Re: [time-nuts] How are iPhones' clocks set under LTE?
From: Paul In the US it tries [0-3].us.pool and my local address. It chooses the "best" three of those and then it chooses one. The list also shows (in pool.ntp.org) [0-3], europe, north-america. asia. oceania, south-america and time.apple.com in that order. Is it the same in the UK? Thanks, Paul. On checking, mine does exactly the same, and my own local stratum-1 server sometimes ends up with a sigma of "", and is not chosen. I now appreciate what you mean by "chosen" - "selected as the comparison source". As William Arnett says - could do better. Perhaps you and I should remind them about that - they have responded to other requests on mine in the past. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Tue, Aug 5, 2014 at 3:24 AM, David J Taylor wrote: > Seems to work correctly here - my local stratum 1 server is displayed if > it's reachable (i.e. I'm on my local network). In the US it tries [0-3].us.pool and my local address. It chooses the "best" three of those and then it chooses one. The list also shows (in pool.ntp.org) [0-3], europe, north-america. asia. oceania, south-america and time.apple.com in that order. Is it the same in the UK? In March 2013 (it seems longer ago): >ET asynchronously sends an NTP request to each of 4 or 5 hosts. It then >requests additional >samples from each host until it gets enough good samples >from at least one host. It then picks the >host whose times were most >consistent (the lowest "sigma" value in the stats display). Since all >this >is happening asynchronously we may stop before getting a full complement of >responses from >each host. And it may not be the host with the lowest RTT. > >ET was our first app that uses NTP. We have since switched to a different >algorithm for picking >which server to use in our other apps. But so far the >new algorithm hasn't been incorporated into >ET. > >William Arnett >Emerald Sequoia LLC" ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
FWIW, since I downloaded Emerald Time a couple days ago, I have not observed an offset of my iPhone's clock from UTC(NTP) of greater than one second. My carrier is T-Mobile. I'll keep watching to see if it stays this good. Sent from my iPhone ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
From: Paul This is an acknowledged design flaw on their part. It will only choose a user provided clock if the default pool is unavailable (short or long term). ___ Very helpful chap/bunch at Emerald. Seems to work correctly here - my local stratum 1 server is displayed if it's reachable (i.e. I'm on my local network). Mind you, it was I who asked for the feature! "Choose" sounds like it might be syncing against that clock - it doesn't, of course, just displays the iPad time versus NTP time, whilst showing a big clock in UTC or local time. For my Android phone I use ClockSync, again to read rather than set the clock as my phone isn't rooted. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
ahhh.. I wondered On Mon, Aug 4, 2014 at 7:27 PM, Paul wrote: > On Mon, Aug 4, 2014 at 6:32 PM, Shane Morris > wrote: > > Bill, > > > > I just got Emerald Time for my iPad - quite a great app, considering I > need > > accurate time for things. Is there a website for the app developer? > > http://www.emeraldsequoia.com/ > > On Mon, Aug 4, 2014 at 8:01 PM, Bill Dailey wrote: > > I put my own ntp server in there and was > > frequently disappinted > > This is an acknowledged design flaw on their part. It will only > choose a user provided clock if the default pool is unavailable (short > or long term). > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Doc Bill Dailey KXØO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Mon, Aug 4, 2014 at 6:32 PM, Shane Morris wrote: > Bill, > > I just got Emerald Time for my iPad - quite a great app, considering I need > accurate time for things. Is there a website for the app developer? http://www.emeraldsequoia.com/ On Mon, Aug 4, 2014 at 8:01 PM, Bill Dailey wrote: > I put my own ntp server in there and was > frequently disappinted This is an acknowledged design flaw on their part. It will only choose a user provided clock if the default pool is unavailable (short or long term). ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Mon, Aug 4, 2014 at 2:24 PM, Brian Garrett wrote: > However,they will not alter the phone's internal clock. Yes, Apple does not present an (unpriviledged) iOS API to set the clock. Neither does (current, unpriviledge) Android. That's probably a good thing. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
