What exactly do you need this for? :-) Do you need an accurate absolute time reference or would relative suffice? The empeg tied to a GPS receiver will be accurate within a few seconds of GPS time (or UTC, depending on the receiver.)

There are certainly ways of maintaining sub-second resolution but I do not know how to do it from user land on this platform.

I hadn't planned on implementing the $PTNL,GGK sentence. My GPS unit doesn't generate it, not sure it's even a standard sentence. By the time the sentence has been sent, read and interpreted that sub second resolution is of little use. RMC has the time to 1 second and I'm already handling that.

I will set the empeg clock once in a while, perhaps every 10 minutes while it has a good lock. Setting it too often introduces jitter which I imagine would be bad for your use.

Cheers,

Rex.