Clocks That Get GPS Time Sync

I looked at a Seiko GPS referenced clock about a year ago and decided that at $300 it didn't have anything to offer over virtually the same clock, described as "atomic" at about $40.

By the way, the Seiko's were part of a line called Space Link. Numerous versions are on eBay but most ship from Japan. Be sure you want one, as they may not work well in some buildings.

Maybe about 12 - 13 years ago I bought 2 bedside clocks/alarm clocks dirt cheap (maybe $ 5.00 ea) on clearance at some thing like Sharper Image. They are an about 5" cube. They keep accurate time by the atomic clock. There is a little icon on the screen like a tower sending signals and it's always pulsing!

Clock in my car gets its time by GPS... Yet, I still have to set (or unset) the DST flag. One would think car knows where's it at, and time zone in use. Apparently not.

It's always baffled me that it will change time when I enter another time zone, but you have to toggle DST on and off.

Quoting https://www.nasa.gov/feature/jpl/what-is-an-atomic-clock

"Atomic clocks are used onboard GPS satellites that orbit the Earth, but even they must be sent updates two times per day to correct the clocks' natural drift. Those updates come from more stable atomic clocks on the ground that are large (often the size of a refrigerator) and not designed to survive the physical demands of going to space."

Up to 50 times more stable than the atomic clocks on GPS satellites, NASA's Deep Space Atomic Clock is intended to be the most stable atomic clock ever flown in space. It achieves this stability by using mercury ions.

Much appreciated.

2006 car seems to get its time from gps. Not to be confused with XM radio. Why because I replaced the XM antenna when it went bad and it had zero effect on AM/FM/navigation/time (learned all about FAKRA connectors, it's always a journey when your stuff is old).

Also funny is its navigation system is very palm piloty/cheesy. And its calendar happened to run out 12/31/22. Guess auto designers never think a person will drive a car 20+ years or a million miles, it just happens.

Also funny and I have mentioned it, home as programmed in the gps, is the original owner's home in FLA. Car started its life in a house with an 8 car garage, and now it sits outside 24/7/365 lol

GPS satellites do not correct their clocks for leap seconds so it's necessary for a GPS-UTC offset to be applied. Currently, the offset is 18 seconds:

https://timetoolsltd.com/gps/what-is-gps-time/

Some older GPS receivers had issues with applying the correct offset.

There's a site offering the various systems' current "time":

http://leapsecond.com/java/gpsclock.htm

At GPS synchronized clocks recently when my bedside alarm clock bit the dust. They are available but a bit pricey. It is also difficult to find one that suits every need. Projector, large digit, dual alarm, alternating time & temp display, etc. are hard, if not impossible to find right now.

Unfortunately, I had to settle for a WWVB synchronized model which rarely receives the signal. I'm located too far from the WWVB transmitter in Fort Collins CO. I only get a successful update once a week or so. Some WWVB models have an external antenna jack but I couldn't find a clock with the features I want that has this jack.

Congress is also debating the shutdown of WWVB for budgetary reasons. The school of thought is, it has been made obsolete by GPS time. No date has been set though. This would be unfortunate since it would render all existing WWVB clocks useless. the propagation of the low frequency WWVB 60KHZ signal gets into places that a GPS signal can't reach.

I have been a dedicated user of WWVB clocks and watches for decades. If Congress pulls the plug I shall be particularly annoyed at losing the use of my watch. It makes power from ambient light, so I never change a battery, wind it, or set the time, I just put it on in the morning it has the right time.

WWVB comes in just fine here in Virginia.

Sharper Image has atomic clocks for under $100

I have several clocks here in Philadelphia and all can synch without any issues. I do have one very old Radio Shack clock that will not synch during the day but a reset at night forces a synch and from then on it is OK. In that regard, NIST suggests that if you can force a synch in some manner, do so at a time where it is darkness at both your location and Ft. Collins CO.

If I'm not mistaken, the Atomic Clock brand clocks are programmed to begin trying ro synch at 00:00 local time.

Like several of you, I also have some "atomic" clocks and watches with the watches being solar-powered. So nice.

I had no problem syncing them living in northern Arizona, but now I'm in a high-rise steel/concrete building in Wisconsin, and my windows face northeast. All of mine try to sync daily first at 1AM, and continue once each hour up to 4 AM until successful. They will sync but I need to place them on a window sill to receive the signal. But then, the window sill is also the place the watches want to be to recharge on bright days.

I now see that Casio Oceanus watches, besides offering WWVB time syncing, can be had that also offer "cell phone Bluetooth" syncing besides the WWVB; and also now, some that offer GPS syncing along with WWVB.

I haven't tried any but I've seen LaCrosse Technology now offers atomic clocks they call "UltraAtomic" which can receive the WWVB signals where the old "atomic" clocks can't.

https://www.lacrossetechnology.com/pages/atomic-time

I have both a LaCrosse and a TempMinder Weather Station and both have
the clock that syncs to the Atomic Clock. The only problem that I have is that it is impossible to sync in a high rise apartment, that has reinforced steel walls and steel studs.

