation would the time of day on a server or cluster need to be accurate down to a microsecond? Military, I would presume...but what else?

Re:Forgive my ignorance... (0)

Anonymous Coward | more than 4 years ago | (#32838332)

High-frequency stock trading.

It solves one problem (4, Informative)

Schezar (249629) | more than 4 years ago | (#32838420)

The Financial Sector.

Also, synchronized robotics, precisely coordinated CNC, and a host of other applications. Primarily, it's where absolute time isn't the concern, but rather where arbitrary time must be consistent between multiple devices (accounting for propagation delays, failures, etc...). Of course, protocols like PTP solve this fairly neatly: this particular product solves a different problem, and probably isn't actually useful.

There are two time issues to consider. One is how close your environment is to true time. The other is how close your individual devices are to one another. Messaging time-critical information between devices is severely complicated when the two devices are not on the same plane time-wise. Atomic clocks and the like solve the first problem. PTP solves the second problem. NTP almost (95%) solves both, but falls short in certain extremely time-critical situations.

Re:It solves one problem (1)

Pojut (1027544) | more than 4 years ago | (#32838454)

Cool! Thanks for the mini-lesson :-)

Re:why accurate down to a microsecond? (1)

ibsteve2u (1184603) | more than 4 years ago | (#32838826)

Thinking the IRS and your local state and community tax collectors would like to know everybody whose e-return is >= 1 microsecond late. That penalty money is important to g'ment - particularly in these days when an industrial base decimated by inequitable free trade provides ever less tax revenue.

Re:Forgive my ignorance... (1)

camperdave (969942) | more than 4 years ago | (#32839502)

...but in what situation would the time of day on a server or cluster need to be accurate down to a microsecond? Military, I would presume...but what else?

... and yet would not be willing to use ntp or buy their own time base.

A new low in editorial savvy (2, Insightful)

EriktheGreen (660160) | more than 4 years ago | (#32838334)

So, someone's invented ntp_time? That's only been around collecting time from time servers, many of which are atomic clock connected, since about 1985.

I'm also pretty sure there are desktop clocks based on microcontrollers that implement ntp, so they display an accurate time without a computer.

Most data centers that really care about time nowadays install a commonly available GPS unit on site, which syncs clock time with all the atomic clocks in the flying GPS constellation.

Seriously, could the editor that greenlighted this have done a google search or something? It's getting embarrassing to read slashdot these days.

Re:A new low in editorial savvy (0, Flamebait)

Pojut (1027544) | more than 4 years ago | (#32838380)

Seriously, could the editor that greenlighted this have done a google search or something? It's getting embarrassing to read slashdot these days.

Well, the article WAS posted by samzenpus...even his "idle" stories tend to be a bit retarded*, so it should come as no surprise that one of his "real" stories is on the same level.

*By retarded, I mean fucking stupid, as opposed to charmingly funny with a learning disorder.

Re:A new low in editorial savvy (3, Informative)

the_olo (160789) | more than 4 years ago | (#32838532)

So, someone's invented ntp_time? That's only been around collecting time from time servers, many of which are atomic clock connected, since about 1985.

...

Seriously, could the editor that greenlighted this have done a google search or something?

Could you have done a google search yourself or something?

Then you might find this [unimelb.edu.au] :

The RADclock project (formerly known under 'TSCclock') aims to provide a new system for network timing within two years. We are developing replacements for NTP clients and servers based on new principles, in particular the need to distinguish between difference clocks and absolute clocks. The term RADclock, 'Robust Absolute and Difference Clock', stems from this. The RADclock difference clock, for example, can measure RTTs to under a microsecond, even if connectively to the time server is lost for over a week!

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32838646)

The summary is dreadful. It *should* be equivalent to the paragraph you quoted from the RADClock website...

The Editor stands accused, which ever way you look at it.

Re:A new low in editorial savvy (0, Troll)

EriktheGreen (660160) | more than 4 years ago | (#32838706)

So. What.

