[time-nuts] Warped back to 1993

Hal Murray hmurray at megapathdsl.net
Sun Aug 11 17:32:33 EDT 2013


lists at rtty.us said:
> The issue with the fudge option is that you need to engage it at exactly the
> right point. Put another way, there's a period between it failing and your
> entering a fudge that the NTP server is down.

Yup.  But if you are running along and suddenly your GPS breaks, you might be 
able to fix it by editing a config file and not needing to install any new 
software or wait for the bug to get fixed.

> With a couple lines of auto correct code in there, it would (essentially)
> never fail. If you are running a GPS, you enable the auto-correction and
> forget about it. My guess is that many GPS devices will eventually suffer
> from the wrap around

Agreed.


> The  only way they could avoid it would be some sort of external correction
> (like continuous firmware updates) or a "no reverse" on the year. Both
> approaches have their drawbacks
..

There is another option that may be good-enough for some/many of us.  That is 
a way to tell the GPS unit the date.

If a GPS device knows the rough date, it can get the right answer.

Most GPS units have a battery and 32KHz clock to keep track of the time so 
they can get started (much) quicker on power up: warm start vs cold start.  
This isn't quite "no reverse", but it's pretty close.

1024 weeks is 20 years, so the batteries are probably old by the time this 
gets interesting.  But even an old tired battery might keep a clock ticking 
for a few minutes/hours.  That might cover rearranging cables or a 
not-too-long power outage.

But after the unit has been powered off too long (relative to the battery) or 
after you replace the battery, you need some way to set the date.

My Z3801A has been happy since I told it the date.  I don't know if it has 
been powered off since then.  I should probably try the experiment.



-- 
These are my opinions.  I hate spam.





More information about the time-nuts mailing list