L5 Data cuts out - Pixel 4

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and...@navmatic.io

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Dec 1, 2020, 12:54:50 PM12/1/20
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Hello!
I was collecting some static data with a Pixel 4 device and noticed that the L5 data is intermittent. I was wondering if this is a common issue and if there are ways to collect continuous L5 data.

Thanks!
Andrew Wu  


Graphs from the GNSS Analysis tool

All Signals SNR
all_signals_snr.png

L1 SNR
L1_snr.png
L5 SNR
L5_snr.png
I notice the clock continuity seems to be correlated with L5 signal availability. Maybe that's a clue?

andras.l...@gmail.com

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Dec 1, 2020, 1:53:04 PM12/1/20
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Hi Andrew,

I suppose something is wrong in your Pixel4, maybe it needs a restart or it is a ROM bug (then You cant do nothing)

Here it is my L5 SNR sheet from a short tracklog with my Xiaomi MI8 :



BR,
Andras

andras.l...@gmail.com

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Dec 1, 2020, 1:55:03 PM12/1/20
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i can't attach pic somewhy...

here is a weblink: https://ibb.co/W0CBp4L

BR,
Andras

Sean Barbeau

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Dec 1, 2020, 2:17:47 PM12/1/20
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Andrew,
Do you have the Android system Developer Option for "Force full GNSS measurements" enabled?

Sean


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and...@navmatic.io

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Dec 1, 2020, 7:16:12 PM12/1/20
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Aha, I don't!

I'll run another test with that setting on and report back. Thanks

Sean Barbeau

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Dec 17, 2020, 2:42:00 PM12/17/20
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Andrew,
Did you ever test this again?

I've actually been meaning to do a short blog post about the "Force full GNSS measurements" feature as it's not well documented, and having a before and after image like the one you shared above (assuming this is the problem) would be awesome :).

Thanks,
Sean

and...@navmatic.io

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Dec 18, 2020, 9:12:39 PM12/18/20
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I haven't yet, but I'll try to get a clean log this soon.

and...@navmatic.io

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Dec 24, 2020, 5:31:12 PM12/24/20
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I wasn't able to run this through the analysis before the holiday break, but I captured this log: https://drive.google.com/file/d/11_92Fw5ItLSxYIraVZY0GinuwhAW1qpH/view?usp=sharing

I'll run it through (or cap a new one if it's not enough) in the new year

andras.l...@gmail.com

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Dec 24, 2020, 5:41:03 PM12/24/20
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Hi Andrew,

Something is not with this log, i got the following error message during the loading:
Analyzing log file ...
Number of satellites with Bad Measurements = 29 : 21 with FullBiasNanos not available
No epoch with valid pseudorange in ProcessGnssMeas
No valid measurements to process or plot


BR,
Andras 

and...@navmatic.io

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Jan 11, 2021, 9:42:02 PMJan 11
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Ok, got a chance to collect a cleaner log here:


I was able to run it through the Analysis Tool to generate the following SNR graphs, too

All Sats

allsignalssnr.png

L1 Sats

L1SNR.png

L5 Sats

L5SNR.png

Sean Barbeau

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Jan 12, 2021, 1:16:11 PMJan 12
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Andrew,
So that looks much better for L5, right? It seems the "Force full GNSS measurements" setting worked?

I see some cutouts, but those are likely naturally lost signals.

Sean

and...@navmatic.io

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Jan 12, 2021, 1:48:18 PMJan 12
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Yup, "Force full GNSS measurements" seemed to be the trick.
The clock signal stays continuous, too.

Thanks again for the tip

Sean Barbeau

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Jan 25, 2021, 12:53:56 PMJan 25
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Andrew,
I wrote a blog post on this here:

Thanks again for the images! Hopefully people find this useful.

Sean
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