GPS Receiver For Clock Time?

 

I have been using my old Sony Dream Machine AM/FM/TV/Weatherband clock radio for years now. When I bought it years ago, I liked having the ability to receive TV audio. That was before digital (ATSC) TV, so that is no longer an option. Anyway, I like how it works, EXCEPT that it does not keep great time. That has prompted me to start looking for a suitable replacement.

With regards to keeping accurate time for consumer grade devices, it seems like there are several different methods these days.

One is just a simple clock that is set manually. Just like my Sony has.

Some clock radios have the ability to get a signal from a FM broadcast station. Not all FM broadcast stations send this, however. The other problem is some send out inaccurate time!

Some radios have the ability to receive a signal from WWVB. These so called atomic clocks display very accurate time. My experience, however, has been that some have quite a challenge receiving the 60 kHz frequency, particularly in the daytime.

Some get time from the internet. My Sony Dash HID-C10 displays very accurate time. It has wifi, so as long as it is connected to the internet, it has very accurate time.

Which brings me around to the GPS tie in. With GPS chipsets being reasonably priced, are there any clocks using time signals received from GPS?

I don't have an answer to

I don't have an answer to your question. But I will comment, that it's my experience that the Atomic clocks really only check around mid-night. You're correct that the WWV signal is pretty weak in the day time, but since the clocks keep pretty good time, they don't usually do a regular check in the daylight hours.

I have also found that placing them on a west facing wall helps a lot.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

Most everything we have has time updater

Our Computers, TV's, Fitbit, Ooma and cell phones, our alarm radios are manually set with battery back up (Change battery annual) very accurate, so really see no need for another system.

Reduce signal obstructions

phranc wrote:

...
I have also found that placing them on a west facing wall helps a lot.

Homes that have foil faced insulation sometimes block the WWV signal. If you can reduce the obstacles between the atomic clock and the direction facing Ft Collins Colorado, these clocks do typically sync in the middle of the night. In extreme situations, placing them by a window often helps.

--
"There's no substitute for local knowledge" nüvi 750, nüvi 3597

Never saw a gps synched clock

Jim1348 wrote:

...
Which brings me around to the GPS tie in. With GPS chipsets being reasonably priced, are there any clocks using time signals received from GPS?

WWV and GPS time sync share the same potential problem. They need a relatively unobstructed view of the transmitter. Most quality GPS units will get some signal through a simple sheetrock ceiling and composition roof, but in buildings with a metal roof and particularly additional stories above the GPS, the signal is about zero unless near a window with a view of the sky.

Your cell phone stays very accurate from the time data sent to it from the cell towers. I've never thought if a unregistered phone will still set the time if powered on. If it will, then a clock with a LTE receiver in it would keep accurate time assuming you don't have to have a deal with a carrier.

--
"There's no substitute for local knowledge" nüvi 750, nüvi 3597

WWVB

I have one Weather Station with Atomic Clock that I use to set all the clock in the house by, in the Tampa area the signal is pretty reliable after midnight, usually by 2am the clock makes the daily correction if needed.

--
Garmin 38 - Magellan Gold - Garmin Yellow eTrex - Nuvi 260 - Nuvi 2460LMT - Google Nexus 7 - Toyota Entune NAV

Yes

TXRVer wrote:
Jim1348 wrote:

...
Which brings me around to the GPS tie in. With GPS chipsets being reasonably priced, are there any clocks using time signals received from GPS?

WWV and GPS time sync share the same potential problem. They need a relatively unobstructed view of the transmitter. Most quality GPS units will get some signal through a simple sheetrock ceiling and composition roof, but in buildings with a metal roof and particularly additional stories above the GPS, the signal is about zero unless near a window with a view of the sky.

Your cell phone stays very accurate from the time data sent to it from the cell towers. I've never thought if a unregistered phone will still set the time if powered on. If it will, then a clock with a LTE receiver in it would keep accurate time assuming you don't have to have a deal with a carrier.

Yes, an unregistered cellphone will still get network time. It will also call 911 in an Emergency. It doesn't have to be an LTE. My CPAP uses 3g and keeps time just fine.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

GPS and actual time

Am I remembering correctly that GPS satellites have never corrected for leap seconds? If true, there have been quite a few since GPS came to be.

I also prefer "atomic" or radio-controlled clocks and watches. I set the watches in a window facing Colorado nightly and the house clocks wherever they are in the house and know that I've gotten updates daily in AZ and WI. Updates may be tougher in the eastern US and Canada. I believe most run using a quartz crystal between daily radio updates. For me, this is the best option for folks who reliably get the radio signals.

