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answer about galileo #3

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Maxym77 opened this issue Aug 26, 2018 · 23 comments
Closed

answer about galileo #3

Maxym77 opened this issue Aug 26, 2018 · 23 comments
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question Further information is requested

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@Maxym77
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Maxym77 commented Aug 26, 2018

Hi and thanks.
After installed firmware now i see 22 sat instead of 14 normally take.
I can assume gallileo option is enabled?
I don't have used NLD software... only DJI Go 4

Max

@Matioupi
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Matioupi commented Aug 26, 2018 via email

@Maxym77
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Maxym77 commented Aug 26, 2018

I haven't performed any step of the 15. Additionnal "post-install" steps to get Galileo working.

you are saying that there is a possibility that galileo will work ?

by the way now i verify with last flight data from the bird blackbox.

Max

@Matioupi
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Maybe it can work. From my previous testings, I needed to feed the receiver once with downloaded ephemerids to get it working (which is handled by the app sdie mod)

Now that there are more active Gal sats, it may happen that this is not necessary anymore...

Please test as explained above and report...

@Maxym77
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Maxym77 commented Aug 26, 2018

image

@Maxym77
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Maxym77 commented Aug 26, 2018

what do you think about it? am i using the galileo network?

@Matioupi
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you are seing 12 sats, amongst those 4 GPS, 5 Glonass, so the 3 missings are Galileo !

Thanks for testing, this seems to mean that with current constellation status, it's not even needed to do a first "manual" ephemerid load.

If you want to make a flight at a time were there will be a lot of sats, you can use the app given at the end of readme to check the best time slots at a given location.

@Maxym77
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Maxym77 commented Aug 27, 2018

with this patch I notice a different behavior in mavic. when I am on the ground, see the GPS switching from 0 sat to 10 sat ... max 14 .. when i take off and go at 20 meters i see 16-18-20 sat ..
when I land sometimes it goes back to zero sat

@Matioupi
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The GNSS receiver configuration applied with the patch is as follow

elevation mask above horizon : 5° (same as DJI default)
constellations : GPS+GLO+GAL (DJI default : GPS+GLO)
receiver mode : airborne < 2g (DJI default : portable generic)
max PDOP : 10 (DJI default : 25)
fix type : 3D only (DJI default : allows 2D fixes)
max horizontal standard deviation : 30m (DJI default : 100 m)

Those settings (and espacially the "airborne" one may apply more restrictive filters to sat meausrements while on the ground.
I believe it's better to be slighlty more restrictive on which sats the receiver is allowed to use (better fix quality) than risking to take-off with a pos with lots of multi-path measurements that may trigger an inconsistency between GPS and compass while in the air.

Having slighlty different behaviour especially in the way you report them is normal.

@Maxym77
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Maxym77 commented Aug 27, 2018

i have returned to official 01.04.0300 for test.
Restored to default settings.
I take 22 satellite galileo included! what is possible this?

image

@Matioupi
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I never noticed that before, but this is probably because the official FC is not issuing the constellation configuration message to the GNSS receiver.
So all settings that are used "as default" by DJI (not specifically issuig a configuration message) are left in the state that the modded FC left them.

This can be changed by making a modded FC that returns the GNSS configuration to default, and then flashing back to .07 (but obviously I don't see the point of doing this).

All material to do that is included in the scripts Just change the args from the "ubxcfggen" calls to achieve the settings you want (at your on risks)

@Matioupi Matioupi added the question Further information is requested label Aug 27, 2018
@Maxym77
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Maxym77 commented Aug 28, 2018

i take 2 compass error today... too weak gps signal in my zone... please answer issue #4 for GPS restock to default thanks!

@RazorCopter
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Based on the analysis of the ubox m8n associated with the arducopter (APM) project, we had defined this configuration as safe:

elevation mask above horizon : 10°
constellations : GPS+GLO+GAL
receiver mode : airborne < 4g
max PDOP : 10
fix type : 3D only (DJI default : allows 2D fixes)
max horizontal standard deviation : 100m or 150m

https://drive.google.com/file/d/1i_uqNQXwztqO7tRMvxxAT4JrsYxU2DM1/view?usp=sharing
read page 18

@renton82
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What could be wrong with previous gps parameter?

@Matioupi
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I don't believe there is anything wrong with the parameters as they are at time in the scripts.
One user reported he faced 2 compass error since he modded. Not a single beta tester did report such behaviour.
Same user seems to have issues reverting to standard GNSS settings, but I can't test this by myself right now. I'm not sure he applied the patches correctly etc.
To be honest, reading the code again, I don't see any reason why replacing the parameters as I proposed in #4 would result in seeing no satellites at all.

@Maxym77
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Maxym77 commented Aug 28, 2018

i have solved my problems (poor gps signal on land) increasing only max horizontal standard deviation from 30 to 100. now i take 14 satellite minimum on land

@Matioupi
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I'll be a bit rude, please excuse that, but I believe you don't understand anything to the settings you are changing...

The elevation above horizon has never been 30. It's 5, and rising it will only reduce the number of satellites the receiver is allwoed to track (but it will track slighlty better sats as lower ones provide "bad" measurements")

The parameter that is 30 is "pacc" (position accuracy) and it's the minimum accuracy that the GPS must estimate to spit out a position. Setting it to 100m will indeed result in a receiver spitting a position sooner/in more harsh conditions than 30m but this position is "risky" as it may be 100m inaccurate.

Obvisouly, the number of tracked satellties depends mostly on the time of day you are making the experiments.

@renton82
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I have never had any issue at all with post #4 parameters, only an improvement... in the same place where before i locked 12-13 sat, now i lock 15-16 min... my mavic never drop to 0 sat... I don't know what to think...

@Maxym77
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Maxym77 commented Aug 28, 2018

Matioupi no problem.
I have rollback to your original parameters.
At the moment mavic works fine.
I have take 27 satellite today on air.
My problem is only on ground.
I think i have interferences on my ground (metal net 10 cm under the cement ground, etc).
No more compass error today after 2 hours of fly.
Anyway, please, make a script for reset gps to default setting or give me an solution for dump current gps settings from other mavic.
thanks

@Matioupi
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I'll push a script to revert to standard GNSS settings as soon as possible. However, I would really advise you to stick with the modified config. I really believe it is safer.

You cannot dump GNSS settigns from another Mavic without openning it an putting some probes in it.

@o-gs o-gs deleted a comment from chinger1313 Aug 29, 2018
@Matioupi Matioupi closed this as completed Sep 2, 2018
@diikoo
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diikoo commented Sep 24, 2018

I can not remove NFZ in paramaetrs for p4p v2.0 how it remove

@TLozanov
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TLozanov commented Sep 25, 2018 via email

@talhats
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talhats commented Nov 4, 2018

i also can not remove NFZ cos it need a little bit description

@talhats
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talhats commented Nov 5, 2018

please can you help me for this error ([dji_image_verify_file:17] ERROR fail to open file wm335_0306_v03.03.04.13_20180525.pro.fw.sig
failed to verify image wm335_0306_v03.03.04.13_20180525.pro.fw.sig, error=-1)

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