Time.is
time.is
time.is
I keep finding all my physical atomic clock synced clocks (yes, I have more than one, they are cheap these days) disagreeing, sometimes by 2 seconds or more, which makes me laugh (great ideas ruined by poor implementation). I find many of the web sites (listed in comments or the original post) to also differ, perhaps for similar reasons of implementation choices.
I would presume all the sites work off various implementations of NTP, http://www.ntp.org/ plus some trusted source.
I guess my question is: has anyone found a site which is really, really accurate by reducing all the latency and lag, so what you see on the screen really is, to whatever precision, accurate? And would said person have access to a really good source for the comparison point? I don't seem to have one. Yes, I should have stopped at 3 so that I could pick the 2 closest ones (like the old saying: 1 clock is unsure, 2 clocks are worse, but 3 at least lets you make a decision)
I wonder, would you need to have NTP on the client side synced to a trusted source (say, in java, flash, or javascript) to get a good reading? Any server serving over HTTP induces lag, I would think, and NTP is supposed to account for transmission delays, or so I recall.
Thanks for sharing, another interesting time site to add to the collection.
That's why I laughed when Time.is tried to tell me that my clock was off by 1.8 seconds. Barring the sentence above, it just has no way of determining that.
Yeah, you're right. That's not so bad.
It just seemed like it was claiming a lot of precision that, from my own experience of javascript, browsers and network latency, seemed a bit over the top. (Granted, on the order of magnitude of seconds, I'll accept that. Less than 100 ms and I grow suspicious).
<removed NTP stuff>
I simply don't have any clocks that aren't part of electronic devices, my wristwatch being the exception (but it's analog (Roman numerals, even :P) and only has second accuracy anyway, so I don't fuss about it).
Simply put, all my devices take care of all this for me. My MacBook and Windows 7 work desktop are both configured to sync to the Apple NTP servers (lowest ping for me, AND they're always up. Microsoft's are down a good 10% of the time in my experience). My cell phone gets its signal from God knows where (iPhone 4S - it could technically be using one of 4 different sources) but is always more or less in sync with the rest (I just checked with time.is for what little that is worth, however, and while my MacBook says that my time is within the margin of error "The difference from Time.is was -0.007 seconds (±0.018 seconds).", my iPhone returns "Your clock is 0.5 seconds slow" - but I would trust my iPhone's NTP implementation over time.is' response as its the same OS X NTP that got it "right" on my MacBook) as it can theoretically use a) GPS b) GSM/CDMA towers c) NTP d) time from PC sync.
All my other electronic devices fall in the same category. Garmin nüvi (GPS), Kindle (NTP, auto configured), Cisco IP Phone (NTP, manually configured), Brother printer (NTP, manually configured). I purposely do not set my microwave clock because a) I'll never get it right, and b) any time the power cuts, it resets and in 2012 they're still too stupid to add a 5 cent battery to keep the time in case of power outage.
FYI: Ping is a remarkably bad tool to gauge the accuracy of remote time source. What is the delay value from "ntpq -p"
I highly doubt that Apple's time servers are your best bet for time synch. Use the pool.ntp.org servers, preferabbly with your country code: e.g. us.pool.ntp.org, ca.pool.ntp.org.
My ntpq -p output:
remote refid st t when poll reach delay offset jitter
==============================================================================
time.apple.com .INIT. 16 u - 512 0 0.000 0.000 0.000what happens if you change your time server to us.pool.ntp.org? (Substitute your country code for "us".)
Preferably you should have more than one server. The ntp reference implementation on osx is a little goofy because of the GUI configuration. But I think if you put us.pool.ntp.org,us.pool.ntp.org,us.pool.ntp.org for the server your computer will try to spin up three ntp connections. Atleast three, never two...
"A man with one watch knows what time it is; a man with two watches is never quite sure."
Close, but not quite; ntpd appears to be smart enough to realize you have three identical "server" lines in ntp.conf, and collapses them. Try this instead:
1.us.pool.ntp.org,2.us.pool.ntp.org,3.us.pool.ntp.org
Changing "us" to your country code, of course. Just tested, and it appears to produce the desired behavior.
