Max Demian wrote:

> My smartphone shows the time and it looks accurate, but how do I know
> this is from the GPS satellites rather than synchronised via the
> internet or cellphone system?

If a phone has GPS it *could* get time from satellites, but that might
take a lot of time and energy, far more likely the phone will use the
time information sent by the network* instead.

[*] Sending the date/time/timezone is optional for the network, and it's
allowed to have an accuracy in the order of minutes, but I generally
find it's accurate when compared to GPS/MSF master clocks.

In message <l4a9crF5trqU1@mid.individual.net> at Thu, 29 Feb 2024
02:44:42, Andy Burns <usenet@andyburns.uk> writes
>Max Demian wrote:
>
>> My smartphone shows the time and it looks accurate, but how do I know
>>this is from the GPS satellites rather than synchronised via the
>>internet or cellphone system?
>
>If a phone has GPS it *could* get time from satellites, but that might
>take a lot of time and energy, far more likely the phone will use the
>time information sent by the network* instead.
>
I think a lot of 'phones with a GPS receiver built in have the ability
to turn it off (to save battery I think is the main reason - it's
receive-only, so not a privacy issue directly [though depending on the
local laws in your country it may be interrogatable for where you are]);
I would assume that, if the GPS receiver is on, any time the 'phone
displays is from the GPS.
>
>
>[*] Sending the date/time/timezone is optional for the network, and
>it's allowed to have an accuracy in the order of minutes, but I
>generally find it's accurate when compared to GPS/MSF master clocks.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

I finally got my head together, and my body fell apart.

tony sayer <tony@bancom.co.uk> wrote:
> In article <l48p8jFtj3iU1@mid.individual.net>, Mark Carver
> <mark@invalid.com> scribeth thus
>> On 28/02/2024 12:17, Clive Page wrote:
>>> On 13/02/2024 19:17, Brian Gaff wrote:
>>>> Yes well they were stopped some time back and I think are generated by
>>>> the
>>>> bbc themselves with a countdown up to them to aid program producers. So I
>>>> wonder if there was some way that the delay could be accounted for on the
>>>> different media delivery systems. I'd imagine if a sat were involved it
>>>> would be the longest delay. However D
>>>> aB and internet can be worse sometimes but it seems to vary.
>>>>   Brian
>>>
>>> The programme which prompted this thread was, I thought, not really very
>>> good, and almost totally lacking in technical detail.   Like nearly all
>>> BBC programmes it was, I guess, produced by graduates in "media studies"
>>> or something like that.
>>>
>>> About the only detail that was new to me was the claim than at midnight
>>> on a date when a leap second was introduced there would be 7 pips.   But
>>> I don't know of any BBC programme that uses pips at midnight - it always
>>> seems to be the chimes of Big Ben.
>>>
>>> There was nothing about this in the programme, but I'm vaguely remember
>>> hearing many years ago that the BBC used to adjust the timing of the
>>> pips so that a typical listener in the home counties, say 50 km from a
>>> London area transmitter like Wrotham, would get the most accurate
>>> signal.  Anyone living nearer the transmitter than that would get a time
>>> signal a fraction of a millisecond early, those in more distant parts of
>>> the UK would necessarily get it a few milliseconds late, but there
>>> really wasn't much they could do about that at reasonable cost.   Does
>>> anyone else remember that or is my memory playing tricks?
>>>
>>>
>> A far more significant factor, is how far away you are from the radio's
>> loudspeaker !
>
> A far more important factor is how many females there are there who have
> clocks from five to ten minutes fast, or slow even, known that!..
>
> If you want it "that" accurate Rubidium standards are on fleabay from
> time to time;!..
>

Rubidium standards don’t tell the time.