A bonus with these is that they auto adjust for DST although for me in non-Navajo AZ, I have to turn off the autoDST mode and for my one adio-controlled clock that can't disable autoDST, I have to switch from MT to PT during DST. sad

Hmm, it may be that the GPS receiver corrects GPS time by knowing and adjusting for leap seconds, at least for some GPS clock manufacturers:

https://www.hodinkee.com/articles/leap-second-added-to-world...

My findings

I have several radio controlled clocks & watches and live approximated 1875 miles from Colorado & would say without hesitation that I successfully receive the signal 99% of the time.

As others have said the signal is stronger during the nighttime & my clocks & watch automatically sync between 00.00 & 05.00.

I have a watch which is able to receive both the 60 kHz or GPS time & position data & interested in learning from others if GPS does exist for clocks question

For additional information :

http://www.poi-factory.com/node/23526

--
Nüvi 255WT with nüMaps Lifetime North America born on 602117815 / Nüvi 3597LMTHD born on 805972514 / I love Friday’s except when I’m on holidays ~ canuk

.

I just use cell phones for my clocks. The towers are GPS-timed from the nist stations, and are very accurate.

--
nüvi 3790T | nüvi 775T | Those who make peaceful revolution impossible, will make violent revolution inevitable ~ JFK

Clocks

I have two alarm clocks bought about 10 years ago at I think was "Brockstone". The forecast the weather and very frequently log onto an atomic time server. They have very accurate time displayed.

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Nuvi 350 long gone, Nuvi 855LMT Retired now, Nuvi 2797LMT, SmartDrive 50 LMT-HD, 3790LMT now my daughters. Using Windows 10. DashCam A108C with GPS.

Why?

Jim1348 said: "Which brings me around to the GPS tie in. With GPS chipsets being reasonably priced, are there any clocks using time signals received from GPS?"

I don't get what you are trying to do.

Do you want a clock in your home that is also a GPS?
Do you want the clock in your car to tap the GPS or NAV system?

I don't see any benefit from this line of thought.

--
I never get lost, but I do explore new territory every now and then.

Good point ...

TXRVer wrote:
Jim1348 wrote:

...
Which brings me around to the GPS tie in. With GPS chipsets being reasonably priced, are there any clocks using time signals received from GPS?

WWV and GPS time sync share the same potential problem. They need a relatively unobstructed view of the transmitter. Most quality GPS units will get some signal through a simple sheetrock ceiling and composition roof, but in buildings with a metal roof and particularly additional stories above the GPS, the signal is about zero unless near a window with a view of the sky.

Your cell phone stays very accurate from the time data sent to it from the cell towers. I've never thought if a unregistered phone will still set the time if powered on. If it will, then a clock with a LTE receiver in it would keep accurate time assuming you don't have to have a deal with a carrier.

I like this idea ...

Smartphone

GPS time is not as accurate as that provided by WWV which uses the cesium clock in Fort Collins CO. GPS time can differ by several seconds. If a high degree of accuracy is required, GPS time is not the way to go.

Timekeeping is a good use for an old or unused smartphone. I have a couple of older Apple phones with alarm clock apps that I keep around the house. They don't require a cellular carrier if wifi is available. I even use one as an alarm clock when travelling since most hotel chains now offer free wifi.

very different frequencies

As others have mentioned WWVB transmits at 60 kHz, while the consumer GPS frequency is near 1.6 GHz.

Those are wildly different frequencies regarding propagation characteristics so the comment here that they face the same problem in reaching a particular receiver in your home is rather misplaced. In particular the very low WWVB frequency will go right through or around things which pose severe GPS reception problems.

I live in New Mexico, so the distance to the WWVB transmitter in Colorado is very short, and my experience with WWVB-receiving clocks and watches has been good. But when I gave the same model of watch I liked a lot to my father-in-law, he had no luck with it receiving time in Hanover NH.

Your luck with WWVB will depend a lot on where you live, and also somewhat on the construction of your home and the position of your receiver within the home. New England is one of the worst locations in the lower 48 for WWVB reception.

The signal "bounces" at night, differing on different nights, so sometimes you may get a successful time sync far away. To my great surprise, my watch received time one of the four nights I slept in Belize.

