[time-nuts] Cell Phone time ?

Didier Juges didier at cox.net
Mon Nov 26 17:48:23 EST 2007

My old Motorola V60x (CDMA) did not automatically switch time zones during
travel, I had to power down and back up, but the newer Motorola CDMA phones
apparently switch time zone automatically. I have not checked how accurate
the time was, but that's an interesting question. 

I also have a GSM Blackberry that switches time zones automatically and sets
itself up at power up automatically, and a GSM Motorola Razr which is
probably defective because even though it is set to automatically fetch time
from the network, it never does (not just changing time zone, but even at
power up) and has to be set manually. The phone otherwise works perfectly
:-( It's hard to imagine that something could be broken and prevent the
phone from fetching time, but would not prevent the phone from working.

Strange that this issue did not get ironed out a long time ago...

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Mike Feher
> Sent: Sunday, November 25, 2007 6:18 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] Cell Phone time ?
> Well, this may seem like a dumb question to some of you, but, 
> it does have me baffled a little. I have noticed some time 
> ago that the time indicated on my cell phone is usually two 
> to four seconds ahead of GPS time. I was under the 
> impressions that most towers did use GPS time. Anyway, I 
> wrote it off to thinking that the phone is free running 
> unless connected to a call and hence the drift. I even tried 
> this theory by dialing my cell phone from my land line, and 
> low and behold, the times matched with GPS as long as I was 
> connected. Soon as I disconnected it was immediately off 4 
> seconds and eventually settled at about 2 seconds. Since 
> there is a signal indicator on the cell phone that is active 
> all of the time, it is obviously receiving something from a 
> local tower. Could that signal not have GPS time embedded in 
> it? It must have some, since going from one time zone to the 
> other switches the cell phone time automatically, but 
> obviously not accurately. It seems like a 2 second window is 
> pretty large to search to make all of those bits line up so 
> one can talk, or to even have the phone ring. Thanks for any 
> help in making me understand this small dilemma. Regards - Mike 
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960

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