Andy Burns <usenet@andyburns.uk> wrote:
> Max Demian wrote:
>
>> My smartphone shows the time and it looks accurate, but how do I know
>> this is from the GPS satellites rather than synchronised via the
>> internet or cellphone system?
>
> If a phone has GPS it *could* get time from satellites, but that might
> take a lot of time and energy, far more likely the phone will use the
> time information sent by the network* instead.
>
>
>
> [*] Sending the date/time/timezone is optional for the network, and it's
> allowed to have an accuracy in the order of minutes, but I generally
> find it's accurate when compared to GPS/MSF master clocks.
>

A phone isn’t going to get GPS time indoors. I imagine the cellular
networks have very accurate time these days. It’s quite hard not to, as the
easy way is to use NTP within the core. Mind you, I’ve noticed an
increasing number of cell sites sporting GPS antennas, so there must be a
need now either for very accurate time or perhaps they are being used as a
frequency standard (or both).

On 29/02/2024 07:50, Tweed wrote:
> A phone isn’t going to get GPS time indoors. I imagine the cellular
> networks have very accurate time these days. It’s quite hard not to, as the
> easy way is to use NTP within the core. Mind you, I’ve noticed an
> increasing number of cell sites sporting GPS antennas, so there must be a
> need now either for very accurate time or perhaps they are being used as a
> frequency standard (or both).

Proper GPS receivers indicate whether they are receiving a sign and
usually how long since they last updated.

I have never seen a mobile phone indicate when it last updated.

On 29/02/2024 00:31, tony sayer wrote:
> A far more important factor is how many females there are there who have
> clocks from five to ten minutes fast, or slow even, known that!..

I have known many men that do the same.

Tweed wrote:
> A phone isn’t going to get GPS time indoors.
Mine happily sees 20-30 satellites indoors (from multiple constellations)
> I imagine the cellular
> networks have very accurate time these days.
I wasn't suggesting they didn't provide accurate time, just that the GSM
specs don't require them to provide it at all, or require it to be accurate.
> It’s quite hard not to, as the
> easy way is to use NTP within the core. Mind you, I’ve noticed an
> increasing number of cell sites sporting GPS antennas, so there must be a
> need now either for very accurate time or perhaps they are being used as a
> frequency standard (or both).

Andy Burns <usenet@andyburns.uk> wrote:
> Tweed wrote:
>
>> A phone isn’t going to get GPS time indoors.
>
> Mine happily sees 20-30 satellites indoors (from multiple constellations)
>
You aren’t properly indoors :)

JMB99 wrote:

> Proper GPS receivers indicate whether they are receiving a sign and
> usually how long since they last updated.
>
> I have never seen a mobile phone indicate when it last updated.

GPS Status app shows time since last fix.

On 29/02/2024 02:44, Andy Burns wrote:
> Max Demian wrote:
>
>> My smartphone shows the time and it looks accurate, but how do I know
>> this is from the GPS satellites rather than synchronised via the
>> internet or cellphone system?
>
> If a phone has GPS it *could* get time from satellites, but that might
> take a lot of time and energy, far more likely the phone will use the
> time information sent by the network* instead.
>
Depending on the accuracy of the internal clock and the precision
required, it should be possible to periodically check the GPS time and
update the internal clock. Once an hour would be generous, once a day
sufficient.

As I use my phone for navigation, the GPSreceiver is frequemntlyive anyway.

>
> [*] Sending the date/time/timezone is optional for the network, and it's
> allowed to have an accuracy in the order of minutes, but I generally
> find it's accurate when compared to GPS/MSF master clocks.

I got the impression that each data packet contained an origination and
time code to make assembly easier when packets are received out of order
due to factors such as base station switching?

--
Tciao for Now!

John.

John Williamson wrote:

> Andy Burns wrote:
>
>> Sending the date/time/timezone is optional for the network, and it's
>> allowed to have an accuracy in the order of minutes, but I generally
>> find it's accurate when compared to GPS/MSF master clocks.
>
> I got the impression that each data packet contained an origination and
> time code to make assembly easier when packets are received out of order
> due to factors such as base station switching?

That's a different "network clock" not an absolute time as in UTC+/-TZ

The delta between base-station clocks is used when moving from cell-to-cell.