--
personal GPS user since 1992

From the NIST

From the NIST webpage;

Broadcast Frequencies
WWV operates in the high frequency (HF) portion of the radio spectrum. The station radiates 10000 W on 5 MHz, 10 MHz, and 15 MHz; and 2500 W on 2.5 MHz and 20 MHz. Each frequency is broadcast from a separate transmitter. Although each frequency carries the same information, multiple frequencies are used because the quality of HF reception depends on many factors such as location, time of year, time of day, the frequency being used, and atmospheric and ionospheric propagation conditions. The variety of frequencies makes it likely that at least one frequency will be usable at all times.

All are unencrypted and can be received by any receiver that can operate in those bands.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

GPS Time Is Accurate

bdhsfz6 wrote:

GPS time is not as accurate as that provided by WWV which uses the cesium clock in Fort Collins CO. GPS time can differ by several seconds. If a high degree of accuracy is required, GPS time is not the way to go.

GPS time is at least as accurate as WWVB. If it was "several seconds off", your position error on the earth using GPS would be gigantic compared to the few feet it actually is. Also, astronomers use GPS time now for high-precision occultation timings. The several seconds error you claim would be totally unacceptable in that application.

I'm curious as to why you think GPS is less accurate than WWV?

iPhone

bdhsfz6 wrote:

GPS time is not as accurate as that provided by WWV which uses the cesium clock in Fort Collins CO. GPS time can differ by several seconds. If a high degree of accuracy is required, GPS time is not the way to go.

Timekeeping is a good use for an old or unused smartphone. I have a couple of older Apple phones with alarm clock apps that I keep around the house. They don't require a cellular carrier if wifi is available. I even use one as an alarm clock when travelling since most hotel chains now offer free wifi.

I for one can live with a few seconds error!

As for the iPhone, the bad about it is they have to be ON for the alarm clock to work. I had a NOKIA phone where you could set an alarm and then turn it off. It would wake up to wake you up.

--
Nuvi 350 long gone, Nuvi 855LMT Retired now, Nuvi 2797LMT, SmartDrive 50 LMT-HD, 3790LMT now my daughters. Using Windows 10. DashCam A108C with GPS.

WWVB not same as WWV

phranc wrote:

From the NIST webpage;

Broadcast Frequencies
WWV operates in the high frequency (HF) portion of the radio spectrum. The station radiates 10000 W on 5 MHz, 10 MHz, and 15 MHz; and 2500 W on 2.5 MHz and 20 MHz.

Yes, but the WWVB-receiving clocks (often marketed as "atomic") don't listen to any of those but instead listen to the WWVB 60 kHz signal, which has quite different transmission and obstacle penetration characteristics.

--
personal GPS user since 1992

My bad. I read through too

My bad. I read through too fast and didn't catch WWVB.

--
Frank Nuvi 3597LMT 37.322760, -79.511267

GPS is Accurate Enough for Me

Melaqueman wrote:
bdhsfz6 wrote:

GPS time is not as accurate as that provided by WWV which uses the cesium clock in Fort Collins CO. GPS time can differ by several seconds. If a high degree of accuracy is required, GPS time is not the way to go.

Timekeeping is a good use for an old or unused smartphone. I have a couple of older Apple phones with alarm clock apps that I keep around the house. They don't require a cellular carrier if wifi is available. I even use one as an alarm clock when travelling since most hotel chains now offer free wifi.

I for one can live with a few seconds error!

As for the iPhone, the bad about it is they have to be ON for the alarm clock to work. I had a NOKIA phone where you could set an alarm and then turn it off. It would wake up to wake you up.

I can as well. Just making a point for those who insist on a high degree of accuracy.

The old phones I own have weak batteries and I just leave the power cube attached.

Depends on Your Definition of "Accurate"

RebHawk wrote:
bdhsfz6 wrote:

GPS time is not as accurate as that provided by WWV which uses the cesium clock in Fort Collins CO. GPS time can differ by several seconds. If a high degree of accuracy is required, GPS time is not the way to go.

GPS time is at least as accurate as WWVB. If it was "several seconds off", your position error on the earth using GPS would be gigantic compared to the few feet it actually is. Also, astronomers use GPS time now for high-precision occultation timings. The several seconds error you claim would be totally unacceptable in that application.

I'm curious as to why you think GPS is less accurate than WWV?

GPS time is extremely accurate when compared to itself. That is why it provides minimal position error. GPS time is not sync'ed with UTC and is currently 18 seconds ahead. This is mainly due to the fact that UTC is periodically adjusted (leap seconds, etc) where as GPS time is not.

The following website provides information on various time sources and lists links to other sources of information on the subject.

