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#61
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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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