Unfortunately, I think I face the wrong way to sync from the balcony.

I have to take it out to the lawn, under battery power to get it to sync.

I had my first Casio G-Shock Solar Atomic watch for at least a dozen year, probably more. It finally stopped working a few months ago.

I replaced it with another Casio G-Shock solar atomic watch. This new one seems to get the WWVB sync in places that the old one didn't. I have speculated this it is a more sensitive receiver, but I am just shooting from the hip on that!

It will be interesting to see is "cell phone Bluetooth" syncing comes to clocks, too.

As far as I can see, the UltrAtomic clocks are limited now to a large wall clock in two finishes.

My weather station is an Ambient Weather model. It is WiFi connected so it can publish on Weather Underground. It knows my location coordinates (part of the initial setup) and I think it synchronizes time over the Internet using nist.gov rather than via the WWVB atomic clock signal although I am not sure of that. In any case, I have never had to tinker with the time on it since I initially installed it almost 2 years ago and the time is always spot on. The console is near a window though (facing SW), so it could probably receive the WWVB signal with no problem if that is how it does it.

The Amazon Echo Show models which have an LCD screen, sync automatically via their internet connection. If you set the location, they also adjust automatically for DST. Comparing with my WWV receiving Citizen and Casio watches, the Echo Show devices are very accurate.

I have a Lenovo Smart Clock that is similar.

There are pros and cons about the use of the internet to acquire high accuracy time via some connected device. One consideration is what is called latency and depending on your bandwidth it can cause errors of 0.1 to 0.2 second at any given time.

You can read more about the various factors affecting internet time at https://www.galsys.co.uk/news/ntp-servers-versus-internet-ti....

If you want to display time based on NIST you can go to the link at https://www.time.gov/.

I just checked. My Fitbit watch is about 3-4 seconds behind and my cell phone about 1 second.

I have nothing except my OCD, that needs to be more accurate.

Thanks for the info John from PA

I don't know what is actually done but recent latency can be computed by a set of pings.

I have a 2018 Chevy , I think I have it, I've never had to set my clock or adjust it in the 5 years.

For most of the clocks I own, I'm willing to accept any minor discrepancies between these time sources. I'm more concerned that they are self regulating and that I don't have to reset them for minor drift or twice each year for the ST / DST shift.

I am looking around again for any home office clocks that get their time sync from either NTP or GPS. Have the prices come down for GPS synced clocks?

I also see that some get a time from CDMA towers. I doubt that there is a consumer clock that uses that. I also wonder if there are an that use GSM towers.

https://www.beaglesoft.com/celsynhowworks.htm

Are you excluding devices (such as an old weather station I've had for years) that uses WWV?

I am looking at any products that offer solutions other than those that receive WWVB because some installations cannot receive signals from WWVB.

Is it a wall clock you are looking for?

I am open to either a desk clock or a wall clock.

If you have a smartphone, have you considered a Bluetooth clock? The clock will sync to the smartphone's time. Even some of the newer pricey wristwatches that can do daily radio or GPS syncs have the option to choose Bluetooth syncs.

These clocks are likely the least expensive way to keep a wall or desk clock on time to the second, auto adjust for Daylight Saving, etc. They're also great for folks on the East Coast of North America or in massive steel and concrete buildings, that are too far away or have too weak a signal for most radio syncs.

But this one uses internet time, which is very close:

https://www.amazon.com/DreamSky-Charging-Temperature-Humidit...

It reads the time and makes corrections when I plug in my phone to charge.

WWVB clocks and watches are quite satisfactory here in Albuquerque. The WWVB transmitter in Colorado is easily received usually.

But my father-in-law had no success in New Hampshire with a watch that worked fine here.

I'll need to keep my eyes open for Bluetooth models. A quick Amazon search did not turn up much, so maybe they are still scarce on the ground as yet. But that does seem to be a good idea.

I stumbled on the fact that there are some clocks available (including ones with classic clock face--hands and no digits) which rely on connecting to an internet time source using your WiFi to maintain accurate time.

All things considered, that seems, depending on product offerings available, likely to be a better technical solution than Bluetooth for some people.

The problem with a GPS clock will be signal.

I have a couple GNSS modules for Raspberry Pi. For accurate time you need PPS which requires a 3D fix which indoors can be difficult. I can only do it with the antenna sitting in a window (just like any of my Garmin GPS indoor). Up in the attic they work quite well.

