I have two identical Pixhawk clones on the bench, one running Copter V3.3.3 and one running Plane V3.6.0. I was testing a new Ublox M8/compass GPS module and noticed a significant difference in the number of satellites reported on Mission Planner.
With the GPS at a fixed position and connected to the Pixhawk running Copter V3.3.3, Mission Planner reports 10 satellites and 3D DGPS fixes. When the GPS is transferred to the second Pixhawk running Plane V3.6.0, Mission Planner reports 17 satellites and 3D DGPS fixes.
I am at a loss as to why the number of satellites would vary with different firmware. I have a consistent set-up of the GPS parameters (acknowledging that there are differences between Copter and Plane). Has anyone else experienced this or have suggestions as to how to get the Copter performance up to that seen with Plane?
To remove the potential of an issue with the Pixhawk, I flashed the “Plane” Pixhawk with Copter V3.3.3. Again, Mission Planner reports only 10 satellites. Reloading Plane V3.6.0 and the number of satellites jumps back to 17.
I think it is your configuration.
You have one thing blocking or perturbing GPS signal …
Could be power module, battery, or telemetry => http://diydrones.com/forum/topics/433-mhz-dipole-vs-gps-total-decimation
Test was on the bench with only the Pixhawk and the GPS unit so there was nothing else to impact the test. The jump in satellites reported changed with the software load and was repeatable. Not sure if Copter and Plane deal with the GPS configuration and control differently or if there is any difference in how the GPS status data is sent over MAVLINK.
Ok I didn’t notice that your are running on the bench.
Note that have more GPS satellite doesn’t means that GPS is better. HDOP and PDOP are more important. May be on copter mask of GPS is better, did you check this :
GPS_MIN_ELEV: Minimum elevation
Note: This parameter is for advanced users
This sets the minimum elevation of satellites above the horizon for
them to be used for navigation. Setting this to -100 leaves the minimum
elevation set to the GPS modules default.