14 sats but not enough to get home point?

[Buel]

Hi all.

I just tried to fly and could see that it said I had 14 satellites but the icon was red and wouldn't let me get my home point and resttricted height etc. If I flew up to max height and stayed a minute then it would gain enough sats to fly, but then I would come down to 4 m and it would lose them again.

This is at my home where I have always enjoyed lots of sats and no issue previously.

Any ideas, please?

 

[mavic3usa]

My understanding is there's more to GPS and location than just "getting" satellites. I would do some basic research on consumer-grade GPS, how they get a fix, the quality of the signal, etc and go from there. Behinds the scenes, there's really a lot going on there....

 

[Phantomrain.org]

Nothing Wrong with flying up to get signal, you will be fine when you come back as you most likely will not loose signal as its harder to loose than gain.

Phantomrain.org
Gear to fly your drone in the Rain, Land on the Water.

 

[slup]

...I had 14 satellites but the icon was red and wouldn't let me get my home point

Good positional data aren't just dependent on the number of locked satellites... in the logs you also find something that DJI calls GPSLevel (or Navhealth), it's a kind of confidence computation that tells the flight controller if it can trust the positional data or not.

The GPSLevel have values from 0 up to the best 5. The HP isn't recorded until it comes up to a 4 for instance. If the GPSLevel is low you may see messages about GPS and/or Compass signal weak... & if reaching 0 you will have a switch to ATTI mode.

Exactly what's included in the GPSLevel isn't fully clear, but it involves GPS DOP & the compass.

Below an example from another flight... 27 satellites locked, 0 in GPSLevel .... & therefore that drone was in ATTI mode.

(Click on the chart to make it larger)

 

[Buel]

This is both fascinating and annoying
Thank you for this. The thing that confuses me is that is super normally? Perhaps agreeing to download the new software update and some calibration may help?

 

[Meta4]

This is both fascinating and annoying
Thank you for this. The thing that confuses me is that is super normally?

That's uncommon, but not unusual.
The time taken and number of sats before you have full GPS quality is quite variable and affected by a number of different factors.
I have seen it take >20 sats before being able to record a home point on occasion.

The sats are orbiting the earth while the earth rotates inside the "cage" their paths trace in space.
Which sats are visible in your sky and how many is changing all the time.
The number of sats acquired is only one factor.
Their spread across the sky is also important.
If they are all bunched in one part of the sky or in a line, you won't have suitable geometry to provide the required spread of sats.
Perhaps you just encountered an unusual random bunching of sats?
Does your launch point have a clear, unobstructed all-round skyview or is part of the drone's skyview blocked by buildings, terrain or tree cover?

Perhaps agreeing to download the new software update and some calibration may help?

No .. that won't make any difference to GPS sat acquisition times.
How long since you last flew is another factor that will affect sat acquisition times.

Time to first fix - Wikipedia

en.wikipedia.org

 

[Buel]

part of the drone's skyview blocked by buildings, terrain or tree cover?
Great question - yes it is

How long since you last flew is another factor that will affect sat acquisition times.
Interestingly, only a week but two months before that!

 

[Meta4]

part of the drone's skyview blocked by buildings, terrain or tree cover?
Great question - yes it is

This is a major factor.
The number of sats your drone can see is roughly proportional to the percentage of the sky it sees.
And more than the number of sats, it also means that the sats your drone does see, are more likely to be bunched and not giving the wide spread that's needed for good GPS location data.
Launch from somewhere that the drone can see the full skyview and things will be different for you.

 

[Buel]

I tell you what, everyone, it is still doing this even when not near buildings - it takes about 4 minutes of being 50ft up before it eventually fins the sats and gets it's home point?

 

[Phantomrain.org]

I have a mavic 3 Pro that needs to get up about 10 Ft to catch the Home point , not sure why this is as my other drones catch home point on the ground off the same spot.

Phantomrain.org
Gear to fly your drone in the Rain, Land on the Water

 

[Buel]

Hi all.....I am still having real problems getting enough satellites where I never used to with my Mini 2....any more ideas, please?

 

[Meta4]

Hi all.....I am still having real problems getting enough satellites where I never used to with my Mini 2....any more ideas, please?

Apart from using the drone out in the open where it has a clear, unobstructed skyview, there's nothing you can do to improve GPS reception

 

[Buel]

Hmmmm......another issue - I 100% have my settings set so that the drone flies up to 110ft on RTH but it just does not do it?

 

[MS Coast]

Hmmmm......another issue - I 100% have my settings set so that the drone flies up to 110ft on RTH but it just does not do it?

You might want to review the RTH information in the manual. RTH behaves differently depending on the distance from the home point. If the drone is close to the home point, it will not climb to the set altitude. Check whether you have RTH set to Optimal or Pre-Set. The Optimal setting doesn't always cause a climb to the set altitude.

Here's a rather lengthy video tutorial on RTH for the Mini 4 Pro.

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[High_Order1]

Do you have any metallic stickers or paint that might be degrading the signal?

The only thing I know from outside of mavic world is an issue where the almanac doesn't update like it should.

 

[Buel]

Do you have any metallic stickers or paint that might be degrading the signal?

The only thing I know from outside of mavic world is an issue where the almanac doesn't update like it should.

Boom! Brilliant - Yes I do have metallic stickers on them in the event of ever losing it!!! I wonder if this could be it!!

 

[MS Coast]

Boom! Brilliant - Yes I do have metallic stickers on them in the event of ever losing it!!! I wonder if this could be it!!

Are they actually metal or just metallic-looking mylar? Where are they?

 

[Buel]

Here you go.....I am excited at finding out if removing them works....

 

[rwilliam99]

Here you go.....I am excited at finding out if removing them works....
View attachment 181844
View attachment 181844View attachment 181845

I will bet that the one on the top is the culprit - I believe the GPS sensor is underneath that tape.

 

[mavic3usa]

Hi, if you don't mind, could you please tell us why those pieces of tape are applied to your drone? Are you trying to deter birds or improve the VLOS or hide the written details underneath or is it for decoration?