At 21:27 20 May 2019, kinsell wrote:
On 5/20/19 2:42 PM, wrote:
I’ve not heard back from Lxnav yet, but I had a private email from a
very smart person that pointed out that both the October 2 and October 4
flights had the clock jump after takeoff but before soaring began. The
flight this week had the clock jump a minute or so after soaring began,
and
thus is likely why OLC flagged this one and not the other two. It
appears
that the clock jump is 7 to 8 minutes after the unit is turned on. Since
I
generally do not turn the system on until just before takeoff, it is
believed that the system is using an internal clock until it syncs with
the
gps satellites and then resets the clock which may be different by a
couple
of seconds. My plan is to turn the 9070 on a few minutes before launch
to
allow it to sync clocks to see if that helps. It is not clear to me if
Dan’s issue is similar to mine or different.

MS


They do have clocks to help achieve lock on the satellites, but I've
seen the reported time jump immediately after lock was achieved. Don't
know why the 9070 would wait minutes after achieving lock before
correcting the time. Maybe an issue of 2D vs 3D lock. If you're
turning on the logger immediately before takeoff, you're risking losing
the early part of the flight entirely, not just having time problems.

Dan was having lots of gps altitude dropouts during flights, that might
just be jamming. He did have a time jump just at liftoff, so that fits
in with switching the clocks.

I've looked at Dan's trace, and the dropouts are in the latter part of the
flight,
nowhere near the time when the clock problem occurs, so probably not
jamming. Micheal's flight shows no GPs dropouts at all, but still
experienced
the problem.