you would have to dig around and look. I am sure there is. I have played with it for a year or two. I put my own ntp server in there and was frequently disappinted that it would prefer remote servers quite often.. which cant be better than mine. I dont get that but otherwise I like it. Bill On Mon, Aug 4, 2014 at 5:32 PM, Shane Morris wrote: > Bill, > > I just got Emerald Time for my iPad - quite a great app, considering I need > accurate time for things. Is there a website for the app developer? > > Many thanks! > > Shane. > > > On Tue, Aug 5, 2014 at 8:16 AM, Bob Camp wrote: > > > Hi > > > > I *think* it’s even more specific than that. I’ve watched it switch time > > driving down the road in Indiana. As we did zig zags over the time zone > > line, the iPhone quite happily changed displayed time. My guess was that > it > > used GPS location info to decide which side of the line it was on. > > > > Bob > > > > On Aug 4, 2014, at 1:19 PM, Glen Hoag wrote: > > > > > As someone who crosses time zone boundaries with relative frequency, I > > can tell you that the iPhone does indeed set it's time zone > automatically, > > based on information the phone gets from the cellular network. > > > > > > Sent from my iPhone > > > > > >> On Aug 4, 2014, at 11:49, Chris Albertson > > wrote: > > >> > > >>> On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: > > >>> > > >>> Clearly, just using something like NTP directly isn't all that useful > > >>> because you have to know your physical location to know what timezone > > >>> correction to appl > > >> > > >> I'm pretty sure you have to set the time zone that is displayed. It > > >> does not change based on location. Although one col writ an app that > > >> would do that. There are MANY clock apps some show multiple time > > >> zones. Interannly the phone uses GMT (offset zero) > > >> > > >> > > >> -- > > >> > > >> Chris Albertson > > >> Redondo Beach, California > > >> ___ > > >> time-nuts mailing list -- time-nuts@febo.com > > >> To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > >> and follow the instructions there. > > > ___ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Doc Bill Dailey KXØO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Bill, I just got Emerald Time for my iPad - quite a great app, considering I need accurate time for things. Is there a website for the app developer? Many thanks! Shane. On Tue, Aug 5, 2014 at 8:16 AM, Bob Camp wrote: > Hi > > I *think* it’s even more specific than that. I’ve watched it switch time > driving down the road in Indiana. As we did zig zags over the time zone > line, the iPhone quite happily changed displayed time. My guess was that it > used GPS location info to decide which side of the line it was on. > > Bob > > On Aug 4, 2014, at 1:19 PM, Glen Hoag wrote: > > > As someone who crosses time zone boundaries with relative frequency, I > can tell you that the iPhone does indeed set it's time zone automatically, > based on information the phone gets from the cellular network. > > > > Sent from my iPhone > > > >> On Aug 4, 2014, at 11:49, Chris Albertson > wrote: > >> > >>> On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: > >>> > >>> Clearly, just using something like NTP directly isn't all that useful > >>> because you have to know your physical location to know what timezone > >>> correction to appl > >> > >> I'm pretty sure you have to set the time zone that is displayed. It > >> does not change based on location. Although one col writ an app that > >> would do that. There are MANY clock apps some show multiple time > >> zones. Interannly the phone uses GMT (offset zero) > >> > >> > >> -- > >> > >> Chris Albertson > >> Redondo Beach, California > >> ___ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
I've heard that people who live near time zone boundaries (very near, like within a mile or two) often have to switch automatic setting off, because the time might be an hour off depending on which tower their phone connects to. the annual switches to and from daylight saving time can cause one-hour discrepancies too. Fortunately, in this case, turning automatic setting off and then turning it back on forces a re-sync, thus supplying your phone with the right time. -Original Message- From: Glen Hoag Sent: Monday, August 04, 2014 10:19 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] How are iPhones' clocks set under LTE? As someone who crosses time zone boundaries with relative frequency, I can tell you that the iPhone does indeed set it's time zone automatically, based on information the phone gets from the cellular network. Sent from my iPhone On Aug 4, 2014, at 11:49, Chris Albertson wrote: On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: Clearly, just using something like NTP directly isn't all that useful because you have to know your physical location to know what timezone correction to appl I'm pretty sure you have to set the time zone that is displayed. It does not change based on location. Although one col writ an app that would do that. There are MANY clock apps some show multiple time zones. Interannly the phone uses GMT (offset zero) -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Emerald Time is a very nifty little app, and yes, I've used it a number of times to check my phone's displayed