Implausible Time Records

On 5/7/19 10:23 AM, Tom Kelley #711 wrote:
On Tuesday, May 7, 2019 at 9:21:33 AM UTC-6, Dan Marotta wrote:
An interesting thought, but I see the same whether I'm using the
ClearNav or the ClearNav vario.Â* I doubt both could be experiencing the
same fault at the same time.Â* It's really odd about the apparent time
compression on the OLC display.Â* My flights score and appear just fine
on skylines.aero.

On 5/7/2019 8:21 AM, kinsell wrote:
Looking at your flight logs on OLC, you have the last two that didn't
validate, but others earlier this year that did.

However, most of the altitude graphs are plotted with many hours of
dead time, with the flight being compressed into the very right hand
part of the graph. A very bizarre presentation.

Perhaps your ClearNav has a hardware fault that is gradually getting
worse?



On 5/6/19 4:20 PM, Dan Marotta wrote:
These dropouts never occur during engine run which normally only runs
10 minutes or less from engine start to shutdown after takeoff.

Heating up the dielectric is something I didn't consider.Â* Maybe I
should replace the antennae...

On 5/6/2019 11:39 AM, kinsell wrote:
On 5/6/19 10:32 AM, Dan Marotta wrote:
I've also had drop outs with my Trig TN-70 and its antenna, though
not as often as with my soaring GPSs.

Do they correlate with the engine running?Â* If so, might be ignition
noise.



Yes, the wires are tiny, but it was pretty simple to desolder them
from the puck, clip the cable to length, strip, tin, and solder.Â* I
did that for 3 antennae and they generally work fine, but lately
have acting up.

It's easy to overheat the dielectric in the coax, causing loss of
signal strength.



I'm looking at THESE
https://www.amazon.com/CIROCOMM-Antenna-Ceramic-25x25x2mm-Geekstory/dp/B078Y2WNY6?ref_=Oct_TopRatedC_3248676011_1&pf_rd_p =57ac2d87-b669-53fa-a2b6-2c15e8d66f28&pf_rd_s=merchandised-search-6&pf_rd_t=101&pf_rd_i=3248676011&pf_rd_m=ATVPDKIKX 0DER&pf_rd_r=GNQVSWJ3FAVNDTDDJJDS&pf_rd_r=GNQVSWJ3 FAVNDTDDJJDS&pf_rd_p=57ac2d87-b669-53fa-a2b6-2c15e8d66f28
as replacements.Â* Any comments?Â* I wonder if that IPEX connector is
a push fit on the built in SMA connectors on the devices. I'm also
considering replacing the modified antennae with factory new units
and using the longer cables to mount them on opposite canopy rails
in the Stemme.Â* Those should be about a meter apart.

On 5/6/2019 9:44 AM, kinsell wrote:
Jamming is directed skyward, they're not taking out car gps's in a
400 nm radius.Â* If you're getting bad time stamps just at liftoff,
it's not likely caused by jamming.

I'm suspicious of your cut-down gps cables, those are tiny wires
to be working on.



On 5/6/19 9:08 AM, Dan Marotta wrote:
Yes, the GPS jamming usually centers around Alamogordo and ranges
out to about 400 nm.Â* Moriarty is well within that area.Â* I've
asked other local pilots and they don't report so many drop outs.

Maybe there are just too many GPS antennae in my ship. I'll take
a look at a divider for everything except the ADS-B WAAS GPS.
Its antenna is mounted aft of the engine in the Stemme. The rest
are on or under the glare shield.

On 5/5/2019 7:42 PM, JS wrote:
On Sunday, May 5, 2019 at 3:43:24 PM UTC-7, Dan Marotta wrote:
Thanks Tim

I'll increase my time interval to 2 seconds and see if that helps.

Strange that the igc file does not show GPS drop outs since my
ClearNav
screen went white with the caption (something like) No GPS. Zero
satellites.Â* And the ClearNav vario said, "Warning no GPS". The
PowerFlarm portable screen also went blank with a "Zero
satellites" message.

On 5/5/2019 1:05 PM, Tim Newport-Peace wrote:
Dan,

Open your file with a text editor and search for "B190338"
This will put you in the right area.
In each record, after the letter B, the next six bytes are the
time.

After B190339 the time jumps back toÂ* B190337, which is odd,
and leads to
there being two records with a time of 190338, and also 190339.

Odd, but I have seen this before. Maybe you can avoid it in
future by
setting a longer fix interval, even 2 seconds might help, but
no promises.

I am not seeing any GPS outage around that time. This would be
shown by the
Letter "A" in the 25th byte changing to a "V".

Although it does not help a lot, the sequence error seems to
happen as you
left the ground, so I guess you were not reversing turns?

I'm not saying this is what OLC are complaining about, just
that it is odd
and it might be.

Tim.
--
Dan, 5J
That smells of GPS jamming.
Check this page.
https://www.navcen.uscg.gov/pdf/gps/...terference.pdf
I did not have a problem with the vario file today. My antenna
has a shortened cable to a MECA divider, then a short SMA-SMA
link cable.
Jim



--
Dan, 5J




--
Dan, 5J

Dan, my ClearNav XC logger, when downloaded to the OLC, appears to display the same as yours(time compression to the right). I used my Flarm IGC logger and it appears normal for the OLC. Yet on Skyline aero, Cross-country aero and See you, the ClearNav logger displays and views as normal.

The last several flights I have had experience GPS dropouts, which on Sunday seemed odd, and lasted only several minutes at a time(I fly out of KALM and the loss of signal was in numerous areas on Sunday). All the updates have been done, now several times over, yet the ClearNav logger and OLC just don't get along, yet the flight is scored and shows valid. Don't get an OLC speed when using the ClearNav.

When you figure this out, let us know!

Best. Tom #711


Your May 3 flight is interesting. Hours worth of altitude data is
missing on the OLC graph, but the rest of the trace is shown. This is
different than the altitude data being compressed to the right.

Looking at the GPS altitude on SeeYou, there's one dropout of data
towards the end of the flight, apparently at the point where OLC started
showing altitude data on their graph.

So maybe one short loss of data is screwing up the OLC scoring and graphing.