Try editing /private/etc/ntp.conf and append:
# use multiple ntp servers
server us.pool.ntp.org iburst
server us.pool.ntp.org iburst
server us.pool.ntp.org iburst
Make sure you have an extra empty line above the comment. There is something goofy about the way osx includes the input from the graphical configuration and what is included in the /private/etc/ntp.conf In order to restart the service you need to disable/re-enable the automatically set time.My GPS + Pulse Per Second fed ntp server is remarkably better than a radio controlled clock. The Sure GPS evaluation board probably costs less than your radio controlled clock:)
dfc@ronin:~$ ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
oGPS_NMEA(0) .GPS. 0 l 12 16 377 0.000 0.001 0.001
bonehed.lcs.mit .CDMA. 1 u 32 64 377 51.365 0.670 0.364
rooster.stonybr .CDMA. 1 u 14 64 377 49.019 6.141 0.445
navobs1.oar.net .USNO. 1 u 1 64 377 57.310 9.494 0.456
meg.ee.lbl.gov .PPS. 1 u 1 64 377 88.639 -2.204 0.270
dfc@ronin:~$ ntptime
ntp_gettime() returns code 0 (OK)
time d3076554.79d48450 Sun, Mar 11 2012 13:54:28.475, (.475899416),
maximum error 234 us, estimated error 0 us, TAI offset 34
ntp_adjtime() returns code 0 (OK)
modes 0x0 (),
offset 0.856 us, frequency -32.941 ppm, interval 1 s,
maximum error 234 us, estimated error 0 us,
status 0x2001 (PLL,NANO),
time constant 4, precision 0.001 us, tolerance 500 ppm,
Radio clock reference material:NIST Page on Radio clocks: http://www.nist.gov/pml/div688/grp40/radioclocks.cfm
"How accurate is a radio controlled clock" http://tf.nist.gov/general/pdf/2429.pdf
"WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers and Consumers": http://tf.nist.gov/timefreq/general/pdf/2422.pdf.
Are you trolling or did you really miss the whole phrase "physical atomic clock synced clocks?"
https://en.wikipedia.org/wiki/Radio_clock#List_of_radio_time...
The Fort Collins signal is awful in the northeast. If you want to deal with the disadvantages of not using advanced computer algorithms to govern your clock i would recommend the USNO's phone service:
Time Voice Announcer, Washington, DC: 202-762-1401 & 202-762-1069 (DSN 762-1401, 762-1069)
Time Voice Announcer, Colorado Springs, CO: 719-567-6742 (DSN 560-6742)
On a related note, I always liked the British time announcements that used three tones, with the designated time being "at the third stroke". It's like a music conductor conducting a measure before you start playing or singing. I wonder if it's measurably more accurate than just playing a tone with the proper time is reached.
edit: A paper from 1989 on the subject: http://tycho.usno.navy.mil/ptti/1989/Vol%2021_14.pdf
You need time and frequency for "proper time."
time.is reports my clock is:
-0.004 seconds (±0.021 seconds).
I have a stratum one time source on the local network (gps+pps) and my ntptime agrees with the time.is estimation: dfc@bushido:~$ ntptime
ntp_gettime() returns code 0 (OK)
time d3077752.4160a634 Sun, Mar 11 2012 15:11:14.255, (.255381196),
maximum error 260579 us, estimated error 3294 us, TAI offset 34
ntp_adjtime() returns code 0 (OK)
modes 0x0 (),
offset -4842.630 us, frequency 8.446 ppm, interval 1 s,
maximum error 260579 us, estimated error 3294 us,
status 0x6001 (PLL,NANO,MODE),
time constant 10, precision 0.001 us, tolerance 500 ppm,
NB: this is my laptop. so powersaving, heat fluctuations are adding a decent amount of uncertainty from a metrological standpoint.Or maybe there is no such thing as "actual physical time" and there is only what people have agreed to call the standard. But in that case why do time sources, such as time.gov and time.windows.com, still give different times? I would think Microsoft would have fixed any bugs in their NTP implementation by now, so it's not that. If it's just politics about nobody wanting to move to someone else's time, then there's no way to tell which source is the real standard, so your most practical choice is to synchronize your clock to the times you deal with. That is, set your clock to your clock at work, or an average of your friends clocks, or whatever source they get their time from. I don't mind the existence of central time sources, because they are better than having to go out and find someone else's clock, but they shouldn't call themselves official if they aren't actually official.