Within 1ms of NISTs NTP servers.

remote refid st delay offset jitter

SHM(0) .GPS. 0 0.0000 -3.6195 4.1475
*SHM(1) .PPS. 0 0.0000 0.0003 0.0005
+time-a-g.nist.gov .NIST. 1 20.2026 0.3893 3.9131
+time-e-g.nist.gov .NIST. 1 21.0110 -0.3165 2.4873
+time-a-b.nist.gov .NIST. 1 54.6296 0.0014 1.3455
-time-e-b.nist.gov .NIST. 1 53.3618 -0.7359 2.2442
-time-a-wwv.nist.gov .NIST. 1 54.1911 0.1491 0.8527
-time-e-wwv.nist.gov .NIST. 1 53.0885 -0.2566 8.9551

Yesterday was one of my work from home days. I had a few free minutes and decided to check the World Time Clock on my Garmin Nuvi 360 and Nuvi 500. Once they were both powered up and receiving Global Navigation Satellite System signals, I checked the clock display. I noticed that they were one second off from one another. Not a huge concern in the grand scheme of things, but it made me wonder why there is a discrepancy.

Does anybody here have any thoughts on why there is a difference between the two?

Someone shared the URL below with me for the Geppetto Electronics GPS Clock.

https://www.tindie.com/products/nsayer/gps-clock

I also found out that there are Seiko Space Link GPW501W and GPW502W clocks that are marketed to Japan. The SQ768S looks similar to the GPW501W, but the SQ768S is "atomic" and the GPW501W GPW502W get their sync from GNSS satellites.

https://www.seiko-clock.co.jp/product-personal/digital/space...

https://www.seiko-clock.co.jp/product-personal/digital/space...

https://www.seiko-clock.co.jp/product-personal/digital/night...

Any source of correction for time is subject to error of one kind or another.

I live so close to Colorado that my WWVB-corrected clock commonly shows the wrong time starting about 6 p.m. the day before a daylight saving time change. There are two bits in the WWVB format that clarify the correct day to which a daylight saving time shift applies, but the clock design appears to rely on the time of day it chooses to listen to WWVB with usual reception capability so that people in most homes in the USA would never see the premature time change I see.

Separately, yesterday this same WWBV clock had an error syndrome I've never seen before. I suddenly heard an unexpected sound, and realized it was fast forwarding the hands. When it was done, it had taken up a new time that was off by two minutes from the correct time. It was two before, so the hand movement, which is forward only, had marched through 23:58 to get there.

I speculate that a reception error happened yesterday, giving me that 2 minute off display for a few hours. It tries to receive a few times per day, and one reception in the night must have succeeded, as it is correct again today.

If the new administration really doe abolish Daylight Saving time in the USA, we'll find out which devices have built into them an unfortunate dependence on the consistency of the US Congress.

I own a couple of Brookstone clocks which do automatic DST--but they assume the same dates for on and off that were in effect when they were designed.

Another error with WWVB is the distance of the receiver location from the transmitter in Fort Collins CO. For example, It takes a small fraction of a second for the signal to reach the east coast.

Right now I have a Garmin Nuvi 350 powered up and displaying the World Clock and the following time zones:

US - Pacific

US - Mountain

US - Central

US- Eastern

I also have an old Samsung Galaxy S9 on the Atomic Time Android app. At the moment they are in agreement to the seconds.

The also agree with the two websites below as well as my Casio GWM530A-1 wristwatch.

https://time.is/Chicago

https://www.time.gov/?t=24

My alarm clock has auto adjust for DST based on the date, but it is a feature that can be turned on or off so it wouldn't be ruined if DST was ever done away with.

I had two identical Emerson alarm clocks that had auto DST. One used the old DST dates and one used the new DST dates. I didn't notice it for years since the one using the old dates was in a spare bedroom. No way to adjust the dates.

We have a 2009 Sony clock radio that features "Automatic Time Set." It definitely does not use GPS or wifi, but it doesn't say it's set to an atomic clock, or otherwise explain *how* it automatically sets the time. It does, though; plug it in and it comes up with the time.
https://www.manualslib.com/manual/1395862/Sony-Icf-C414.html...

But the funny thing about it is that it is wildly inaccurate for a modern electric clock. It typically gains about a minute per month. Always has, in multiple geographic locations. To boot the process of overriding the automatic time set and adjusting the time manually is unintuitive and cumbersome. We keep the Sony Dream Machine around for comedy relief. Worst electric clock we ever had.

Your insights are very helpful.

That sounds broadly similar to my Brookstone, and I suspect it is using the same "trick". It just has a quartz time keeping function that runs all the time (until the backup battery dies) whether plugged in or not. So when you plug it in, it is just showing you the time it has kept all along. A really good quartz version should do a minute a year for error, so your minute a month is not so great. You may find, as I do with my Brookstone, that the time-keeping error is related to the backup battery voltage, so if it has been a while since you replaced it, you may find that replacing it changes the error rate.

The instructions at https://www.sony.com/electronics/support/res/manuals/4135/41... Indicate the unit has an internal CR2032 battery to keep the clock backed up. The radio time is initially set at the factory. The battery is replaceable. A single screw needs to be removed and a small “tray” is pulled out to access the battery.

That manual mentions that the clock is preset and kept by the battery.