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

The following is an excerpt from the astronomy web page of Ohio State University:

"However, care must be taken when using GPS as an astronomical time reference. Unlike UTC, GPS is NOT adjusted for leap seconds. GPS time was last synchronized with UTC on 1980 January 6, and as of 2006 January 01, GPS is ahead of UTC by 14 seconds. Each GPS satellite transmits the UTC correction parameters as part of the navigational data stream, and most good GPS receivers include software to make the conversion for you transparently. Care should be taken to verify that you are indeed reading the UTC time and not the GPS time when you query your GPS receiver for "the time".

The OSU Astromomy web page is available here:

http://www.astronomy.ohio-state.edu/~pogge/Ast350/timesys.ht...

even a forecast

As the previous post mentions, the GPS constellation birds constantly transmit the current correction between GPS time and UTC. Not only that, but they foretell the next leap second months in advance.

So if your GPS receiver is in the range of 20-ish seconds off, blame a lazy design spec for the receiver--not some inherent fault of the GPS system. After all, the GPS time does not "do" daylight saving time, time zones, nor, for that matter, maps.

But we expect a modern, decent unit, to give us all of these things.

The one exception that makes displayed GPS receiver time nowhere near the nanosecond level internal accuracy is that I don't think the receiver designers take much care to compensate out the delays of the output display path (liquid crystal displays don't change to the new opacity in anything remotely near a nanosecond--and there are other hardware and software opportunities for delay).

If you own a short-wave or worldband receiver (I've not turned mine on in over a decade), then listening to the human-compatible WWV signal is probably the best way to check your GPS display for accuracy. Second best, but available to far more of us, is to use the web site www.time.gov.

--
personal GPS user since 1992

Cell Phones As Clocks

This actually reminds me of one of my projects this past weekend. I was thinking about how we have several cell phones around the house that were no longer being used, since they had been replaced by newer phones.

I bought some Velcro and have attached some of these old phones to clock radios around the house. I have installed the app Big Digital Clock from the Google Play store.

In our master bedroom bathroom, where the AM-FM clock radio is that I use for an alarm, never kep great time. Now I have a device attached to it that displays more accurate time!

One thing that I did find interesting, however, was when I held the phones side by side running that app. One of the phones had an 8 second difference from the other ones. All were on the same wifi network, so I was somewhat surprised that they didn't all display the same time.

https://play.google.com/store/apps/details?id=de.andreas1724...

Does someone bother?

Jim1348 wrote:

One thing that I did find interesting, however, was when I held the phones side by side running that app. One of the phones had an 8 second difference from the other ones. All were on the same wifi network, so I was somewhat surprised that they didn't all display the same time.

I don't think the Wifi network gives time information to clients. But if it is internet connected, then clients that bother to try can get the right time from any of a number of internet sources provided for that very purpose. Then the question (a bit like the GPS receiver situation I discussed above) is whether all the design decisions bother passing that correct time on to the display.

Forgetting Wifi use of retired phones for a moment, and moving to live cell phones--again there is something of an analogy to the GPS receiver "does anyone bother?" issue. The cell networks need very precise frequency and timing information just to perform the backbone network function. (in fact coms network hardware was a very early user of GPS, before there were enough birds in the air to provide reliable navigation). Yet I have seen a live cell phone displaying a time in error by tens of seconds, though most others I have seen are adequately accurate.

My first job out of college in 1974 was to design a liquid-crystal display watch chip. It just traumatizes me to see design decisions made which throw away easily available time accuracy on the path from source to user.

--
personal GPS user since 1992

GPS time accuracy

I have a watch that can sync location + time with the GPS function & after having done so the time is as accurate as the other watches that received the WWVB signal.

Both the radio controlled watches + the GPS watch are also in sync with the following site : https://www.time.gov/

GPS is superior in areas where your watch isn't able to sync with the atomic clock signals. (Example if your in Africa).

Atomic Clock Signals:

Location Frequency Callsign
USA (Fort Collins, CO) 60kHz WWVB
United Kingdom (Anthorn)60kHz MSF
Germany (Mainflingen) 77.5kHz DCF77
Japan (Fukushima) 40kHz JJY
Japan (Kyushu Island) 60kHz JJY
China (Xi’an) 2.5/5/10/15MHz BPM

--
Nüvi 255WT with nüMaps Lifetime North America born on 602117815 / Nüvi 3597LMTHD born on 805972514 / I love Friday’s except when I’m on holidays ~ canuk