RTTs to under a microsecond! Whoa! That'll make.... absolutely no difference at all to me. As mentioned, if I care about exact time, I use a GPS receiver (two for redundancy).

If I don't care about exact time, then something accurate to within a second or so is just fine... ntp_time fits the bill. If I'm not comparing time sensitive records across sites, I don't even care if the clocks on a site are correct, only that they're in sync.

Yes, this is development of a new system for time. Good for them. It deserves an "attaboy" in an email message, not a story on slashdot.

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32838996)

Look, we found a new douche bag slashdot armchair critic poster child!

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32839094)

To be fair, the majority of the news you consume does not make a difference to you at all.

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32839480)

For true insight into how stupid EriktheGreen is, read his journal entry.

Re:A new low in editorial savvy (2, Funny)

CODiNE (27417) | more than 4 years ago | (#32839448)

The RADclock project (formerly known under 'TSCclock') aims to provide a new system for network timing within two years.

Damn 2 years?? I suspect the time is somewhere between 2009 and 2011...

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32838556)

RTFA: it's a better algorithm for syncing clocks over NTP.

Re:A new low in editorial savvy (2, Interesting)

thijsh (910751) | more than 4 years ago | (#32838604)

You missed the point... NTP is a mechanism to get time from an authority, and so is GPS (which probably uses a souped-up NTP-ish system to sync with ground control). This system is about being independent from authoritative servers. And there can be legitimate purposes why you might need it so it's a good thing they research it... Some of the reasons to want this might be:
- Reduce the potential points of failure from one single bottleneck to infinite peers.
- Require no configuration (some old routers for example have a wrong time and log full of errors because the NTP server preprogrammed is gone).
- Protect against sabotaged NTP servers (in case of attack, or deliberate government intervention).
- Maintain high resolution timers in sync when the internet kill switch is tripped (or any internet-disrupting calamity).
- You're on Mars, and forgot to bring an atomic clock with you on the first colony ship...
- You're just paranoid about anything the government says, even the time...

Also this mechanism adds something new: Accurate time difference between two events (something that can still be very skewed with NTP when you have in inaccurate crystal).

All in all interesting, and worthy of a Slashdot dupe... :)

Re:A new low in editorial savvy (1)

EriktheGreen (660160) | more than 4 years ago | (#32838668)

Nah. Apart from the last two, all these items are addressed by the GPS receivers. Companies with dire needs for accurate time can use two, they never go down when the network is down, they can work in a mobile environment, multiple corporate sites can be assured of having synced time regardless of network delays.... I'm all for the development of new algorithms and code, but this is about as interesting as an update to the Windows clock program.

Re:A new low in editorial savvy (1)

thijsh (910751) | more than 4 years ago | (#32838830)

What makes you think the US won't sabotage GPS when they need to? Especially since weapons and troops now use GPS frequently to find targets they can easily send faulty data to mess with the enemies equipment... This is not really all that far fetched in a war scenario! Also an internet kill switch could easily encompass GPS... If you need accuracy no matter what (even in the case of a war, and in isolation of the rest of the world) GPS does not help.

But even the outside scenario of a time synchronizing system on Mars can be enough reason... When spaceflight becomes more common and they run into problems with time dilation etc. it's a good thing to be able to resolve the local time anywhere with anyone.

Re:A new low in editorial savvy (2)

EriktheGreen (660160) | more than 4 years ago | (#32838974)

So let me get this straight... you're stating that the reason this should be a Slashdot story is because A) The US government may sabotage GPS, and in such a situation our first concern would be accurate time on our computers and B) When we go to mars and/or have problems with time dilation due to near lightspeed travel, we'll need the ability to sync local time over a variable latency network because atomic clocks will still be too expensive?

I'm gonna go out on a limb and say this is not a big deal.

