# What time is it? How do you determine the current, precise time? **URL:** \ **Category:** Factual Questions\ **Created:** [April 29, 2025, 2:35pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657 "2025-04-29T14:35:34Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![JohnGalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johngalt/32/184_2.png) [@JohnGalt](https://boards.straightdope.com/u/JohnGalt)\ **Post date:** [April 29, 2025, 5:14pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/21 "2025-04-29T17:14:15Z")
I had a Radio Shack weather radio that also had a band for WWV and WWVH. It was as accurate as you could get at the time. Years ago we had a vacation on Kauai, which has a Department of Commerce building broadcasting WWVH, located at a Navy base. On a whim, since we were nearby, I thought it would be interesting to visit. Explaining why I was there at the gate, they let us through and directed us where to go. We entered the building, where one of the engineers looked up, set down his lunch of a sandwich and chips, and led us into the lab with the HP (?) frequency generators and radio transmitters. I could have turned a dial or flipped a switch, but he watched me quite closely. I didn’t touch anything, I promise! We talked a bit about the equipment and antennas, since I had a BSEE degree and could relate. We then left (and found a cafe serving coconut cream pie, yum!). I don’t think you can do visit there any longer. ---
**Author:** ![XOldiesJock](https://avatars.discourse-cdn.com/v4/letter/x/ec9cab/32.png) [@XOldiesJock](https://boards.straightdope.com/u/XOldiesJock)\ **Post date:** [April 29, 2025, 5:18pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/22 "2025-04-29T17:18:24Z")
> [@Bullitt](#): > > _I frequently listen to CBS News Radio (KCBS in San Francisco, 740 AM and 106.9 FM) and every hour on the hour they play a chime, a ding, at exactly on the hour. But for a long time lately that ding has consistently been about 10 or 15 seconds late. I wonder why that is?_ Having worked for CBS Radio several years ago (when CBS still owned radio stations) it was standard procedure for all of their stations to be on a 15 second digital delay at all times, even the music stations, just in case someone said something they shouldn’t have. What you’re hearing on your radio is the delay. I would think the current owners (Audacy) would have the same procedure in place. ---
**Author:** ![Pork\_Rind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pork_rind/32/111_2.png) [@Pork\_Rind](https://boards.straightdope.com/u/Pork_Rind)\ **Post date:** [April 29, 2025, 5:22pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/23 "2025-04-29T17:22:14Z")
I am a total time nerd and track the accuracy of all my mechanical wristwatches every day, using an app to plot variation over time. For that I use time.is and find that its accommodation for network latency is more than enough for me. I have a ham radio on my desk, and tuning to WWV demonstrates that the website and the time broadcast are so tightly aligned that I cannot hear/see any difference. Any discrepancy is below my physical perception limit. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [April 29, 2025, 5:55pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/24 "2025-04-29T17:55:20Z")
Install a Linux server. Install an NTP server app (AlmaLinux comes with `chrony` available in default repositories and, if the system was set up as a server, pre-installed). Configure `chronyd` to poll stratum 2 servers. Allow `chronyd` to serve NPT responses to clients in the local network. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 29, 2025, 6:05pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/25 "2025-04-29T18:05:26Z")
> [@RitterSport](#): > > There used to be a time phone number when I was a kid that I would call, I think run by the phone company. In my 'hood it was 853-1212. A quick Google search shows that was the number in many area codes. > [@TriPolar](#): > > The time on the phone was reported every 10 seconds. IIRC the pleasant recorded voice would mark the time with the word ‘exactly’, IOW ‘The time is now 10:56 and 10 seconds **exactly** ’. In my youth: > At the tone, the time will be … 10 … 56 … and 10 seconds … exactly [BEEP] [She was Siri before Siri was cool. I still think of her from [wait for it] time to time] Good times. I use the [time.gov](http://time.gov) website, but only twice a year – beginning and end of DST. Clocks and watches are so damned accurate these days, I’m rarely far off on any watch, clock, or device (that doesn’t automatically sync wirelessly). ---
**Author:** ![Noelq](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/noelq/32/16438_2.png) [@Noelq](https://boards.straightdope.com/u/Noelq)\ **Post date:** [April 29, 2025, 6:07pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/26 "2025-04-29T18:07:08Z")
> [@XOldiesJock](#): > > > [@Bullitt](#): > > > > _I frequently listen to CBS News Radio (KCBS in San Francisco, 740 AM and 106.9 FM) and every hour on the hour they play a chime, a ding, at exactly on the hour. But for a long time lately that ding has consistently been about 10 or 15 seconds late. I wonder why that is?_ > > Having worked for CBS Radio several years ago (when CBS still owned radio stations) it was standard procedure for all of their stations to be on a 15 second digital delay at all times, even the music stations, just in case someone said something they shouldn’t have. What you’re hearing on your radio is the delay. I would think the current owners (Audacy) would have the same procedure in place … THANK YOU SO MUCH. This has been bothering me for years! Now it makes sense why the time is off on the radio! Perfect! ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [April 29, 2025, 6:09pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/27 "2025-04-29T18:09:10Z")
> [@DavidNRockies](#): > > In my 'hood it was 853-1212. I’m nearly positive it was 555-1212 in Queens back in the 70s/80s. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 29, 2025, 6:26pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/28 "2025-04-29T18:26:25Z")
> [@DavidNRockies](#): > > In my youth: > > > At the tone, the time will be … 10 … 56 … and 10 seconds … exactly [BEEP] Yes! That was it. There was the tone at the end. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [April 29, 2025, 6:57pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/29 "2025-04-29T18:57:23Z")
