Hi Chris. 

Think I can add a bit of context.

How the devices currently function is the timer for when the next GPS fix attempt occurs starts after the last successful fix. This means if it took the collar several attempts to get a fix due to heavy canopy or other reasons then instead of it being say 2hrs between GPS fixes it might be 2hrs 4mins. A series of fixed could look like:

00:00, 02:04, 04:09, 06:11

And so on. It's a cumulative effect. A situation we've heard where this might be relevant could be a research study tracking an animals activity levels during different points in a day. Say morning, noon and evening. With the current methodology if someone wanted to measure activity levels at 10am daily you couldn't. It would slowly drift later and later.

It's an interesting thought experiment and technical challenge but before we dive into the engineering we wanted to hear people's thoughts on if this is even important to them or the right thing to work on. 

One example that surprised me was even though our devices are capable of dynamically taking higher frequency fixes ~15min when they have good solar power available most researchers actually weren't interested in that feature. They preferred slower predictable fixes like every 1hr.

Interested to hear people's thoughts/feedback.

Thanks in advance.

Thank you.  A couple of things I've done in getting a completely different GPS logging system running.

I do use a local clock to keep local time when the GPS is off.  Each time the GPS comes on and finally gets a fix, I reset the local clock.  The alarm function is then based off of the local clock rather than the GPS.  At least for the chipset I use, the local clock remains running even when in sleep or power down mode and draws very little power.  

Another way you might attack the problem if so you want 1 hour fixes, is to set the alarm for 50 minutes, leaving the GPS on just long enough to get a clock fix and then sleep for the calculated time it takes to get the on-the-hour fix.  I've found that with GPS modules with memory backup (usually a supercap or second small battery), the second fix will be pretty quick, so although there is more power consumption, it's not double what a single fix would be.

Anyway, it's an interesting problem.  Let us know how you elect to address it.

Chris H

FYI if you really want to go down a timekeeping rabbit hole, check out the Leap Second website. There are a lot of fascinating things you can do with precision timekeeping. 

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