time. It's often off by more than two seconds but never more than three, so far. There are several other apps that can check the time with NTP, and display it in different formats, some more attractive/useful than others. However,they will not alter the phone's internal clock. I used to think this was due to the communication protocol needing accurate time in the mobile unit, but it's more likely just some kind of legal thing with Apple that they cannot mess with the clock settings (which _maybe_ could be construed as tampering with the OS). Brian -Original Message- From: Bill Dailey Sent: Monday, August 04, 2014 6:09 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] How are iPhones' clocks set under LTE? For informational purposes I will show what I use to compare with my stock Iphone. It is an app called emerald time. Screenshot at: https://www.dropbox.com/s/zt6tjrsylrrtrc3/2014-08-04%2008.06.02.png You can set it up to sync with you own ntp server. I think. You can just spot check it. I have never done a rigorous analysis but it appears to be within 1.5s or better most of the time. Doc Sent from mobile On Aug 4, 2014, at 7:38 AM, BIll Ezell wrote: LTE does support the long-standard NITZ (network information and time zone) service. It's an easy way to find out just where you are without having to change your TZ settings constantly. In fact, if you go to time settings on HTC Android phones, the 'automatic time update(NITZ)' setting turns on NITZ syncing. iPhones also use NITZ, as do most 3G or LTE phones. But, not necessarily for time. NITZ implementation is carrier-optional, although almost all do support it. I know that Vodafone-Austrailia and a handful of other carriers at least at one point didn't support it. Additionally, the standard doesn't specify how accurate the time has to be, and it varies widely across providers. It's usually within a few seconds, but this isn't a high-precision time reference and can be off by minutes. But, a phone can use the timezone information to then localize time from some other time service. An alternative to determine what your physical location location is uses lower-level information such as the ECGI (extended cell group identity) or location information from the MME (Mobile Management Entity). Don't you just love telecom? Everything's an acronym and frequently an acronym^2 or ^3. Anyway, the phone then looks up the physical location from whatever id it uses, then uses a time service to get the actual time, then localizes it based on the physical location. Clearly, just using something like NTP directly isn't all that useful because you have to know your physical location to know what timezone correction to apply. I work on cell infrastructure, mostly 3G and LTE (Ericsson), and it just amazes me that phones work at all. It is incredibly complicated and convoluted. Unlike CDMA (where time distribution was an automatic part of the low-level protocol) I suspect the time displayed on many modern phones is not set by the telephony synchronous protocol but rather by IP-over-Wifi packets. And the packets don't seem to do a very effective job keeping the clock ont he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" and its clock has always been off by at least a minute. There was a few years ago, a very nice article about the effort to repair the clocks in clock towers in many cities. What rang most true to me was "if you visit a town they can't even keep the clock correct, who else knows what else is wrong there?". Tim N3QE -- Bill Ezell -- The day Microsoft makes something that doesn't suck will be the day they make vacuum cleaners. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
You can select the behavior you prefer... Settings>General>Date & Time. You can set it manually or have it set automatically based on your current location. Leaving to "automatic" uses a surprising amount of battery power. On Mon, Aug 4, 2014 at 3:16 PM, Bob Camp wrote: > Hi > > I *think* it’s even more specific than that. I’ve watched it switch time > driving down the road in Indiana. As we did zig zags over the time zone line, > the iPhone quite happily changed displayed time. My guess was that it used > GPS location info to decide which side of the line it was on. > > Bob > > On Aug 4, 2014, at 1:19 PM, Glen Hoag wrote: > >> As someone who crosses time zone boundaries with relative frequency, I can >> tell you that the iPhone does indeed set it's time zone automatically, based >> on information the phone gets from the cellular network. >> >> Sent from my iPhone >> >>> On Aug 4, 2014, at 11:49, Chris Albertson wrote: >>> On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: Clearly, just using something like NTP directly isn't all that useful because you have to know your physical location to know what timezone correction to appl >>> >>> I'm pretty sure you have to set the time zone that is displayed. It >>> does not change based on location. Although