GPS signal question

[Chuck Krause]

What is the determining factor of getting a reliable gps signal? Number of satellites acquired? Reason I ask is the location I'm anticipating is a deep canyon with steep side walls where my past experience has shown me I get half the normal sats acquired I would get out in the open. My handheld Garmin can get a solid signal with just 3-4 but I've seen the Spark with 8 and it will call it week and not use it. I'm new to drones and the Spark but have used gps in many other applications. Sorry if this sounds stupid but I'm trying to learn.

 

[Dronason]

What is the determining factor of getting a reliable gps signal? Number of satellites acquired? Reason I ask is the location I'm anticipating is a deep canyon with steep side walls where my past experience has shown me I get half the normal sats acquired I would get out in the open. My handheld Garmin can get a solid signal with just 3-4 but I've seen the Spark with 8 and it will call it week and not use it. I'm new to drones and the Spark but have used gps in many other applications. Sorry if this sounds stupid but I'm trying to learn.

Accuracy and stability of the position defined by the GPS. More satellites, less error (in general) and less jump in position due to change of number of satellites (either the drone moves or the satellites move).

 

[Dick]

Apples and oranges..........your garmin is only interested in 2D, that is......where are you (on the ground) on the earth's surface, unfortunately drones "fly", thus altitude presents a 3D problem, not 2D.........instead of 3 sats they need 6 minimum........

 

[Dronason]

In Phantom 3, the GPS altitude is not used. It is a barometer that control the altitude by measuring air pressure. GPS is critical as it define where the flight controller think it is and if that position jumps by 10 meters, then the drone will jump by 10 meters. On low cost Drones that use GPS, this is where they suck. In the Spark it should be the same IMO. So it always try to define asap if GPS quality goes down to switch to ATTI mode. Also having Glonnass satellites in addition to GPS help a lot to have continuously many satellites and maintain a high quality of the position.