[time-nuts] looking for low-power system for gps ntp timekeeping NANOSG20

[Mark C. Stephens]

You could also try questions at lists.ntp.org.

The developers etc hang out on that list.
There are a lot of helpful experts on NTP there.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Hal Murray
Sent: Thursday, 4 July 2013 8:34 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] looking for low-power system for gps ntp timekeeping NANOSG20

> It is a garmin 18x lvc.

That's pretty vanilla.  It really should work.  I won't be surprised if the NMEA is off by hundreds of ms and/or has 100 ms of wander, but the PPS should work.

Would you please try ntpd's NMEA driver, preferably from the latest ntp-dev
  http://support.ntp.org/bin/view/Main/SoftwareDownloads
The PPS code used by ntpd is different from gpsd.

If that doesn't work we should try to fix it.


>> rather than ntpd's NMEA driver?
> Oh for convenience. I need to patch ntpd to use linux pps (afaik) and 
> on other systems I successfully run gpsd with ntpd (read: low jitter).

Were any of those systems ARM?

---------

One possibility is that the CPU is getting turned off when idle to save power.  If that includes the stuff normally used for timekeeping, things could get screwed up when it gets turned back on.  It has to reset the time, probably getting it from the RTC.


Can you measure the power when idle?  (kill off as much as possible, things like ntpd)  If that's suspiciously low that might be the problem.

Can you keep it busy?  If nothing else, "while true; do true; done"


--
These are my opinions.  I hate spam.



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