Re:A new low in editorial savvy (1)

thijsh (910751) | more than 4 years ago | (#32839364)

I'm saying if they found an interesting way to both improve NTP with time difference *and* make it work stand-alone independent from central servers that's called a technological improvement. You might not see the merit right now, but that's not the point... It's legitimate news for nerds! Come on, admit it, half the shit we love has absolutely no link to the real world whatsoever... :)

Re:A new low in editorial savvy (0)

Anonymous Coward | more than 4 years ago | (#32838698)

I thought the exercise was to measure time using only equipment that you own. Assume that you're the military in a rogue state and you don't trust NTP or GPS.

Uhmmmm (1)

rotide (1015173) | more than 4 years ago | (#32838378)

Say I have 1000 PC's at my place of work and a certain percentage are usually a little fast (clock wise) while another percentage are usually a little slow.

If I use the average of all clocks to determine the "actual" time, wouldn't it slowly shift either to the slow side, or the fast side over time?

Say 550 of those 1000 are usually a second slow per day. That is a bias towards slow every time we take an average. We sync all clocks to the slow side and keep on repeating this. The longer you do this, the worse your accuracy is.

NTP works because we basically call one clock (or set of clocks that are synchronized) correct and we sync to those. If a correction to the master is needed, we will all correct at next sync.

Then again, for mental masturbation, how can you ever tell that one clock is right, versus another. Take two teams, put one on one side of the world and another team on the other. Give them a billion dollars each to develop the most precise clock in the world. When they are finished, compare the times on both. Which is correct? Especially considering time dilation, etc. I'll stop now since I've digressed considerably.

Re:Uhmmmm (5, Funny)

whyde (123448) | more than 4 years ago | (#32838534)

This reminds me of an old joke about a retired Admiral who is responsible for sounding the morning cannon at the naval base, walking past a watchmaker's shop every morning and setting his pocketwatch to the correct time from a reliable old grandfather clock in the store window.

One day, on the walk in, he happens to see the watchmaker cleaning the store windows and mentions how he finds it amazing that the old grandfather clock keeps such flawless time.

"Oh, that old thing?" says the watchmaker. "It drifts horribly, and I have to reset it almost daily."

The Admiral then asks, "Since I've always noticed that it's reliable, from where do you get the time to set it?"

The watchmaker replied, "I use the report from the morning cannon at the naval base. It's always right on time."

Favorite Quote (3, Funny)

B5_geek (638928) | more than 4 years ago | (#32838456)

One of my favorite quotes relates to this;

Credit goes to Mark Twain (IIRC).

"When you have a watch/clock you always know what time it is. When you have 2 you are never quite sure."

Re:Favorite Quote (2, Interesting)

he who meows (766234) | more than 4 years ago | (#32838748)

But a man with three clocks is more sure than a man with two.

Re:Favorite Quote (1)

tokul (682258) | more than 4 years ago | (#32839352)

Credit goes to Mark Twain (IIRC).

He was a writer and not mathematician. I suspect that he never thought that having 10K+ clocks and being able to calculate average will make a difference.

Although I would not call this clock thing a replacement for atomic clock. It does not show atomic time. It shows statistical time average. It might be most accurate atomic clock only when sources use atomic clocks.

The idea sounds good on paper (1)

Yvan256 (722131) | more than 4 years ago | (#32838486)

Can't wait to see all computers set their clocks to January 1st, 1980.

Segal's Law (1)

bittmann (118697) | more than 4 years ago | (#32838498)

"A man with a watch knows what time it is. A man with two watches is never sure." -- Segal's Law.

At last (1)

clickclickdrone (964164) | more than 4 years ago | (#32838602)

Something that can measure my sexual stamina properly ;-)

Re:At last (0)

Anonymous Coward | more than 4 years ago | (#32838802)

You get sex? REAL sex? You have much to teach us....

