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Implausible Time Records



 
 
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  #61  
Old May 26th 19, 01:58 AM posted to rec.aviation.soaring
Dan Marotta
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Posts: 4,601
Default Implausible Time Records

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.ツ* Even
though I had several GPS drop outs during the flight, it scored
perfectly.ツ* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.ツ* 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.ツ* 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
  #62  
Old May 26th 19, 03:38 AM posted to rec.aviation.soaring
kinsell
external usenet poster
 
Posts: 546
Default Implausible Time Records

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.ツ* Even
though I had several GPS drop outs during the flight, it scored
perfectly.ツ* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.ツ* 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.ツ* 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.
  #63  
Old May 26th 19, 11:04 AM posted to rec.aviation.soaring
Tim Newport-Peace[_6_]
external usenet poster
 
Posts: 65
Default Implausible Time Records

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.ツ* Even


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


iPad also lost GPS for those times.ツ* 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.



  #64  
Old May 26th 19, 04:56 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default Implausible Time Records

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.ツ* 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).ツ* 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.ツ* I'd bet on jamming.ツ* 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.テつ* Even
though I had several GPS drop outs during the flight, it scored
perfectly.テつ* BTW, all other devices in the cockpit, including my buddy's
iPad also lost GPS for those times.テつ* 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
  #65  
Old May 26th 19, 05:10 PM posted to rec.aviation.soaring
Papa3[_2_]
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Posts: 753
Default Implausible Time Records

Adding anecdotal evidence to the startup idea... I had my first-ever "implausible time record" failure on my ClearNav two weeks ago. It was an unusual flight, as I realized after takeoff that I didn't have the right databases loaded (turnpoints and airspace) since I was flying "off the map" from our typical task area (it was a really good day). About 45 minutes into the flight I went to load the full US Airspace file, and the ClearNav locked up. I power cycled it and it cleared everything, but a few minutes after the approximate point of the power cycle I got the implausible time record. I did get another one later in the flight as well, but all flights before and since have been fine.

P3
  #66  
Old May 26th 19, 10:58 PM posted to rec.aviation.soaring
Tim Newport-Peace[_6_]
external usenet poster
 
Posts: 65
Default Implausible Time Records

At 15:56 26 May 2019, Dan Marotta wrote:

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).ツ* 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.ツ* I'd bet on jamming.ツ* I'll try to do better on


what and when next time.

Interestingly, in your flight 2019-05-04-CNI-V8Q-01, not only were there
lots of loss of 3D logging (dropouts), but around 22:23:09 (UTC) the GPS
altitude rose to an amazing 163,215 feet (Eat you heart out Perlan).



  #67  
Old May 27th 19, 01:59 AM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default Implausible Time Records

Yaas...ツ* My cannula was working over time!

On 5/26/2019 3:58 PM, Tim Newport-Peace wrote:
At 15:56 26 May 2019, Dan Marotta wrote:

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).テつ* 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.テつ* I'd bet on jamming.テつ* I'll try to do better on
what and when next time.

Interestingly, in your flight 2019-05-04-CNI-V8Q-01, not only were there
lots of loss of 3D logging (dropouts), but around 22:23:09 (UTC) the GPS
altitude rose to an amazing 163,215 feet (Eat you heart out Perlan).




--
Dan, 5J
  #68  
Old May 27th 19, 03:07 AM posted to rec.aviation.soaring
kinsell
external usenet poster
 
Posts: 546
Default Implausible Time Records

Sure would be nice if the gps engines could filter out the worst of
this. 16K to 0 or 160K in a second seems rather umm implausible.

If it is jamming, as it sounds like, expect it to get nothing but worse.


On 5/26/19 9:56 AM, Dan Marotta wrote:
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.ツ* 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).ツ* 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.ツ* I'd bet on jamming.ツ* 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.テつ* Even
though I had several GPS drop outs during the flight, it scored
perfectly.テつ* BTW, all other devices in the cockpit, including my
buddy's
iPad also lost GPS for those times.テつ* 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.





  #69  
Old May 27th 19, 04:44 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default Implausible Time Records

The FAA wants to be notified if loss of GPS guidance affects flight
safety.ツ* I have heard reports from airliners over New Mexico that have
lost GPS.ツ* The FAA can issue an order to the military to stop the
jamming if flight safety is an issue.ツ* I've also lost my IFR certified
WAAS GPS/ADS-B in the C-180.ツ* I reported it to ABQ Center and they asked
if I needed assistance.ツ* Flying between mountain ranges with 100+ mile
visibility, I could pretty much see my destination.ツ* It's the same in
gliding with the only problem being corrupt igc files.

On 5/26/2019 8:07 PM, kinsell wrote:
Sure would be nice if the gps engines could filter out the worst of
this.ツ* 16K to 0 or 160K in a second seems ratherツ* umm implausible.

If it is jamming, as it sounds like, expect it to get nothing but worse.


On 5/26/19 9:56 AM, Dan Marotta wrote:
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.ツ* 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).ツ* 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.ツ* I'd bet on jamming.ツ* 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.テつ*
Even
though I had several GPS drop outs during the flight, it scored
perfectly.テつ* BTW, all other devices in the cockpit, including my
buddy's
iPad also lost GPS for those times.テつ* 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
  #70  
Old May 28th 19, 04:48 PM posted to rec.aviation.soaring
Tango Eight
external usenet poster
 
Posts: 962
Default Implausible Time Records

How to change the igc flight log time interval on CN2:
https://youtu.be/AkJwwCbGMZQ

CN2 stores logs internally at 1 second. You can d/l to USB at 1, 2, 4 or 10 second intervals.

Please pay close attention to the voice over. There is one especially non-obvious press of the down arrow key.

We think that d/l at 4 second interval solves (really: masks) the discontinuity that occurs when the UTC - GPS time offset update is received from the GPS system.

best regards,
Evan Ludeman for CNi
 




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