one col writ an app that >>> would do that. There are MANY clock apps some show multiple time >>> zones. Interannly the phone uses GMT (offset zero) >>> >>> >>> -- >>> >>> Chris Albertson >>> Redondo Beach, California >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Hi I *think* it’s even more specific than that. I’ve watched it switch time driving down the road in Indiana. As we did zig zags over the time zone line, the iPhone quite happily changed displayed time. My guess was that it used GPS location info to decide which side of the line it was on. Bob On Aug 4, 2014, at 1:19 PM, Glen Hoag wrote: > As someone who crosses time zone boundaries with relative frequency, I can > tell you that the iPhone does indeed set it's time zone automatically, based > on information the phone gets from the cellular network. > > Sent from my iPhone > >> On Aug 4, 2014, at 11:49, Chris Albertson wrote: >> >>> On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: >>> >>> Clearly, just using something like NTP directly isn't all that useful >>> because you have to know your physical location to know what timezone >>> correction to appl >> >> I'm pretty sure you have to set the time zone that is displayed. It >> does not change based on location. Although one col writ an app that >> would do that. There are MANY clock apps some show multiple time >> zones. Interannly the phone uses GMT (offset zero) >> >> >> -- >> >> Chris Albertson >> Redondo Beach, California >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
As someone who crosses time zone boundaries with relative frequency, I can tell you that the iPhone does indeed set it's time zone automatically, based on information the phone gets from the cellular network. Sent from my iPhone > On Aug 4, 2014, at 11:49, Chris Albertson wrote: > >> On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: >> >> Clearly, just using something like NTP directly isn't all that useful >> because you have to know your physical location to know what timezone >> correction to appl > > I'm pretty sure you have to set the time zone that is displayed. It > does not change based on location. Although one col writ an app that > would do that. There are MANY clock apps some show multiple time > zones. Interannly the phone uses GMT (offset zero) > > > -- > > Chris Albertson > Redondo Beach, California > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Mon, Aug 4, 2014 at 6:09 AM, Bill Dailey wrote: > I have never done a rigorous analysis but it appears to be within 1.5s or > better most of the time. That is what to expect. as of IOS 5 they use NTP but they look at the clock drift and use NTP at a polling interval just good enough to keep under 2 seconds of error. Keeping the clock dead-on requires to much battery power. At least this is what I remember reading when IOS 5 came out. They "ration" use of NTP to maintain a maximum error -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Mon, Aug 4, 2014 at 5:38 AM, BIll Ezell wrote: > Clearly, just using something like NTP directly isn't all that useful > because you have to know your physical location to know what timezone > correction to appl I'm pretty sure you have to set the time zone that is displayed. It does not change based on location. Although one col writ an app that would do that. There are MANY clock apps some show multiple time zones. Interannly the phone uses GMT (offset zero) -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
For informational purposes I will show what I use to compare with my stock Iphone. It is an app called emerald time. Screenshot at: https://www.dropbox.com/s/zt6tjrsylrrtrc3/2014-08-04%2008.06.02.png You can set it up to sync with you own ntp server. I think. You can just spot check it. I have never done a rigorous analysis but it appears to be within 1.5s or better most of the time. Doc Sent from mobile > On Aug 4, 2014, at 7:38 AM, BIll Ezell wrote: > > LTE does support the long-standard NITZ (network information and time zone) > service. It's an easy way to find out just where you are without having to > change your TZ settings constantly. In fact, if you go to time settings on > HTC Android phones, the 'automatic time update(NITZ)' setting turns on NITZ > syncing. iPhones also use NITZ, as do most 3G or LTE phones. But, not > necessarily for time. > > NITZ implementation is carrier-optional, although almost all do support it. I > know that Vodafone-Austrailia and a handful of other carriers at least at one > point didn't support it. Additionally, the standard doesn't specify how > accurate the time has to be, and it varies widely across providers. It's > usually within a few seconds, but this isn't a high-precision time reference > and can be off by minutes. But, a phone can use the timezone information to > then localize time from some other time service. > > An alternative to determine what your physical location location is uses > lower-level information