Andy Burns <usenet@andyburns.uk> wrote:
> John Williamson wrote:
>
>> Andy Burns wrote:
>>
>>> Sending the date/time/timezone is optional for the network, and it's
>>> allowed to have an accuracy in the order of minutes, but I generally
>>> find it's accurate when compared to GPS/MSF master clocks.
>>
>> I got the impression that each data packet contained an origination and
>> time code to make assembly easier when packets are received out of order
>> due to factors such as base station switching?
>
> That's a different "network clock" not an absolute time as in UTC+/-TZ
>
> The delta between base-station clocks is used when moving from cell-to-cell.
>
>
>

https://time.is/

time.is is an interesting website. Claimed accuracy:

Time.is is synchronized with an atomic clock - the most accurate time
source in the world. The displayed time will normally have a precision of
0.02-0.10 seconds. The precision depends on your internet connection and
how busy your computer is.

It also measures the delta between what it thinks the time is and your
device’s system time.
My iPhone: 0.105 seconds, my iPad 0.126 seconds.

On 29/02/2024 10:55, Tweed wrote:

> https://time.is/
>
> time.is is an interesting website. Claimed accuracy:
>
> Time.is is synchronized with an atomic clock - the most accurate time
> source in the world. The displayed time will normally have a precision of
> 0.02-0.10 seconds. The precision depends on your internet connection and
> how busy your computer is.
>
> It also measures the delta between what it thinks the time is and your
> device’s system time.
> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>
It tells me that mine is 0.028 seconds out, but is not clear whether it
takes into account the ping time when calculating it.

Ping times of time.is from here ranged between 28 and 42 milliseconds.

--
Tciao for Now!

John.

John Williamson <johnwilliamson@btinternet.com> wrote:
> On 29/02/2024 10:55, Tweed wrote:
>
>> https://time.is/
>>
>> time.is is an interesting website. Claimed accuracy:
>>
>> Time.is is synchronized with an atomic clock - the most accurate time
>> source in the world. The displayed time will normally have a precision of
>> 0.02-0.10 seconds. The precision depends on your internet connection and
>> how busy your computer is.
>>
>> It also measures the delta between what it thinks the time is and your
>> device’s system time.
>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>>
> It tells me that mine is 0.028 seconds out, but is not clear whether it
> takes into account the ping time when calculating it.
>
> Ping times of time.is from here ranged between 28 and 42 milliseconds.
>

I’m assuming the site is using the ntp protocols to transmit the time.
Those protocols are able to compensate for the link delay.

On 29/02/2024 10:55, Tweed wrote:
> Andy Burns <usenet@andyburns.uk> wrote:
>> John Williamson wrote:
>>
>>> Andy Burns wrote:
>>>
>>>> Sending the date/time/timezone is optional for the network, and it's
>>>> allowed to have an accuracy in the order of minutes, but I generally
>>>> find it's accurate when compared to GPS/MSF master clocks.
>>>
>>> I got the impression that each data packet contained an origination and
>>> time code to make assembly easier when packets are received out of order
>>> due to factors such as base station switching?
>>
>> That's a different "network clock" not an absolute time as in UTC+/-TZ
>>
>> The delta between base-station clocks is used when moving from cell-to-cell.
>>
>>
>>
>
> https://time.is/
>
> time.is is an interesting website. Claimed accuracy:
>
> Time.is is synchronized with an atomic clock - the most accurate time
> source in the world. The displayed time will normally have a precision of
> 0.02-0.10 seconds. The precision depends on your internet connection and
> how busy your computer is.
>
> It also measures the delta between what it thinks the time is and your
> device’s system time.
> My iPhone: 0.105 seconds, my iPad 0.126 seconds.

How does it know where you are? I don't use my home location at any
time, and often applications assume I'm in Rochdale (as my ISP is Zen,
who are based in Rochdale). I'm actually about 250 miles away.

Time.is reports:
"Your time is exact!
The difference from Time.is was +0.001 seconds (±0.070 seconds).
Time in Liverpool, United Kingdom now:
11:26:31"

Why Liverpool, when it's about 40 miles from Rochdale (and,
incidentally, not in the direction I live)?

