Re: [gpsd-dev] [PATCH] Hal Murray's explanations of how ntpd drift works

[Andy Walls]

On Mon, 2013-11-04 at 11:59 +0800, Sanjeev Gupta wrote:


> diff --git a/www/gpsd-time-service-howto.txt b/www/gpsd-time-service-howto.txt
> index 7aa250f..d32c8b7 100644
> --- a/www/gpsd-time-service-howto.txt
> +++ b/www/gpsd-time-service-howto.txt

> +If you turn on logging for loopstats, that will record both offset, drift,
> +and the polling interval  It's easy to feed to gnuplot, see the sample
> +scripts provided with this file *FIX-ME*
> +

The gnuplot commands for the loopstats file are here:

http://lists.gnu.org/archive/html/gpsd-dev/2013-10/msg00152.html

Offset
   gnuplot> plot    "loopstats" using ($2):($3) with lines 1

Offset with jitter as errorbars
   gnuplot> replot  "loopstats" using ($2):($3):($5) with yerrorbars 2

Frequency offset
   gnuplot> plot    "loopstats" using ($2):($4) with lines 1

Frequency offset with frequency jitter as errorbars
   gnuplot> replot  "loopstats" using ($2):($4):($6) with yerrorbars 2

Regards,
Andy