such as the ECGI (extended cell group identity) or > location information from the MME (Mobile Management Entity). Don't you just > love telecom? Everything's an acronym and frequently an acronym^2 or ^3. > Anyway, the phone then looks up the physical location from whatever id it > uses, then uses a time service to get the actual time, then localizes it > based on the physical location. > > Clearly, just using something like NTP directly isn't all that useful because > you have to know your physical location to know what timezone correction to > apply. > > I work on cell infrastructure, mostly 3G and LTE (Ericsson), and it just > amazes me that phones work at all. It is incredibly complicated and > convoluted. > >> Unlike CDMA (where time distribution was an automatic part of the >> low-level protocol) I suspect the time displayed on many modern phones is >> not set by the telephony synchronous protocol but rather by IP-over-Wifi >> packets. >> >> And the packets don't seem to do a very effective job keeping the clock >> ont he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" >> and its clock has always been off by at least a minute. >> >> There was a few years ago, a very nice article about the effort to repair >> the clocks in clock towers in many cities. What rang most true to me was >> "if you visit a town they can't even keep the clock correct, who else knows >> what else is wrong there?". >> >> Tim N3QE > > -- > Bill Ezell > -- > The day Microsoft makes something that doesn't suck > will be the day they make vacuum cleaners. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
LTE does support the long-standard NITZ (network information and time zone) service. It's an easy way to find out just where you are without having to change your TZ settings constantly. In fact, if you go to time settings on HTC Android phones, the 'automatic time update(NITZ)' setting turns on NITZ syncing. iPhones also use NITZ, as do most 3G or LTE phones. But, not necessarily for time. NITZ implementation is carrier-optional, although almost all do support it. I know that Vodafone-Austrailia and a handful of other carriers at least at one point didn't support it. Additionally, the standard doesn't specify how accurate the time has to be, and it varies widely across providers. It's usually within a few seconds, but this isn't a high-precision time reference and can be off by minutes. But, a phone can use the timezone information to then localize time from some other time service. An alternative to determine what your physical location location is uses lower-level information such as the ECGI (extended cell group identity) or location information from the MME (Mobile Management Entity). Don't you just love telecom? Everything's an acronym and frequently an acronym^2 or ^3. Anyway, the phone then looks up the physical location from whatever id it uses, then uses a time service to get the actual time, then localizes it based on the physical location. Clearly, just using something like NTP directly isn't all that useful because you have to know your physical location to know what timezone correction to apply. I work on cell infrastructure, mostly 3G and LTE (Ericsson), and it just amazes me that phones work at all. It is incredibly complicated and convoluted. Unlike CDMA (where time distribution was an automatic part of the low-level protocol) I suspect the time displayed on many modern phones is not set by the telephony synchronous protocol but rather by IP-over-Wifi packets. And the packets don't seem to do a very effective job keeping the clock ont he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" and its clock has always been off by at least a minute. There was a few years ago, a very nice article about the effort to repair the clocks in clock towers in many cities. What rang most true to me was "if you visit a town they can't even keep the clock correct, who else knows what else is wrong there?". Tim N3QE -- Bill Ezell -- The day Microsoft makes something that doesn't suck will be the day they make vacuum cleaners. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Well, I seem to remember finding NTP running on my jail broken iPhone. But that was a few years ago. > On Aug 3, 2014, at 17:41, Tim Shoppa wrote: > > Unlike CDMA (where time distribution was an automatic part of the low-level > protocol) I suspect the time displayed on many modern phones is not set by > the telephony synchronous protocol but rather by IP-over-Wifi packets. > > And the packets don't seem to do a very effective job keeping the clock ont > he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" and > its clock has always been off by at least a minute. > > There was a few years ago, a very nice article about the effort to repair > the clocks in clock towers in many cities. What rang most true to me was > "if you visit a town they can't even keep the clock correct, who else knows > what else is wrong