Re: [ntp:questions] Sudden drop in frequency after software update

2009-01-20 Thread Hal Murray
>I've seen a different frequency correction needed after a kernel is >installed. That wouldn't surprise me. The calibration is a combination of the hardware and the software. Somebody could easily fix/tweak the software and change some of the details of the calculations or the timing. The prob

Re: [ntp:questions] Sudden drop in frequency after software update

2009-01-20 Thread Hal Murray
>It would be interesting to know what kernel version those who are having >trouble with unstable drift in Linux are using. I am using kernel >2.6.27.7, and it is very stable, varying no more than 5 PPM, even across >reboots. It should be noted that I rebuilt my kernel with the timer >frequency s

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Unruh
ryad@gmail.com writes: >> >As a conclusion I can use them to estimate the skew (as you suggest >> >"by integrating and so on") over the last period (the period >> >between the last kernel update and now) >> >> I still have absolutely no idea what you are trying to do. >> >Here is what I w

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread ryad . bek
> >As a conclusion I can use them to estimate the skew (as you suggest > >"by integrating and so on") over the last period (the period > >between the last kernel update and now) > > I still have absolutely no idea what you are trying to do. > Here is what I want to do (I have reformulated my i

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Terje Mathisen
Richard B. Gilbert wrote: > Terje Mathisen wrote: >> Running with logging a GPS which isn't used to steer the clock is >> actually much easier and more accurate. >> >> You'll find that you don't need us precision: After a few hours the >> offsets will probably be into the multiple seconds range,

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Unruh
ryad@gmail.com writes: >On Jan 20, 2:00=A0am, Unruh wrote: >> >I want to compare the outputs of an application when this app is fed >> >with GPS input & when it is fed with HW input >> >HW input =3D series of ("HW timestamp" + event) >> >GPS input =3D series of ("GPS timestamps" + event) >>

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Unruh
"Richard B. Gilbert" writes: >Terje Mathisen wrote: >> ryad@gmail.com wrote: >>> On Jan 19, 10:26 pm, Terje Mathisen >>> wrote: ryad@gmail.com wrote: > Hello everybody, > I'm trying to track (offline) the drift of my gps clock relative to my > hw clock (the clock that I

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Richard B. Gilbert
ryad@gmail.com wrote: > On Jan 20, 2:00 am, Unruh wrote: > >>> I want to compare the outputs of an application when this app is fed >>> with GPS input & when it is fed with HW input >>> HW input = series of ("HW timestamp" + event) >>> GPS input = series of ("GPS timestamps" + event) >> So fe

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread Richard B. Gilbert
Terje Mathisen wrote: > ryad@gmail.com wrote: >> On Jan 19, 10:26 pm, Terje Mathisen >> wrote: >>> ryad@gmail.com wrote: Hello everybody, I'm trying to track (offline) the drift of my gps clock relative to my hw clock (the clock that I would have obtained without GPS).

Re: [ntp:questions] Tracking the drift of a GPS clock relative to a HW clock

2009-01-20 Thread ryad . bek
On Jan 20, 2:00 am, Unruh wrote: > >I want to compare the outputs of an application when this app is fed > >with GPS input & when it is fed with HW input > >HW input = series of ("HW timestamp" + event) > >GPS input = series of ("GPS timestamps" + event) > > So feed it with time stamp inputs and