[LinuxPPS] thermostated 14.31818 MHz

[Remco den Besten]

In order to minimise the temperature dependency of my system clock I made a 
thermostate with an uA723,
and soldered it on the 14.31818 MHz reference crystal of the system clock 
PLL.

The temperature of the thermostate converges to approx. 50 degr C and the 
results are really good for such a simple
solution. My jitter decreased with an order (approx 10 times). With FreeBSD 
I have 'pps stabilities' of
0.001 - 0.003 ppm, whereas 0.020 - 0.050 ppm was observed without the 
thermostate.
The PLL offset remains within +/- 1 usec most of the time for my ntp server 
ntp.remco.org.

For graphs: see http://remco.org/difference.php

Remco