--

Jeff

Jeff Layman <Jeff@invalid.invalid> wrote:
> On 29/02/2024 10:55, Tweed wrote:
>> Andy Burns <usenet@andyburns.uk> wrote:
>>> John Williamson wrote:
>>>
>>>> Andy Burns wrote:
>>>>
>>>>> Sending the date/time/timezone is optional for the network, and it's
>>>>> allowed to have an accuracy in the order of minutes, but I generally
>>>>> find it's accurate when compared to GPS/MSF master clocks.
>>>>
>>>> I got the impression that each data packet contained an origination and
>>>> time code to make assembly easier when packets are received out of order
>>>> due to factors such as base station switching?
>>>
>>> That's a different "network clock" not an absolute time as in UTC+/-TZ
>>>
>>> The delta between base-station clocks is used when moving from cell-to-cell.
>>>
>>>
>>>
>>
>> https://time.is/
>>
>> time.is is an interesting website. Claimed accuracy:
>>
>> Time.is is synchronized with an atomic clock - the most accurate time
>> source in the world. The displayed time will normally have a precision of
>> 0.02-0.10 seconds. The precision depends on your internet connection and
>> how busy your computer is.
>>
>> It also measures the delta between what it thinks the time is and your
>> device’s system time.
>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>
> How does it know where you are? I don't use my home location at any
> time, and often applications assume I'm in Rochdale (as my ISP is Zen,
> who are based in Rochdale). I'm actually about 250 miles away.
>
> Time.is reports:
> "Your time is exact!
> The difference from Time.is was +0.001 seconds (±0.070 seconds).
> Time in Liverpool, United Kingdom now:
> 11:26:31"
>
> Why Liverpool, when it's about 40 miles from Rochdale (and,
> incidentally, not in the direction I live)?
>

It uses geolocation of your IP address. Geolocation is hit and miss at the
best of times. I’m geolocated to the headquarters of my niche ISP. When I
was on Virgin Media I seemed to move around the country as VM moved and
traded blocks of IP addresses.

https://www.geolocation.com/en_us amongst many similar sites will return
where “they” think you are.

On 29/02/2024 00:31, tony sayer wrote:
> In article <l48p8jFtj3iU1@mid.individual.net>, Mark Carver
> <mark@invalid.com> scribeth thus
>> On 28/02/2024 12:17, Clive Page wrote:
>>> On 13/02/2024 19:17, Brian Gaff wrote:
>>>> Yes well they were stopped some time back and I think are generated by
>>>> the
>>>> bbc themselves with a countdown up to them to aid program producers. So I
>>>> wonder if there was some way that the delay could be accounted for on the
>>>> different media delivery systems. I'd imagine if a sat were involved it
>>>> would be the longest delay. However D
>>>> aB and internet can be worse sometimes but it seems to vary.
>>>>   Brian
>>>
>>> The programme which prompted this thread was, I thought, not really very
>>> good, and almost totally lacking in technical detail.   Like nearly all
>>> BBC programmes it was, I guess, produced by graduates in "media studies"
>>> or something like that.
>>>
>>> About the only detail that was new to me was the claim than at midnight
>>> on a date when a leap second was introduced there would be 7 pips.   But
>>> I don't know of any BBC programme that uses pips at midnight - it always
>>> seems to be the chimes of Big Ben.
>>>
>>> There was nothing about this in the programme, but I'm vaguely remember
>>> hearing many years ago that the BBC used to adjust the timing of the
>>> pips so that a typical listener in the home counties, say 50 km from a
>>> London area transmitter like Wrotham, would get the most accurate
>>> signal.  Anyone living nearer the transmitter than that would get a time
>>> signal a fraction of a millisecond early, those in more distant parts of
>>> the UK would necessarily get it a few milliseconds late, but there
>>> really wasn't much they could do about that at reasonable cost.   Does
>>> anyone else remember that or is my memory playing tricks?
>>>
>>>
>> A far more significant factor, is how far away you are from the radio's
>> loudspeaker !
>
> A far more important factor is how many females there are there who have
> clocks from five to ten minutes fast, or slow even, known that!..

