Implausible Time Records

FYI, I’ve sent my file to Lxnav to see what they think.
My backup IGC file from the portable power Flarm was ok during the same time period and was accepted by OLC.

Dan,
Just FYI, I got the same error last night on an IGC flle from an Lx9070, so it may not be a CN issue.
lx9070 was updated to latest software version on 4/8/19.

This is what I see in my file:
B1813373310143N08621921WA0103001106006001113851177 3067-006602030130-041003
B1813383310151N08621903WA0103001106007004113561204 1053-004602030130-043003
B1813393310164N08621887WA0103001107006004111961228 5040-003602030130-042003
LLXVCLOCKJUMP
B1813373310179N08621875WA0103101107006004110891250 7026-003602030120-039003
B1813383310197N08621867WA0103201107006004110021274 0014-004102030120-038001
B1813393310216N08621863WA0103101107006004109261299 2002-004102030120-034001

Looks like both you and Dan show a UBLOX NEO as the GPS receiver, maybe
a problem with new firmware from the vendor?



On 5/19/19 7:03 AM, wrote:
Dan,
Just FYI, I got the same error last night on an IGC flle from an Lx9070, so it may not be a CN issue.
lx9070 was updated to latest software version on 4/8/19.

This is what I see in my file:
B1813373310143N08621921WA0103001106006001113851177 3067-006602030130-041003
B1813383310151N08621903WA0103001106007004113561204 1053-004602030130-043003
B1813393310164N08621887WA0103001107006004111961228 5040-003602030130-042003
LLXVCLOCKJUMP
B1813373310179N08621875WA0103101107006004110891250 7026-003602030120-039003
B1813383310197N08621867WA0103201107006004110021274 0014-004102030120-038001
B1813393310216N08621863WA0103101107006004109261299 2002-004102030120-034001

Kinsell, You may be on the right track.
Backup recorder (portable powerflarm) with separate gps system, recorded fine during the same period.

On 5/20/19 6:43 AM, wrote:
Kinsell, You may be on the right track.
Backup recorder (portable powerflarm) with separate gps system, recorded fine during the same period.


I notice your Oct 2 2018 flight on OLC had that peculiar highly
compressed altitude graph, but without the gps altitude dropouts. Maybe
that's just some unrelated OLC display issue.

Ublox receivers are used for many other applications besides flight
recorders, wonder why nobody else seems to be having problems.

I've been submitting from a PF Core the last few years, haven't seen any
of these issues.

Ref .
I notice your Oct 2 2018 flight on OLC had that peculiar highly
compressed altitude graph, but without the gps altitude dropouts. Maybe
that's just some unrelated OLC display issue.

Good observation, I didn’t notice that.
The one on 10/4 has the same compressed altitude issue, while the one on 10/3 looks ok, as does the flight on 5/1/19.
I have been posting to OLC from that particular 9070 for about 4 years and haven’t had a problem before now.

MS

I turned on my CN2 and CNvXC 20 minutes before engine start today. Then
it was another 15 minutes to warm up the engine before take off.Â* Even
though I had several GPS drop outs during the flight, it scored
perfectly.Â* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.Â* Looks like the work around is to
let the GPSs get time synchronized before take off.

On 5/5/2019 9:38 AM, Dan Marotta wrote:
For my last three flights I've been getting a message from OLC warning
of implausible time records in the igc file.Â* Does anyone know what
this means and what I might do to correct the problem? I've asked the
question on the ClearNav forum but haven't gotten a reply yet.

Here's a link to the file if that helps:
https://www.dropbox.com/s/erm01jilim...8Q-01.IGC?dl=0

--
Dan, 5J

On 5/25/19 6:58 PM, Dan Marotta wrote:
I turned on my CN2 and CNvXC 20 minutes before engine start today. Then
it was another 15 minutes to warm up the engine before take off.Â* Even
though I had several GPS drop outs during the flight, it scored
perfectly.Â* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.Â* Looks like the work around is to
let the GPSs get time synchronized before take off.

On 5/5/2019 9:38 AM, Dan Marotta wrote:
For my last three flights I've been getting a message from OLC warning
of implausible time records in the igc file.Â* Does anyone know what
this means and what I might do to correct the problem? I've asked the
question on the ClearNav forum but haven't gotten a reply yet. the

Here's a link to the file if that helps:
https://www.dropbox.com/s/erm01jilim...8Q-01.IGC?dl=0


Do the dropouts match up with published times for GPS jamming? Your
trace shows tons of gps altitude dropouts between about 15:00 and 16:00
local time, but clean otherwise. They do correspond to the NE leg of
your flight, but that may just be coincidence.

At 02:38 26 May 2019, kinsell wrote:
On 5/25/19 6:58 PM, Dan Marotta wrote:
I turned on my CN2 and CNvXC 20 minutes before engine start today. Then

it was another 15 minutes to warm up the engine before take off.Â* Even

though I had several GPS drop outs during the flight, it scored
perfectly.Â* BTW, all other devices in the cockpit, including my buddy's

iPad also lost GPS for those times.Â* Looks like the work around is to
let the GPSs get time synchronized before take off.

Basically, the Time in the IGC file originates in the GPS Engine. At
power-up it comes from the RTC, but once 'Satellite Time' has been received
and the correct number of Leap Seconds applied, the source switches to
that.

The difference can be in the order of 2 seconds, and this causes the
out-of-sequence times that OLC seems objects to.

There are two workarounds and you can use either or both.

1. Set the logging interval to 4 seconds or more, which will conceal the
2-second jump.

2. As you said, Switch on well in advance. 15 minutes is about right IMHO.
10 minutes is the time it takes to be assured that the time is correct, and
5 more to be sure that the FR has not back-logged the jump.

I tried to change either the logging interval or just the interval that
is downloaded after the flight but it was not intuitive after the
flight.Â* I guess a little ground study is in order.

As to the published interference testing times, I didn't check, but the
only dropouts I had were up around Las Vegas (the northeast part of the
flight).Â* Once moving south again, I did not see them again. As stated
before, I lost GPS on everything in the cockpit - all of my stuff and my
copilot's iPad, as well.Â* I'd bet on jamming.Â* I'll try to do better on
what and when next time.

On 5/26/2019 4:04 AM, Tim Newport-Peace wrote:
At 02:38 26 May 2019, kinsell wrote:
On 5/25/19 6:58 PM, Dan Marotta wrote:
I turned on my CN2 and CNvXC 20 minutes before engine start today. Then
it was another 15 minutes to warm up the engine before take off.ÂÂ* Even
though I had several GPS drop outs during the flight, it scored
perfectly.ÂÂ* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.ÂÂ* Looks like the work around is to
let the GPSs get time synchronized before take off.

Basically, the Time in the IGC file originates in the GPS Engine. At
power-up it comes from the RTC, but once 'Satellite Time' has been received
and the correct number of Leap Seconds applied, the source switches to
that.

The difference can be in the order of 2 seconds, and this causes the
out-of-sequence times that OLC seems objects to.

There are two workarounds and you can use either or both.

1. Set the logging interval to 4 seconds or more, which will conceal the
2-second jump.

2. As you said, Switch on well in advance. 15 minutes is about right IMHO.
10 minutes is the time it takes to be assured that the time is correct, and
5 more to be sure that the FR has not back-logged the jump.




--
Dan, 5J