WikiSysop: Created page with "Several sources of error make raw GPS measurements inaccurate. To make up for this, consumer GPS receivers use a "model" to help determine what part of the measurement is erro..."

2016-02-08T07:28:43Z

Created page with "Several sources of error make raw GPS measurements inaccurate. To make up for this, consumer GPS receivers use a "model" to help determine what part of the measurement is erro..."

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Several sources of error make raw GPS measurements inaccurate. To make up for this, consumer GPS receivers use a "model" to help determine what part of the measurement is error. Basically, the model tells the receiver what kind of motion it can expect. If a measurement indicates motion that doesn't fit the model, then the receiver assumes it must be noise, and ignores it.

In many consumer GPS receivers, the model is presented as a choice between "car" and "pedestrian" modes. In the FlySight, a few more choices are available, and it's not too hard to guess what kind of motion each might assume:

{|border="1" cellpadding="3" cellspacing="0" align="center"
|-
|'''Model'''
|'''Expected motion'''
|-
|Portable
|Unknown
|-
|Stationary
|No motion
|-
|Pedestrian
|Slow, mostly horizontal motion
|-
|Automotive
|Fast, mostly horizontal motion
|-
|Sea
|Entirely horizontal motion
|-
|Airborne
|3D motion with limited acceleration
|}

It's important to understand the role the model plays. For example, if you set the FlySight to use the "Pedestrian" model, and then you jump from a plane, it will try to reconcile your rapid descent with its idea of how a pedestrian moves.

Less obviously, if you tell the FlySight to use the "Airborne < 1G" model, and then you perform a maneuver which results in more than 1G acceleration, the FlySight will "overshoot", because it chalks some of that acceleration up to noise.

When flying a wingsuit, we recommend the "Airborne < 1G" model. For swoopers, we recommend the "Airborne < 2G" model", since high performance landings can generate more than 1G acceleration.

Data models - Revision history

WikiSysop: Created page with "Several sources of error make raw GPS measurements inaccurate. To make up for this, consumer GPS receivers use a "model" to help determine what part of the measurement is erro..."