Cell timing error
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
Greg:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
--- Graham / KE9H
==
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
In a prior life we had a CDMA timing receiver for NTP which used VZ for its source
Sent from my iPhone
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com wrote:
Greg:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
--- Graham / KE9H
==
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times very close to 1 min slow. Virgin/sprint is ok. I've never seen this before - usually it's a few s slow.
time-nuts mailing list -- time-nuts@febo.com
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On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for its source
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com wrote:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times very close to 1 min slow. Virgin/sprint is ok. I've never seen this before - usually it's a few s slow.
The time displayed on the phone might not reflect the time from the
network.
AT&T uses UMTS in most areas which is a "self-synchronizing" modulation
scheme. Supposedly one of the selling points is "no dependence on GPS". All
the extra sync channels and sync messaging is a capacity hog, not a very
spectrally efficient standard in my opinion.
About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL
sector/carrier before it starts to fall apart. A big step backwards from
good old CDMA2000 (also just my opinion).
But hey, you can surf the web while you talk on the same device.
-Joe W4WN
----- Original Message -----
From: "Jim Lux" jimlux@earthlink.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error
On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for
its source
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com
wrote:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
The time displayed on the phone might not reflect the time from the
network.
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.
Hi
There are a lot of layers between the base station and the phone it's self when it comes to the time that's displayed. There also are a lot of opportunities for error as each layer is linked together. Often when you see "Verizon" you are actually connected to "Bob's Cell Phone Tower". Bob may or (may not) be very careful about linking all the layers together.
Best bet, use something like an NTP client, that goes around all the network "stuff".
Bob
On Dec 15, 2012, at 5:43 PM, Jim Lux jimlux@earthlink.net wrote:
On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for its source
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com wrote:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times very close to 1 min slow. Virgin/sprint is ok. I've never seen this before - usually it's a few s slow.
The time displayed on the phone might not reflect the time from the network.
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.
I can assure you the GSM shacks have GPS timing in them. I can dig up the photos if you want.
-----Original Message-----
From: "Joseph Orsak" jorsak@nc.rr.com
Sender: time-nuts-bounces@febo.com
Date: Sat, 15 Dec 2012 18:24:20
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Cell timing error
AT&T uses UMTS in most areas which is a "self-synchronizing" modulation
scheme. Supposedly one of the selling points is "no dependence on GPS". All
the extra sync channels and sync messaging is a capacity hog, not a very
spectrally efficient standard in my opinion.
About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL
sector/carrier before it starts to fall apart. A big step backwards from
good old CDMA2000 (also just my opinion).
But hey, you can surf the web while you talk on the same device.
-Joe W4WN
----- Original Message -----
From: "Jim Lux" jimlux@earthlink.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error
On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for
its source
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com
wrote:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
The time displayed on the phone might not reflect the time from the
network.
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.
On 12/16/2012 12:59 AM, lists@lazygranch.com wrote:
I can assure you the GSM shacks have GPS timing in them. I can dig up the photos if you want.
Depens on how the network was built. GSM does not need anything but +/-
50 ppb timing. The PDH backhaul will provide that usually. The time that
the mobile get's comes from the controler, which could be slaved using
NTP... or not. It may not even transfer time, since this is an option
which many but not all operators have enabled.
Cheers,
Magnus
GSM cell sites in the US have GPS because it is required to
support E911 positioning. I'm not sure if it is used for anything
other than this, but it doesn't have to be.
In some other parts of the world it has been considered bad taste
to let the operation of telecommunications infrastructure become
dependent on a facility owned by the US military, so the standards
that are popular there often try to avoid that.
Dennis Ferguson
On 15 Dec, 2012, at 18:59 , lists@lazygranch.com wrote:
I can assure you the GSM shacks have GPS timing in them. I can dig up the photos if you want.
-----Original Message-----
From: "Joseph Orsak" jorsak@nc.rr.com
Sender: time-nuts-bounces@febo.com
Date: Sat, 15 Dec 2012 18:24:20
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Cell timing error
AT&T uses UMTS in most areas which is a "self-synchronizing" modulation
scheme. Supposedly one of the selling points is "no dependence on GPS". All
the extra sync channels and sync messaging is a capacity hog, not a very
spectrally efficient standard in my opinion.
About 85 maximum simultaneous voice calls in a 5Mhz UL / 5 Mhz DL
sector/carrier before it starts to fall apart. A big step backwards from
good old CDMA2000 (also just my opinion).
But hey, you can surf the web while you talk on the same device.
-Joe W4WN
----- Original Message -----
From: "Jim Lux" jimlux@earthlink.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, December 15, 2012 5:43 PM
Subject: Re: [time-nuts] Cell timing error
On 12/15/12 2:16 PM, Scott McGrath wrote:
In a prior life we had a CDMA timing receiver for NTP which used VZ for
its source
On Dec 15, 2012, at 12:18 PM, Graham / KE9H timenut@austin.rr.com
wrote:
You should switch to Verizon.
They are inherently accurate to milliseconds.
Sub micro-seconds inside the base stations.
On 12/15/2012 12:51 PM, Greg Troxel wrote:
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
The time displayed on the phone might not reflect the time from the
network.
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.
Greg Troxel gdt@ir.bbn.com writes:
Date: Sat, 15 Dec 2012 13:51:45 -0500
In central mass, AT&T and tracfone (? carrier) are showing phone times
very close to 1 min slow. Virgin/sprint is ok. I've never seen this
before - usually it's a few s slow.
Thanks for all the comments. Following up from a real keyboard:
The tracfrone was on the AT&T network, per the code on the SIM. So I
think this was just AT&T.
The timing error was resolved sometime later on Saturday.
I realize the phone display time and GSM time are not well connected.
Emerald Time (iPhone program) does NTP and shows the difference
between the time on the unix computer in the phone and NTP peers.
Typically I see values from -0.5s to about 4.5s. Right now it shows
+4.348s (phone computer is 4.348s slow). The phone display switched
to 1849 at about 184907, which I attribute to 4s slow and a slow
update rate of the display.
Based on observing Emerald Time's offset over long periods, I believe
that there is some loose synchronization of the phone cpu to the cell
network, and that the phone free runs until it gets too far off and
then it is stepped to be closer.
On Saturday, Emerald Time was reporting +60.580. The time on my phone
was 1 minute slow and updated around minute boundaries, just one
minute behind.
A tracphone (LG featurephone) showed exactly the same one-minute slow
behavior. So I suspect that something was off in the GSM time
reference. I am not sure if more than one cell site was affected.