there?". > > Tim N3QE > > > On Sun, Aug 3, 2014 at 4:37 PM, Brian Garrett > wrote: > >> Hi all, >> >> First “time”r here. This may not rank up there with your degree of >> time-nuttery, but I haven’t been able to get an answer elsewhere. Recently >> I was discussing the issue of how the different cellular providers set >> their time, and I told him that I’d read that CDMA phones and towers have >> to have their clocks synced to GPS as part of the protocol, whereas GSM >> phones do not, and can theoretically be set to wall time, and thus phones >> on networks using CDMA would have atomic accuracy all the time since what >> they were getting was as good as GPS. >> >> Well, obviously I was pathetically behind the times. Most everybody these >> days including Verizon, which both I and my friend have now, uses LTE , as >> you know. I have looked all over for info as to what LTE’s time-setting >> requirements are, as implemented by Verizon, but I’ve not seen discussions >> of it anywhere. I’ve seen amusing anecdotes over what can happen if your >> Android isn’t set to receive the network’s time, or what can happen to your >> phone’s clock if you live near a time zone boundary, but no discussion of >> how time dissemination is handled in-network. I know my iPhone can be, and >> usually is, 2 or 3 seconds fast or slow when checked against an accurate >> reference clock, so I’m thinking they can just use wall time like GSM did. >> >> Has this been discussed on the list before? I haven’t seen anything in >> the archives, and no-one at Verizon that we of the unwashed masses have >> access to will know the answer Pointers, anyone? >> >> >> Thanks in advance, >> Brian >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Unlike CDMA (where time distribution was an automatic part of the low-level protocol) I suspect the time displayed on many modern phones is not set by the telephony synchronous protocol but rather by IP-over-Wifi packets. And the packets don't seem to do a very effective job keeping the clock ont he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" and its clock has always been off by at least a minute. There was a few years ago, a very nice article about the effort to repair the clocks in clock towers in many cities. What rang most true to me was "if you visit a town they can't even keep the clock correct, who else knows what else is wrong there?". Tim N3QE On Sun, Aug 3, 2014 at 4:37 PM, Brian Garrett wrote: > Hi all, > > First “time”r here. This may not rank up there with your degree of > time-nuttery, but I haven’t been able to get an answer elsewhere. Recently > I was discussing the issue of how the different cellular providers set > their time, and I told him that I’d read that CDMA phones and towers have > to have their clocks synced to GPS as part of the protocol, whereas GSM > phones do not, and can theoretically be set to wall time, and thus phones > on networks using CDMA would have atomic accuracy all the time since what > they were getting was as good as GPS. > > Well, obviously I was pathetically behind the times. Most everybody these > days including Verizon, which both I and my friend have now, uses LTE , as > you know. I have looked all over for info as to what LTE’s time-setting > requirements are, as implemented by Verizon, but I’ve not seen discussions > of it anywhere. I’ve seen amusing anecdotes over what can happen if your > Android isn’t set to receive the network’s time, or what can happen to your > phone’s clock if you live near a time zone boundary, but no discussion of > how time dissemination is handled in-network. I know my iPhone can be, and > usually is, 2 or 3 seconds fast or slow when checked against an accurate > reference clock, so I’m thinking they can just use wall time like GSM did. > > Has this been discussed on the list before? I haven’t seen anything in > the archives, and no-one at Verizon that we of the unwashed masses have > access to will know the answer Pointers, anyone? > > > Thanks in advance, > Brian > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
IOS is getting the time using the IP network which is above the CDMA or WiFi level. It polls an NTP server just frequently enough to keep the system clock to within "a few seconds" of correct time. I could run the full NTP but doesn't because that would drain the battery to fast. Background tasks mean the CPU can't go into sleep mode. The phone has the GPS receiver too and I'm a little surprised they don't get the time from GPS. But it is all about battery life and there is no need to run the GPS if the phone is not moving. On Sun, Aug 3, 2014 at 1:37 PM, Brian Garrett wrote: > Hi all, > > First “time”r here. This may not rank up there with your degree of > time-nuttery, but I haven’t been able to get an answer elsewhere. Recently I > was discussing the issue of how the different cellular providers set their > time, and I told him that I’d read that CDMA phones and towers have to have > their clocks synced to GPS as part of the protocol, -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