The clock in Mrs C's car gains about 60 seconds a month, it gets reset
every March and October when I do the GMT/BST thing, but she moans on
the morning after that the clock isn't fast any more, and she's confused !

The clock is part of the integrated 'audio, bluetooth etc' unit, WTF it
can't just take a sniff of the DAB or FM clock data I don't know !

My car, uses GPS sniffs to keep the clock spot on, except I still need
to manually adjust the 'hour' for GMT/BST.

In message <urpcvl$dmng$1@dont-email.me> at Thu, 29 Feb 2024 07:50:13,
Tweed <usenet.tweed@gmail.com> writes
[]
>A phone isn’t going to get GPS time indoors. I imagine the cellular
[]
Unless it's going to be indoors for a week or more, though, I'd imagine
its internal clock would keep it close enough for any common need for
knowing the time - certainly any human-involved, as opposed to
electronic, use. Assuming its GPS receiver is actually turned on when
it's outdoors (or at least within range).
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

half the lies they tell about me aren't true. - Yogi Berra

In message <l4b6qsFaejrU1@mid.individual.net> at Thu, 29 Feb 2024
11:07:08, John Williamson <johnwilliamson@btinternet.com> writes
>On 29/02/2024 10:55, Tweed wrote:
>
>> https://time.is/
>>
>> time.is is an interesting website. Claimed accuracy:
>>
>> Time.is is synchronized with an atomic clock - the most accurate time
>> source in the world. The displayed time will normally have a precision of
>> 0.02-0.10 seconds. The precision depends on your internet connection and
>> how busy your computer is.
>>
>> It also measures the delta between what it thinks the time is and your
>> device’s system time.
>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>>
>It tells me that mine is 0.028 seconds out, but is not clear whether it
>takes into account the ping time when calculating it.
>
>Ping times of time.is from here ranged between 28 and 42 milliseconds.
>
Ping times. When I worked at the BAE SYSTEMS Advanced Technology Centre
(originally Marconi Research Centre), one of their few products (it was
mainly a research centre, but did some manufacture) was something called
the IFMS, intermediate frequency management system. (Dull name, but the
name had become established before we could name it something snappier.)
We sold a few tens of them - I think - to ESA (the European Space
Agency). [It's a rack-mounted thing full of cards - roughly a cube,
IIRR.] One of its functions was to establish to amazing accuracy - I
think metres, which isn't bad when you're talking of something in the
vicinity of Mars - exactly where a space probe is.

Of course, thinking about _when_ that position was established - i. e.
when you asked it, when it replied, or when the reply came back - does
your head in ... (ping times for a Mars probe are quite long!)

We did, I was told, manage to tell ESA that one of their ground stations
wasn't (by a few tens of centimetres) exactly where they thought it was.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