If you still have a cable box with a time on it, I found that the time on those is exact, at least to the second. The downside is you have to wait for the minute to tick by. ---
**Author:** ![Pork\_Rind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pork_rind/32/111_2.png) [@Pork\_Rind](https://boards.straightdope.com/u/Pork_Rind)\ **Post date:** [April 29, 2025, 7:19pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/30 "2025-04-29T19:19:19Z")
> [@RitterSport](#): > > A GPS unit will have the precise time, because differences in reported time from various satellites is how it determines where you are. One thing to note: > GPS, Global Positioning System time, is the atomic time scale implemented by the atomic clocks in the GPS ground control stations and the GPS satellites themselves. GPS time was zero at 0h 6-Jan-1980 and since it is not perturbed by leap seconds **GPS is now ahead of UTC by 18 seconds** ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [April 29, 2025, 7:24pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/31 "2025-04-29T19:24:56Z")
Whoa. Do various devices then make an adjustment by subtracting 18 seconds from the GPS time? I’m learning so much from this thread! First, the rock-solid 60 Hz is no longer rock solid, and now GPS is off by 18 seconds. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [April 29, 2025, 7:26pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/32 "2025-04-29T19:26:34Z")
> [@DavidNRockies](#): > > In my youth: > [@RitterSport](#): > > I’m nearly positive it was 555-1212 in Queens back in the 70s/80s. > [@TriPolar](#): > > Yes! That was it. There was the tone at the end. Still exists. See [Post #8.](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/8) It does this only on the minutes though with a faint ticking sound while you wait. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 29, 2025, 7:29pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/33 "2025-04-29T19:29:00Z")
ETA: @Pork_Rind 3 posts up. you folks are fast. Although the GPS system also knows about that 18 seconds. And “GPS time” itself is only used internally between the control center, the satellites, and the receivers. So IMO there’s no obvious way to know whether your GPS receiver is displaying raw GPS time or UTC derived from GPS time. Sure, your owner’s manual might say, but maybe it doesn’t. I have an app on my Android phone for monitoring GPS satellites. It’s a geek toy, not a navigator: > > > Get a faster GPS fix! ...and so much more..... The time it displays is a few seconds off the time on my phone. But nowhere near 18 seconds off. So I suspect it’s displaying GPS time with the correction. And my phone is a few seconds off UTC. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 29, 2025, 7:43pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/34 "2025-04-29T19:43:48Z")
I missed that. Thank you. I don’t have shortwave, but … - The broadcast facility is walking distance from me. I can always just show up and ask them what the time is, and - I found an online ‘simulator’ that mimics the WWV/WWVH broadcasts and claims good fidelity to NIST: > **[WWV Simulator](https://wwv.mcodes.org/)** I remember their broadcasts from high school when I _did_ have a shortwave receiver. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 29, 2025, 7:55pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/35 "2025-04-29T19:55:45Z")
> [@DavidNRockies](#): > > In my 'hood it was 853-1212. Thanks > [@DavidNRockies](#): > > In my 'hood it was 853-1212. In my hood the last 4 digits could be anything. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [April 29, 2025, 7:56pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/36 "2025-04-29T19:56:57Z")
IIRC, that was true for us, too. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 29, 2025, 8:03pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/37 "2025-04-29T20:03:26Z")
I remember because there was a ‘standard’ or advertised number. One day a friend of mine was calling time and then said, “oops, I forgot a number in the middle” and then just tacked it on at the end. Imagine my surprise when that worked! It was then he let me in on the fact any last 4 numbers worked. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [April 29, 2025, 8:27pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/38 "2025-04-29T20:27:28Z")
In my neighborhood, suburban Maryland, 555-1212 was directory information, which for many years was a live operator who would read out your requested number. Eventually it was automated: they would listen to your request, say “Hold for the number,” and an automated voice would read it out. 844-1212 was time. 844=TI4, TI standing for TIME. I think any other numbers could be substituted for 1212 for either. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [April 29, 2025, 8:36pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/39 "2025-04-29T20:36:28Z")
> [@TriPolar](#): > > The time on the phone was reported every 10 seconds. IIRC the pleasant recorded voice would mark the time with the word ‘exactly’, IOW ‘The time is now 10:56 and 10 seconds **exactly** ’. Not in CA, circa 35 years ago. The message was: At the tone, Pacific Standard Time will be: Four. Twenty-two. And fifteen seconds. BEEEEP." ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [April 29, 2025, 8:45pm UTC](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657/40 "2025-04-29T20:45:04Z")
> [@Bullitt](#): > > How do you determine that? I like to build clocks or clock-adjacent objects and I use ESP32 microcontrollers that can use NTP to sync their time, and also use a library to adjust for Daylight Saving Time. Works well, down to a fraction of a second. One clock I made in two parts, one each for hours and minutes. Instead of adding a communications link, I just sync each individually. It’s close enough that I can’t see any lag by eye (i.e., 59-\>00 happens at exactly the same time as 11-\>12). [Previous page](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657.md?page=1) [Next page](https://boards.straightdope.com/t/what-time-is-it-how-do-you-determine-the-current-precise-time/1017657.md?page=3)