Stratum one autonomy and assumptions about GPS

Hal Murray hmurray at
Thu Aug 25 09:29:54 UTC 2016

There is lots of good stuff there.


It sounds like you are trying to rationalize running without any network 

Even if you do collect lots of data, you can't extrapolate very far from a 
sample of one.

There are many ways to screw up.  Even if you get a lot of data, there will 
be more things to consider.


Firmware will have bugs.  OSes will have bugs.  Software will have bugs.
  I have a unit that occasionally gets off by a second with gpsd.
  (It's the one that starts sending NMEA just before the top of a second.)

The GPS operators may screw up.
A trucker with a jammer may park in front of your house.
Rain/snow may land on your trees.
Somebody will try to use their wonderful modern unit farther from the window 
or deeper in an urban canyon.

Your 10ms error budget may be fine for some applications but others may want 


Actually, for short outages, it may be better to ignore network servers and 
just coast with the current drift setting.  That would be a good experiment.  
That probably depends on the unit dying cleanly rather than sliding off in 
some direction before it gives up.

These are my opinions.  I hate spam.

More information about the devel mailing list