half the lies they tell about me aren't true. - Yogi Berra

On 29/02/2024 11:41, Tweed wrote:
> Jeff Layman <Jeff@invalid.invalid> wrote:
>> On 29/02/2024 10:55, Tweed wrote:
>>> Andy Burns <usenet@andyburns.uk> wrote:
>>>> John Williamson wrote:
>>>>
>>>>> Andy Burns wrote:
>>>>>
>>>>>> Sending the date/time/timezone is optional for the network, and it's
>>>>>> allowed to have an accuracy in the order of minutes, but I generally
>>>>>> find it's accurate when compared to GPS/MSF master clocks.
>>>>>
>>>>> I got the impression that each data packet contained an origination and
>>>>> time code to make assembly easier when packets are received out of order
>>>>> due to factors such as base station switching?
>>>>
>>>> That's a different "network clock" not an absolute time as in UTC+/-TZ
>>>>
>>>> The delta between base-station clocks is used when moving from cell-to-cell.
>>>>
>>>>
>>>>
>>>
>>> https://time.is/
>>>
>>> time.is is an interesting website. Claimed accuracy:
>>>
>>> Time.is is synchronized with an atomic clock - the most accurate time
>>> source in the world. The displayed time will normally have a precision of
>>> 0.02-0.10 seconds. The precision depends on your internet connection and
>>> how busy your computer is.
>>>
>>> It also measures the delta between what it thinks the time is and your
>>> device’s system time.
>>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>>
>> How does it know where you are? I don't use my home location at any
>> time, and often applications assume I'm in Rochdale (as my ISP is Zen,
>> who are based in Rochdale). I'm actually about 250 miles away.
>>
>> Time.is reports:
>> "Your time is exact!
>> The difference from Time.is was +0.001 seconds (±0.070 seconds).
>> Time in Liverpool, United Kingdom now:
>> 11:26:31"
>>
>> Why Liverpool, when it's about 40 miles from Rochdale (and,
>> incidentally, not in the direction I live)?
>>
>
> It uses geolocation of your IP address. Geolocation is hit and miss at the
> best of times. I’m geolocated to the headquarters of my niche ISP. When I
> was on Virgin Media I seemed to move around the country as VM moved and
> traded blocks of IP addresses.

That could be the reason.

> https://www.geolocation.com/en_us amongst many similar sites will return
> where “they” think you are.

I have "location" turned off in my browser's settings, and it's not
going back on, so that site doesn't work.

--

Jeff

Jeff Layman <jeff@invalid.invalid> wrote:
> On 29/02/2024 11:41, Tweed wrote:
>> Jeff Layman <Jeff@invalid.invalid> wrote:
>>> On 29/02/2024 10:55, Tweed wrote:
>>>> Andy Burns <usenet@andyburns.uk> wrote:
>>>>> John Williamson wrote:
>>>>>
>>>>>> Andy Burns wrote:
>>>>>>
>>>>>>> Sending the date/time/timezone is optional for the network, and it's
>>>>>>> allowed to have an accuracy in the order of minutes, but I generally
>>>>>>> find it's accurate when compared to GPS/MSF master clocks.
>>>>>>
>>>>>> I got the impression that each data packet contained an origination and
>>>>>> time code to make assembly easier when packets are received out of order
>>>>>> due to factors such as base station switching?
>>>>>
>>>>> That's a different "network clock" not an absolute time as in UTC+/-TZ
>>>>>
>>>>> The delta between base-station clocks is used when moving from cell-to-cell.
>>>>>
>>>>>
>>>>>
>>>>
>>>> https://time.is/
>>>>
>>>> time.is is an interesting website. Claimed accuracy:
>>>>
>>>> Time.is is synchronized with an atomic clock - the most accurate time
>>>> source in the world. The displayed time will normally have a precision of
>>>> 0.02-0.10 seconds. The precision depends on your internet connection and
>>>> how busy your computer is.
>>>>
>>>> It also measures the delta between what it thinks the time is and your
>>>> device’s system time.
>>>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>>>
>>> How does it know where you are? I don't use my home location at any
>>> time, and often applications assume I'm in Rochdale (as my ISP is Zen,
>>> who are based in Rochdale). I'm actually about 250 miles away.
>>>
>>> Time.is reports:
>>> "Your time is exact!
>>> The difference from Time.is was +0.001 seconds (±0.070 seconds).
>>> Time in Liverpool, United Kingdom now:
>>> 11:26:31"
>>>
>>> Why Liverpool, when it's about 40 miles from Rochdale (and,
>>> incidentally, not in the direction I live)?
>>>
>>
>> It uses geolocation of your IP address. Geolocation is hit and miss at the
>> best of times. I’m geolocated to the headquarters of my niche ISP. When I
>> was on Virgin Media I seemed to move around the country as VM moved and
>> traded blocks of IP addresses.
>
> That could be the reason.
>
>> https://www.geolocation.com/en_us amongst many similar sites will return
>> where “they” think you are.
>
> I have "location" turned off in my browser's settings, and it's not
> going back on, so that site doesn't work.
>

You can decline the invitation to turn on browser location. The site still
works.

