Some Observations of Errors in Time Standard Sources and Problems wth RC Clocks

[Precise]

I realize that much of this has appeared in various threads, but thought it worthwhile to highlight this issue for those who may have missed some of the prior mentions. Below I list some of my personal observations and experiences. I encourage others to contribute their experiences to this thread.

My only trusted source is WWV short wave radio. I live in the San Francisco area and only get good reception at night. Everything listed below has been compared to WWV short wave radio.

1. I've observed internet time errors at the USNO site of up to ten seconds.

2. I have one radio-synced watch, a Casio PAW-2000. It doesn't sync in my home office, but it usually syncs if I hang it in a window facing Colorado. One thing I like about this watch is that it displays the time and date when it last synced.

3. Junghans MEGA alarm clock: When I first bought it, it did not sync in my office all night despite sitting next to my short wave radio which was receiving a clear signal. The dealer told me that the Junghans received WWVB at 60 Khz. That's a long wave signal which I can't even receive on the short wave radio which I use to receive 5, 10 and 15 Mhz. When I moved the Junghans to the Colorado facing window it synced in a few minutes. Once synced, it has maintained itself nightly in my office. It has a readout of how many nights since sync.

4. Seiko Global Radio Wave Alarm clock QHR007G: Doesn't sync in my office, syncs about half the nights that I leave it in my Colorado facing window. Has an icon to indicate that it has synced, but the icon doesn't keep track of elapsed nights since sync and disappears in a day or two.

5. Sangean RCR-3 clock radio. I had high hopes for this one because Sangean makes decent short wave radios. It took five days to sync in my office. It doesn't keep a record of elapsed nights since prior sync. Every hour (day and night) it attempts to sync for 15 minutes - usually without success. I extended the FM antenna but that had no effect. It probably uses 60 Khz with a ferrite loop stick rather than the wire FM antenna.

6. My Verizon - Motorola Droid-X smartphone and my Garmin GPS III both are consistently 14 to 17 seconds off standard time. There have been some posts on WUS explaining that these devices have not kept up with accumulated leap seconds over the years.

[johnny action]

Time is relative.

[ronalddheld]

I though cell phones which use GPS time are now off by an addditional second.

[Precise]

I though cell phones which use GPS time are now off by an addditional second.

Please elaborate. My cellphone is still off like I originally posted.

[ronalddheld]

GPS time does not incorporate leap seconds. There have been 15 since its zero point. If the cell phone servers use GPSDOs as their time standard, then your time will be 15 seconds fast + any variations on top of that.

[Andrew McGregor]

GPS time does not incorporate leap seconds. There have been 15 since its zero point. If the cell phone servers use GPSDOs as their time standard, then your time will be 15 seconds fast + any variations on top of that.

Not necessarily... the GPS also transmits the offset to UTC, and the output from the GPS is supposed to be UTC, not GPS reference time. So if this is true, the GPS chipset in the phone has a serious bug.

[Precise]

In addition to the 15 second offset, I have found GPS time to vary over a 3 second range. I was very surprised. I had expected GPS time to be the gold standard.

Alan

[ronalddheld]

yes the leap seconds could be used, but with my verizon phones, it seems not to be.

[Andrew McGregor]

In addition to the 15 second offset, I have found GPS time to vary over a 3 second range. I was very surprised. I had expected GPS time to be the gold standard.

Alan

GPS pretty much is the gold standard... this is all about how messed up the operating systems in mobile phones are, not the GPS itself.

[Precise]

GPS pretty much is the gold standard... this is all about how messed up the operating systems in mobile phones are, not the GPS itself.

I have observed 2 second variability on my Garmin GPS III, stand alone GPS. At the time I bought it, it was one of their most expensive hand-held models. It has impressive location averaging capability. But it's about ten years old.