Re: [chrony-users] Time synchronisation over a high-latency packet radio network

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If the detector simply needs to be in the field for a few days, you can always
set the rtc just before you put it into the field. It might, or might not hold
reasonable accuracy for a couple of days (they can be out by many PPM
especially if the temperater fluctuates) Let say 20PPM which is a couple of  seconds per
day more or less. You might be lucky and get a better rtc, but it is dubious.

You can set up chrony so that when it comes up it does a jump to the received
time (wherever it finds its server) Especailly if you r accuracy is a a second
that should bring it easily into range.

So, you could plug them in at home get chrony to get them into time sync, and
then put them outthere for a day or so.

William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 ____|____ and Gravity ______|_

On Wed, 8 May 2019, Stuart Longland wrote:

On 8/5/19 10:35 am, Bill Unruh wrote:
Doable, and I've made future provision for it, but as stated, I'm trying
to keep costs down.  If more hardware is the answer, my first stop will
be for a battery-powered RTC rather than a GPS.

really cheap rtc will have trouble keeping 1 sec accuracy for any length of
time, especially if your device is subject to temperature variations (
it would seem yours will).

Probably, the real advantage with having an RTC is that while it might
drift by a few minutes whilst in storage… it's much better than the
"stock RTC" in the PocketBeagle, which at present is about 3 years out.

These will be brought out of storage, programmed with a call-sign and a
location, used over 3 or 4 days, then put away again for a few months
until the next such event comes along.

This weekend just gone was the first time we used this system, the next
time where we'll likely use it will be in July.  It really just needs to
be able to hold the time for a day whilst un-powered so that `chronyd`
has a small offset to adjust, not a huge one.

Stuart Longland (aka Redhatter, VK4MSL)

I haven't lost my mind...'s backed up on a tape somewhere.

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