| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
25 Mar 2005 12:33:54 PM |
| Object: |
How does Atomic Clock sync over ethernet? |
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
.
|
|
| User: "George Dishman" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
25 Mar 2005 01:12:58 PM |
|
|
<perfb@yahoo.com> wrote in message
news:1111775634.301745.37690@z14g2000cwz.googlegroups.com...
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
Possibly NTP or SNTP but you're asking in the wrong
groups, these are for discussion of astronomy and
physics.
http://www.eecis.udel.edu/~mills/database/rfc/rfc2030.txt
More info:
http://www.ntp.org/
George
.
|
|
|
| User: "Randy Poe" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
25 Mar 2005 01:26:15 PM |
|
|
George Dishman wrote:
<perfb@yahoo.com> wrote in message
news:1111775634.301745.37690@z14g2000cwz.googlegroups.com...
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to
nearest
second? Anyone know the algorithm used?
http://www.ntp.org/
Following that link took me eventually to here:
http://www.eecis.udel.edu/~mills/ntp.html
http://www.eecis.udel.edu/~mills/database/brief/overview/overview.pdf
Short answer seems to be: Messages from multiple
time servers, various compensation algorithms, and input
from GPS time services at many locations. So it's not
all coming from Boulder, CO.
- Randy
.
|
|
|
|
|
| User: "George Dishman" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
25 Mar 2005 01:07:39 PM |
|
|
<perfb@yahoo.com> wrote in message
news:1111775634.301745.37690@z14g2000cwz.googlegroups.com...
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
Possibly NTP but you're asking in the wrong
groups, these are for discussion of astronomy
and physics.
For info on NTP you might start here:
http://www.ntp.org/
George
.
|
|
|
|
| User: "T" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
02 Apr 2005 05:11:57 AM |
|
|
wrote:
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
Before I read the other replies, and strictly off the top of my head I
would think computer A & B would 'ping'* each other a few times to get
the lag time established (averaged) and then A would send B the time,
adjusted for the trouble getting through the routers and wire along the way.
Dems me thinks.
TBerk
*In this context ping refers to a command sent from one device to
another with a corresponding reply; "are you there?, Yes I am, and it
took x amount of milliseconds to get your answer..."
Think of it like those sonar pings in the submarine biz.
.
|
|
|
| User: "George Dishman" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
02 Apr 2005 05:46:06 AM |
|
|
"T" <tberk@sbcglobal.net> wrote in message
news:16v3e.8322$V62.7930@newssvr14.news.prodigy.com...
perfb@yahoo.com wrote:
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
Before I read the other replies, and strictly off the top of my head I
would think computer A & B would 'ping'* each other a few times to get the
lag time established (averaged) and then A would send B the time, adjusted
for the trouble getting through the routers and wire along the way.
Dems me thinks.
TBerk
*In this context ping refers to a command sent from one device to another
with a corresponding reply; "are you there?, Yes I am, and it took x
amount of milliseconds to get your answer..."
Think of it like those sonar pings in the submarine biz.
If you add the current timestamp to the message, you
are getting close. This explains in a lot more detail:
http://www.eecis.udel.edu/~mills/database/brief/arch/arch.pdf
George
.
|
|
|
| User: "sean" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
03 Apr 2005 07:15:10 AM |
|
|
"George Dishman" <george@briar.demon.co.uk> wrote in message news:<d2m0gb$jr9$1@news.freedom2surf.net>...
"T" <tberk@sbcglobal.net> wrote in message
news:16v3e.8322$V62.7930@newssvr14.news.prodigy.com...
perfb@yahoo.com wrote:
wondering how the PC 'Atomic Clock' sync utility pgm from
worldtimeserver.com works? How can it sync over the ethernet when
xmit/rcv times are random variables? Or, can it only sync to nearest
second? Anyone know the algorithm used?
Before I read the other replies, and strictly off the top of my head I
would think computer A & B would 'ping'* each other a few times to get the
lag time established (averaged) and then A would send B the time, adjusted
for the trouble getting through the routers and wire along the way.
Dems me thinks.
TBerk
*In this context ping refers to a command sent from one device to another
with a corresponding reply; "are you there?, Yes I am, and it took x
amount of milliseconds to get your answer..."
Think of it like those sonar pings in the submarine biz.
If you add the current timestamp to the message, you
are getting close. This explains in a lot more detail:
http://www.eecis.udel.edu/~mills/database/brief/arch/arch.pdf
George
Hi
This stuff is way beyond me technically although I have downloaded the
paper
but I have had a idea for a while that the perfect sort of privacy
encryption could be based on how long it takes the message from your
home pc to the bank
that would supply a time amount that would be used as the encryption
key.
Anyone else trying to tap in would always have a different time path
being at a different physical location. In a nutshell your pc sends a
message to the bank server with a time sent as part of the key. Your
pcs clock would have to be very accurate . Then the banks pc would
measure how long it took and use that as the encryption key and
encrypt the message and send it back to you.
Then your pc would then work out what the time difference is (as long
as you knew the delay time at the banks pc for send/recieve.etc.
Anyways the internet probably makes this not feasable as its always
diferent routes during a message
Sean
.
|
|
|
| User: "" |
|
| Title: Re: How does Atomic Clock sync over ethernet? |
03 Apr 2005 11:54:17 AM |
|
|
In sci.physics sean <jaymoseley@hotmail.com> wrote:
<snip>
Hi
This stuff is way beyond me technically although I have downloaded the
paper
but I have had a idea for a while that the perfect sort of privacy
encryption could be based on how long it takes the message from your
home pc to the bank
that would supply a time amount that would be used as the encryption
key.
Anyone else trying to tap in would always have a different time path
being at a different physical location. In a nutshell your pc sends a
message to the bank server with a time sent as part of the key. Your
pcs clock would have to be very accurate . Then the banks pc would
measure how long it took and use that as the encryption key and
encrypt the message and send it back to you.
Then your pc would then work out what the time difference is (as long
as you knew the delay time at the banks pc for send/recieve.etc.
Anyways the internet probably makes this not feasable as its always
diferent routes during a message
Sean
Nope, usually it is the same route, but it wouldn't work anyway since
the time over the same physical route is normally not a constant either.
--
Jim Pennino
Remove .spam.sux to reply.
.
|
|
|
|
|
|
|
|
Related Articles |
|
|
