PSN-L Email List Message

Subject: RE: Is our quake time correct?
From: "Keith Payea" kpayea@..............
Date: Thu, 22 Dec 2011 08:45:30 -0800


Hello All:

 

First, most GPS receivers do correct for the GPS:UTC leap seconds issue, and
output UTC.  However, it is possible on some of them to change a setting and
get raw GPS time.  Since the offset is 15 seconds, it's pretty easy to check
your receiver.

 

Secondly, most of the "NTP" software toys available for free are really
doing SNTP (Simple Network Time Protocol) which does very little except ask
for the current time once in a while and jam it into your computer's clock.
Real NTP compensates for transmission delays and uses multiple servers as
inputs to a very complex filtering algorithm to remove all kinds of errors.

 

Meinberg offers a full NTP implementation for windows that actually steers
the clock and does all of the filtering.  You can get it here:

 

http://www.meinberg.de/english/sw/ntp.htm

 

I've used it for a few years and it works great.  The time on my data
logging computer stays within a few tens of milliseconds to UTC.

 

I used to work for one of their competitors.

 

                Keith

 

 

From: psnlist-request@.............. [mailto:psnlist-request@...............
On Behalf Of chrisatupw@.......
Sent: Thursday, December 22, 2011 4:32 AM
To: psnlist@..............
Subject: Re: Is our quake time correct?

 

 

Jim Hannon jmhannon@.........
Subject: Re: Is our quake time correct?

Here is a good explanation of the situation.
http://gpsinformation.net/main/gpstime.htm
Basically there should be no problem as the receiver should read the UTC 
offset information and correct. Especially a receiver that has been 
running all along.
 
Hi Jim, 
    It is fine if you get your UTC directly off the satellites, but 
some of us use on-line time servers and there may be a transmission 
delay over the www. AboutTime gives good results, but resetting your 
computer over the www using the link built into Windows can give 
errors of over 2 seconds, from my personal experiences, depending on 
the exact time of day. I compare the NIST web signal with the direct  
MSF Rugby 60 kHz radio signal, which has an accuracy of 20 milli sec.  
    Regards,
    Chris Chapman

Hello All:

 

First, most GPS receivers do correct for the GPS:UTC leap seconds = issue, and output UTC.  However, it is possible on some of them to = change a setting and get raw GPS time.  Since the offset is 15 = seconds, it’s pretty easy to check your = receiver.

 

Secondly, most of the “NTP” software toys available for = free are really doing SNTP (Simple Network Time Protocol) which does = very little except ask for the current time once in a while and jam it = into your computer’s clock.  Real NTP compensates for = transmission delays and uses multiple servers as inputs to a very = complex filtering algorithm to remove all kinds of = errors.

 

Meinberg offers a full NTP implementation for windows that actually = steers the clock and does all of the filtering.  You can get it = here:

 

http://www.meinberg.de= /english/sw/ntp.htm

 

I’ve used it for a few years and it works great.  The time = on my data logging computer stays within a few tens of milliseconds to = UTC.

 

I used to work for one of their = competitors…

 

           &nbs= p;    Keith

 

 

From:= = psnlist-request@.............. [mailto:psnlist-request@............... = On Behalf Of chrisatupw@.......
Sent: Thursday, = December 22, 2011 4:32 AM
To: = psnlist@..............
Subject: Re: Is our quake time = correct?

 

<= o:p> 

J= im Hannon jmhannon@.........
Subject: = Re: Is our quake time correct?

Here is a =
good explanation of the situation.
http://gpsinformation.net/main/gpstime.htm
Basically there should be no problem as the =
receiver should read the UTC 
offset =
information and correct. Especially a receiver that has been =
running all =
along.
 
Hi Jim, 
    It is =
fine if you get your UTC directly off the satellites, but =
some of us use on-line time =
servers and there may be a transmission 
delay over the www. AboutTime =
gives good results, but resetting your 
computer over the www using the =
link built into Windows can give 
errors of over 2 seconds, from my =
personal experiences, depending on 
the exact time of day. I compare =
the NIST web signal with the direct  
MSF Rugby 60 kHz radio signal, =
which has an accuracy of 20 milli sec.  
    Regards,
    Chris =
Chapman

[ Top ] [ Back ] [ Home Page ]