Here's the article and the quote. Very appropriate for time-nuts: http://www.washingtonpost.com/lifestyle/style/for-public-clocks-a-time-warp/2011/10/25/gIQAXOZ5jM_story.html "If the clocks are right — on churches and in classrooms, on stores and in bars — they tell us that things are in order, say clock advocates such as Bernardin. They tell us that people are paying attention. If a clock is wrong, maybe everything else is, too." On Sun, Aug 3, 2014 at 5:41 PM, Tim Shoppa wrote: > Unlike CDMA (where time distribution was an automatic part of the > low-level protocol) I suspect the time displayed on many modern phones is > not set by the telephony synchronous protocol but rather by IP-over-Wifi > packets. > > And the packets don't seem to do a very effective job keeping the clock > ont he phone correct. My employer gave me a Nokia Lumia 630 "Windows Phone" > and its clock has always been off by at least a minute. > > There was a few years ago, a very nice article about the effort to repair > the clocks in clock towers in many cities. What rang most true to me was > "if you visit a town they can't even keep the clock correct, who else knows > what else is wrong there?". > > Tim N3QE > > > On Sun, Aug 3, 2014 at 4:37 PM, Brian Garrett > wrote: > >> Hi all, >> >> First “time”r here. This may not rank up there with your degree of >> time-nuttery, but I haven’t been able to get an answer elsewhere. Recently >> I was discussing the issue of how the different cellular providers set >> their time, and I told him that I’d read that CDMA phones and towers have >> to have their clocks synced to GPS as part of the protocol, whereas GSM >> phones do not, and can theoretically be set to wall time, and thus phones >> on networks using CDMA would have atomic accuracy all the time since what >> they were getting was as good as GPS. >> >> Well, obviously I was pathetically behind the times. Most everybody >> these days including Verizon, which both I and my friend have now, uses LTE >> , as you know. I have looked all over for info as to what LTE’s >> time-setting requirements are, as implemented by Verizon, but I’ve not seen >> discussions of it anywhere. I’ve seen amusing anecdotes over what can >> happen if your Android isn’t set to receive the network’s time, or what can >> happen to your phone’s clock if you live near a time zone boundary, but no >> discussion of how time dissemination is handled in-network. I know my >> iPhone can be, and usually is, 2 or 3 seconds fast or slow when checked >> against an accurate reference clock, so I’m thinking they can just use wall >> time like GSM did. >> >> Has this been discussed on the list before? I haven’t seen anything in >> the archives, and no-one at Verizon that we of the unwashed masses have >> access to will know the answer Pointers, anyone? >> >> >> Thanks in advance, >> Brian >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How are iPhones' clocks set under LTE?
On Sun, Aug 3, 2014 at 4:37 PM, Brian Garrett wrote: > Has this been discussed on the list before? I think so, but google iOS NTP which apparently is what's used to periodically set the clock (at large intervals) but not to discipline it. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] How are iPhones' clocks set under LTE?
Hi all, First “time”r here. This may not rank up there with your degree of time-nuttery, but I haven’t been able to get an answer elsewhere. Recently I was discussing the issue of how the different cellular providers set their time, and I told him that I’d read that CDMA phones and towers have to have their clocks synced to GPS as part of the protocol, whereas GSM phones do not, and can theoretically be set to wall time, and thus phones on networks using CDMA would have atomic accuracy all the time since what they were getting was as good as GPS. Well, obviously I was pathetically behind the times. Most everybody these days including Verizon, which both I and my friend have now, uses LTE , as you know. I have looked all over for info as to what LTE’s time-setting requirements are, as implemented by Verizon, but I’ve not seen discussions of it anywhere. I’ve seen amusing anecdotes over what can happen if your Android isn’t set to receive the network’s time, or what can happen to your phone’s clock if you live near a time zone boundary, but no discussion of how time dissemination is handled in-network. I know my iPhone can be, and usually is, 2 or 3 seconds fast or slow when checked against an accurate reference clock, so I’m thinking they can just use wall time like GSM did. Has this been discussed on the list before? I haven’t seen anything in the archives, and no-one at Verizon that we of the unwashed masses have access to will know the answer Pointers, anyone? Thanks in advance, Brian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