So, does anybody know how the starting time for central time sources is chosen, and if any source is worthy of being called "the real time"?
ftp://ftp2.bipm.org/pub/tai/publication/cirt.290
Time is a really tricky and interesting topic. I would start with:
"From Sundials to Atomic Clocks: Understanding Time and Frequency"
http://www.nist.gov/timefreq/general/pdf/1796.pdf
"Originally published in 1977, this full-length book provides a comprehensive, easy-to-understand introduction to the field of time and frequency. Readers of nearly all ages and educational backgrounds should find it enjoyable. 306 pages."
Theoretically, you could measure the rotation of the earth and call that a day, but I have no idea how you would measure that down to the millisecond.
As to "Real Time", I don't know about the specific legalities, but the standard goes as follows: everyone uses UTC http://en.wikipedia.org/wiki/Coordinated_Universal_Time which is based off the International Atomic Time http://en.wikipedia.org/wiki/International_Atomic_Time
I too would be interested in how they picked the beginning epoch, i.e. "this moment right here is midnight from which all other seconds shall be referenced against" but in the grand scheme of things it doesn't matter - the only thing that matters is the standard we agreed to measure against.
This is not theoretical; this is known as sidereal time and is measured to the nanosecond...
Yeah. Nutation.
Nutation "…is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight…"
3550089600 35 # 1 Jul 2012 [1]ftp://ftp.iana.org/tz/data/leapseconds
http://en.wikipedia.org/wiki/Unix_time
"Unix time, (...) is (...) defined as the number of seconds elapsed since midnight Coordinated Universal Time (UTC) of Thursday, January 1, 1970 (...) not counting leap seconds"
Microsoft apparently rejected the idea of using leap seconds because Windows just isn't accurate enough:
The W32Time service uses the Network Time Protocol (NTP) in
Microsoft Windows Server 2003, in Windows Server 2003 R2,
in Windows Server 2008, and in Windows Server 2008 R2.
...
The W32Time service cannot reliably maintain sync time to
the range of 1 to 2 seconds. Such tolerances are outside
the design specification of the W32Time service.
http://support.microsoft.com/kb/939322Unix/Linux computers don't, Windows computers don't, GPS doesn't:
http://en.wikipedia.org/wiki/Global_Positioning_System#Timek...
GPS Time is designated as being coincident with UTC
(USNO) at the start date of January 6, 1980 (00 hours).
GPS Time does not count leap seconds, and therefore an
offset exists between UTC (USNO) and GPS Time (at this
date in April 2007: 14 seconds).
Unlike GPS, the GLONASS time scale is not continuous and
must be adjusted for periodic leap seconds. Leap seconds
are applied to all UTC time references as specified by
the International Earth Rotation and Reference System
Service (IERS). Leap seconds are used to keep UTC close
to mean solar time. Mean solar time, based on the spin of
the Earth on its axis, is not uniform and its rate is
gradually changing due to tidal friction and other
factors such as motions of the Earth's fluid core.
http://webone.novatel.ca/assets/Documents/Papers/GLONASSOver...This is the best overview I've seen of all the pros/cons with regard to UTC and whether leap seconds should be abolished:
http://www.agi.com/downloads/resources/user-resources/downlo...
Basically, much in the same way that we all despise DST (or date differences between Julian/Gregorian calendars), a certain part of me wants to know, if we humans last on this planet long enough, that our descendants thousands of years from now won't look back and curse at us for being idiots and deviating from celestial time.
Google probably knows a lot more:
UTC site:rfc-editor.orgFor the last few weeks, I've been trying to increase my productivity by getting rid of time tracking. So I decided to hide my computer's clock.