GPS disciplined OCXO (0)

Anonymous Coward | more than 4 years ago | (#32838682)

What is the purpose of knowing time that accurately? You often want a clock signal that's that accurate, that's much more useful.
You can get 10MHz OCXO modules with a GPS receiver that syncs the OCXO to the satellites' on-board atomic clocks.
Much better.

it doesn't work that way (1)

Lazareth (1756336) | more than 4 years ago | (#32838738)

So adding together a bunch of imprecise measurements together and getting the median gives you greater precision? No. Well, it might, maybe, but you won't know. depending on the statistical variance and how it is spread. But you won't know it is precise, you can only say how likely you are to be precise. that's not the same thing. Also, as I read it it collects and judges upon the time, whereafter it sets all the clocks to the median? Exactly how does this counteract drift? How long does it wait between updates? For how long does it collect samples? What they're doing is that they're collecting a number of samples, hoping that their variance is spread evenly, thus the median must be the precise time. Fun fact: that only increase the precision (and quite a bit!) if you collect an near-infinite amount of samples. I really do doubt they have a near-infinite amount of computer clocks.

Re:it doesn't work that way (1)

Lazareth (1756336) | more than 4 years ago | (#32839002)

oh and only if the variance is a neatly bell-curve-shaped or otherwise have a high rise at the median. Otherwise you're completely fubared if your +-5 microsecond clocks have a bias for +2.

This reminds me of the Swiss watchmaker (1)

ribuck (943217) | more than 4 years ago | (#32838782)

This reminds me of the old Swiss watchmaker. Every day at noon, regular as clockwork, on office worker walked past the watchmaker's window on his way to lunch. This was the watchmaker's reminder to carry out his daily clock setting, so every time the office worker went past, the watchmaker checked that all of his clocks indicated noon.

One day the watchmaker happened to be out in the street at noon, and he mentioned this to the office worker. "That's funny", said the worker, "I always set my watch when I walk past your shop".

And so the network of software-based clocks will work fine, provided the computers from which the time is being aggregated are not themselves setting their time by this software-based clock.

Very useful for space applications (0)

Anonymous Coward | more than 4 years ago | (#32838848)

I think this piece of software might be useful for high speed (space) travel. Just read the theory of relativity, and you will know what I am talking about.

Like Real Estate Pricing Scheme (0)

Anonymous Coward | more than 4 years ago | (#32839366)

This sounds like real estate valuation scheme that led to the market crash. A Chinese mathematician said that you do not need to evaluate each property, just get an average of what the market says and you have your price. Then EVERYONE stopped doing proper evaluations and just looked at what EVERYONE else had for a price. If ALL the clocks switch to this, they ALL go off in some average direction.
Doing tests with 100 virtual machines does not show the effect. It must be with 1000 old computers to see it.

rogue/malicious clocks (1)

egburr (141740) | more than 4 years ago | (#32839522)

How does this account for rogue or malicious clocks present on the network? It sounds like it would be pretty easy to introduce significant error into the system.

I think I'll keep using one system connecting to the atomic clock and all the rest connecting to that one to keep their time accurate.

This is a simple case of NTP envy (1)

Terje Mathisen (128806) | more than 4 years ago | (#32839650)

The people behind this project tried to get the ntp hackers interested a year or two ago, but since the only thing they have is a possibly improved distributed algorithm, vs real NTP which has been designed to work even in the face of (intentional or accidental) falsetickers, nobody was very interested.

Any NTP wrangler who's the least interested in accurate local clocks will spend an hour and less than $100 to buy a cheap gps (Garmin GPS18(x) LVC) with Pulse Per Second (pps) output, a USB cable and a 9-pin RS232 connector:

Solder these together according to one of several howtos

(I can recommend http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm [satsignal.eu] , it is quite similar to my own rooftop clock which I've connected to a FreeBSD host in my attic.)

and you'll have a clock source which on average will be exact, with a jitter of a microsecond or two.

Terje
(who used to compile and host the windows ntp binaries for a number of years)

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