Satellites

[bkushner]

Was wondering why I get 33 stas on my Mini 3 but 22 on the Mavic 3 in the exact same location?

 

[Meta4]

Was wondering why I get 33 stas on my Mini 3 but 22 on the Mavic 3 in the exact same location?

At the same time?

 

[bkushner]

At the same time?

Actually yes.

 

[SkyeHigh]

Was wondering why I get 33 stas on my Mini 3 but 22 on the Mavic 3 in the exact same location?

We’re they both started up at the same time, ie, not just taking readings at the same time?

I would have expected a higher count with the Mavic 3 with its access to the Beidou network of satellites but it could be based on the time difference between when the almanac tables were loaded on each device.

Although the satellite count is shown it doesn’t always mean it is using all of them to compute location, rather the number currently in view of the receivers. Most ‘GPS’ receiver chips have 66-receivers spread across the respective transmission channels and all of those channels are available to the drone’s Flight Controller. Usually a maximum of 33-satellites can be tracked simultaneously with the remainder in a search mode. What the Flight Controller does with them is down to whatever algorithms DJI have implemented and that may vary between different models.

It would be interesting to know if you see this on a regular occurrence.

 

[teccer]

We’re they both started up at the same time, ie, not just taking readings at the same time?

I would have expected a higher count with the Mavic 3 with its access to the Beidou network of satellites but it could be based on the time difference between when the almanac tables were loaded on each device.

Although the satellite count is shown it doesn’t always mean it is using all of them to compute location, rather the number currently in view of the receivers. Most ‘GPS’ receiver chips have 66-receivers spread across the respective transmission channels and all of those channels are available to the drone’s Flight Controller. What the Flight Controller does with them is down to whatever algorithms DJI have implemented and that may vary between different models.

It would be interesting to know if you see this on a regular occurrence.

on my P3P the most sats I got from my house was 19 but always with my mini2 it is in the 26-30 range !!

 

[SmilingOgre]

Antenna theory is very complex. Signal propagation can be effected by many variables. Obviously as long as you get a good GPS lock I wouldn't worry.

 

[Meta4]

I would have expected a higher count with the Mavic 3 with its access to the Beidou network of satellites

Both use GPS + Galileo + Beidou

on my P3P the most sats I got from my house was 19 but always with my mini2 it is in the 26-30 range !!

The Mini 2 accesses 50% more sats since it uses GPS + Glonass + Galileo
The P3P only has GPS + Glonass

 

[Meta4]

Was wondering why I get 33 sats on my Mini 3 but 22 on the Mavic 3 in the exact same location?

It would be interesting to know if the two consistently show a similar difference or if it is just an occasional thing.

 

[Dave Maine]

The interesting thing would be if they came up with different locations.

The satellite count isn’t terribly important so long as you have enough. The FMS takes that data plus the IMS data to calculate speed, altitude, and position. This integration works fine with 8-12 satellites. Theoretically a fix can be achieved with 3. DJI is very conservative asking for many more before validating the integration results.

 

[Meta4]

The satellite count isn’t terribly important so long as you have enough. .... This integration works fine with 8-12 satellites.

"Enough" is only part of the issue.
For proper location data, you also need a suitable spread of satellites to provide good triangulation.
And with later models using three different sat constellations, you need a larger number of sats than with earlier models that only used two.
People come unstuck all the time because they think that 8 or 10 or 12 is the magic number.
A modern DJI drone under an unobstructed sky should be showing high 20s- low 30 sats.
If it's only showing 10 or 12, it's probably because most of the skyview is blocked andGPS is probably still not good enough to record a home point.

For full GPS reception you need to wait until the satellite icon, top right of screen, turns white.