On 29/02/2024 03:23, J. P. Gilliver wrote:
> In message <l4a9crF5trqU1@mid.individual.net> at Thu, 29 Feb 2024
> 02:44:42, Andy Burns <usenet@andyburns.uk> writes
>> Max Demian wrote:
>>
>>> My smartphone shows the time and it looks accurate, but how do I know
>>> this is from the GPS satellites rather than synchronised via the
>>> internet or cellphone system?
>>
>> If a phone has GPS it *could* get time from satellites, but that might
>> take a lot of time and energy, far more likely the phone will use the
>> time information sent by the network* instead.
>>
> I think a lot of 'phones with a GPS receiver built in have the ability
> to turn it off (to save battery I think is the main reason - it's
> receive-only, so not a privacy issue directly [though depending on the
> local laws in your country it may be interrogatable for where you are]);
> I would assume that, if the GPS receiver is on, any time the 'phone
> displays is from the GPS.
>>
>>
>> [*] Sending the date/time/timezone is optional for the network, and
>> it's allowed to have an accuracy in the order of minutes, but I
>> generally find it's accurate when compared to GPS/MSF master clocks.

The 'Commander' app on my iphone shows the time accurate to the second
against FM radio.
--
Mike Headon
R69S R850R
IIIc IIIg FT FTn FT2 EOS450D
e-mail: mike dot headon at enn tee ell world dot com

On 29/02/2024 00:31, tony sayer wrote:
> In article <l48p8jFtj3iU1@mid.individual.net>, Mark Carver
> <mark@invalid.com> scribeth thus
>> On 28/02/2024 12:17, Clive Page wrote:
>>> On 13/02/2024 19:17, Brian Gaff wrote:
>>>> Yes well they were stopped some time back and I think are generated by
>>>> the
>>>> bbc themselves with a countdown up to them to aid program producers. So I
>>>> wonder if there was some way that the delay could be accounted for on the
>>>> different media delivery systems. I'd imagine if a sat were involved it
>>>> would be the longest delay. However D
>>>> aB and internet can be worse sometimes but it seems to vary.
>>>>   Brian
>>>
>>> The programme which prompted this thread was, I thought, not really very
>>> good, and almost totally lacking in technical detail.   Like nearly all
>>> BBC programmes it was, I guess, produced by graduates in "media studies"
>>> or something like that.
>>>
>>> About the only detail that was new to me was the claim than at midnight
>>> on a date when a leap second was introduced there would be 7 pips.   But
>>> I don't know of any BBC programme that uses pips at midnight - it always
>>> seems to be the chimes of Big Ben.
>>>
>>> There was nothing about this in the programme, but I'm vaguely remember
>>> hearing many years ago that the BBC used to adjust the timing of the
>>> pips so that a typical listener in the home counties, say 50 km from a
>>> London area transmitter like Wrotham, would get the most accurate
>>> signal.  Anyone living nearer the transmitter than that would get a time
>>> signal a fraction of a millisecond early, those in more distant parts of
>>> the UK would necessarily get it a few milliseconds late, but there
>>> really wasn't much they could do about that at reasonable cost.   Does
>>> anyone else remember that or is my memory playing tricks?
>>>
>>>
>> A far more significant factor, is how far away you are from the radio's
>> loudspeaker !
>
> A far more important factor is how many females there are there who have
> clocks from five to ten minutes fast, or slow even, known that!..
>
> If you want it "that" accurate Rubidium standards are on fleabay from
> time to time;!..
>
They used to say that radio listeners in Australia heard the chime of
Big Ben before someone outdoors in Lambeth!
--
Mike Headon
R69S R850R
IIIc IIIg FT FTn FT2 EOS450D
e-mail: mike dot headon at enn tee ell world dot com