Sometimes, like when I have an appointment, I still need to check what time it is. Googling "time" doesn't always work (I don't know why exactly). So I bookmarked this site [1] but the information density is so high that I need to scan the page in order to get the time.
Time.is works quite well, with useful customization options, though it still carries bits of useless information (like the time zones at the bottom). But the time's font size is big enough to trigger instant focus.
UPDATE: as guptaneil pointed out, clicking the time (or navigating to http://time.is/just) removes all the clutter. Thanks for the tip.
Firefox latest.
But I almost never have a terminal open (and don't have a shortcut for that either) whereas Firefox almost always is. So I'm just 1 click away rather than 4 characters away.
You taught me something though (I highly prefer typing on a keyboard than using a mouse or, worse, a touchpad) and I wish I had to spend more time in a terminal.
The problem is exacerbated by the fact that most systems rely on OS tzdata instead of shipping it themselves, yet in many places the administration of the OS is separated / walled off from the devs who maintain the apps which actually suffer from the bugs.
I feel bad for users who live in countries whose governments play with DST law on a whim, because they are certainly destined to encounter bugs throughout the Internet because it isn't always reasonable to ask all administrators around the globe to patch all production systems in a matter of a few days.
if (wn == 1) pwn = '1-ին շաբաթ';
It looked like something related to week number; looks interesting. if(p_wn=='hy'){if(wn==1)pwn='1-ին շաբաթ';else pwn=wn+'-րդ շաբաթ'}
So if the locale is "hy" (Armenian), and the week number is one, set the string to "1st week", else set the string to "#th week" (both in Armenian).Unlike English, which also has exceptions for "2nd" and "3rd", Armenian only uses a different suffix for "1st".
disclosure: worldtimebuddy founder.
At least there is no RFC 867 and RFC 868 date on port 37 and port 13.
This is deprecated, I know, but rdate is still the easiest way to fix the date on a system which do not require precision. I did run my own minimal daemon on my DSL modem for the various gizmos I have that include busybox (thus rdate) and where recompiling to get a ntp would be overkill. (the right day and the right hour are more than enough)
time.nist.gov removed RFC 867 (port 13) and 868 (port 27) support. time-nw.nist.gov kept it a bit longer, then I used by DSL modem, which went in RMA and so guylhem.org is also down.
I'll try to email the author and offer to give a hand.
sntp pool.ntp.orgTechnical excellence is not always required, and having more choices usually is a good idea.
It is labeled "DCF signal - precision time", yet is off by hours most of the time (jumps randomly).
I keep it for the entertainment value. Guests always have a good chuckle when they enter the bathroom at 16:41 and leave it at 23:41.
The add-on would be simpler, as a text-select and right click could show the selected time in your own time zone in the right-click menu.
It's something I've missed every single time some press conference or event is announced, and it just says 12:00 EST.
Your clock is 0.2 seconds slow.
Accuracy of synchronization was ±0.625 seconds
If the result is within the margin of error, wouldn't it be better to just not tell me at all?So many of them like Time.gov rely on stuff like Flash or Java, or 1998 style Javascript, which I don't really dig. Definitely a nice little hole there for making something cool.
My little Ubuntu machine is -0.018 seconds (±0.009 seconds).
My MBP is -0.012 seconds (±0.021 seconds).
I recommend you add a percentile score of exactness, along with breakdowns based on platform, and suggestions about what to do if the percentile is disappointing.
I used a simple shell script to query timezone info to find world time in CLI https://gist.github.com/2020097
# yum install ntpdate
# ntpdate -u ntp-1.vt.edu
# hwclock -w
"Your time is exact!"
My ZTE Blade/CM7 was obnoxiously bad at keeping time, probably a software bug or something.
I thought redhat installed ntpd or chrony by default. I know chrony is the default for the next fedora release. If you have ntpd/chronyd installed your advice is horrible and not just because you pointed everyone to Virginia Tech's time server.
# yum install chrony
# systemctl enable chronyd.service
# systemctl start chronyd.service
Sorry if the (working) pointers before were horrible. Hopefully this is more useful - the servers used are {N}.fedora.pool.ntp.org.
You were downvoted for adding nothing to the discussion.