On 29/02/2024 14:35, Tweed wrote:
> Jeff Layman <jeff@invalid.invalid> wrote:
>> On 29/02/2024 11:41, Tweed wrote:
>>> Jeff Layman <Jeff@invalid.invalid> wrote:
>>>> On 29/02/2024 10:55, Tweed wrote:
>>>>> Andy Burns <usenet@andyburns.uk> wrote:
>>>>>> John Williamson wrote:
>>>>>>
>>>>>>> Andy Burns wrote:
>>>>>>>
>>>>>>>> Sending the date/time/timezone is optional for the network, and it's
>>>>>>>> allowed to have an accuracy in the order of minutes, but I generally
>>>>>>>> find it's accurate when compared to GPS/MSF master clocks.
>>>>>>>
>>>>>>> I got the impression that each data packet contained an origination and
>>>>>>> time code to make assembly easier when packets are received out of order
>>>>>>> due to factors such as base station switching?
>>>>>>
>>>>>> That's a different "network clock" not an absolute time as in UTC+/-TZ
>>>>>>
>>>>>> The delta between base-station clocks is used when moving from cell-to-cell.
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>> https://time.is/
>>>>>
>>>>> time.is is an interesting website. Claimed accuracy:
>>>>>
>>>>> Time.is is synchronized with an atomic clock - the most accurate time
>>>>> source in the world. The displayed time will normally have a precision of
>>>>> 0.02-0.10 seconds. The precision depends on your internet connection and
>>>>> how busy your computer is.
>>>>>
>>>>> It also measures the delta between what it thinks the time is and your
>>>>> device’s system time.
>>>>> My iPhone: 0.105 seconds, my iPad 0.126 seconds.
>>>>
>>>> How does it know where you are? I don't use my home location at any
>>>> time, and often applications assume I'm in Rochdale (as my ISP is Zen,
>>>> who are based in Rochdale). I'm actually about 250 miles away.
>>>>
>>>> Time.is reports:
>>>> "Your time is exact!
>>>> The difference from Time.is was +0.001 seconds (±0.070 seconds).
>>>> Time in Liverpool, United Kingdom now:
>>>> 11:26:31"
>>>>
>>>> Why Liverpool, when it's about 40 miles from Rochdale (and,
>>>> incidentally, not in the direction I live)?
>>>>
>>>
>>> It uses geolocation of your IP address. Geolocation is hit and miss at the
>>> best of times. I’m geolocated to the headquarters of my niche ISP. When I
>>> was on Virgin Media I seemed to move around the country as VM moved and
>>> traded blocks of IP addresses.
>>
>> That could be the reason.
>>
>>> https://www.geolocation.com/en_us amongst many similar sites will return
>>> where “they” think you are.
>>
>> I have "location" turned off in my browser's settings, and it's not
>> going back on, so that site doesn't work.
>>
>
> You can decline the invitation to turn on browser location. The site still
> works.

I get a pop-up box if I try:

"www.geolocation.com

User has denied the request for sharing location. Please enable location
sharing in web browser."

What I find odd is that <https://www.iplocation.net/myip> shows my IP
address, and gives its location as Northampton. If that site can detect
it, why can't <https://www.geolocation.com/en_us>?

Out of interest I fed it my IP address as detected by
<https://www.iplocation.net/myip>. It reported it as being at Little
Biencow near Penrith!

--

Jeff

On 29/02/2024 14:59, Mike Headon wrote:
> On 29/02/2024 00:31, tony sayer wrote:
>> A far more important factor is how many females there are there who have
>> clocks from five to ten minutes fast, or slow even, known that!..
>>
>> If you want it "that" accurate Rubidium standards are on fleabay from
>> time to time;!..
>>
> They used to say that radio listeners in Australia heard the chime of
> Big Ben before someone outdoors in Lambeth!

Marginal. If you stand on the South Bank next to Westminster Bridge, the
speed of sound delay is about 750 milliseconds.

Transmission delay to and from geostationary orbit is about half a
second plus landline delay at each end, not forgetting that at least two
satellites are involved due to imitations of coverage. Using landline
all the way is even slower. You may do slightly better using the
Starlink constellation, which are all in very low orbits and can link
with each other, with a ping time to a ground station of about 50 ms.

--
Tciao for Now!

John.