Satmap active12 Guide de l'utilisateur télécharger pdf (Page 33)

© Satmap Systems Ltd

© Satmap Systems Ltd 2014

33

6. MAIN MENU: Settings Menu (... cont)

6.5 Elevation

(MAIN MENU / Settings /Elevation)

Overview. The Active 12 gives you

3 options for calculating elevation

values. All are useful, but they do

have some pros and cons.

Elevation from Maps. Each map

is supplied with a "height data set"

that provides spot heights at regular

horizontal intervals (post spacing).

Typically these are between

50m-100m. This method works well

when the ground is less steep, with

fewer cliffs around.

Elevation from GPS. This method

uses height data supplied by the

GPS itself, and works best when

there is a good, unobstructed view of

a large portion of the sky. The data

can be quite variable in forests and

amongst tall buildings.

Elevation from Pressure. The

highly accurate barometric altimeter

can be used to assist with elevation

calculations, and uses the principle

that pressure falls as elevation rises.

It is especially useful over short

periods of time where the weather is

relatively stable, since pressure also

generally falls when bad weather is

approaching.

Setting "Elevation" source. Data

that is stored for later upload has a

single set of elevation data. You can

control this by setting its source.

Select Elevation from the SETTINGS

screen. The top box indicates the

Elevation data source and can be

changed by moving the joystick left

and right (when it is highlighted by

the orange background). A selection

can be made between "Elevation

from Maps, GPS or Pressure". The

rst two settings require no further

action - just press Done, Back or Map

to continue with the GPS use.

Setting Elevation from Pressure.

To work effectively, elevation from

the barometric altimeter needs to

be calibrated at intervals. This is

because changing weather would

otherwise affect the elevation

reading.

Altimeter Calibration: Auto. On this

setting the Altimeter is recalibrated

against the Map elevation every 2

hours (by default). This is a good

setting for normal use and requires

no further user input.

Info Box:

"Last Successful Calibration." If

a long time has elapsed since the

last calibration, the accuracy may

have drifted due to weather change:

Select "Elevation" from SETTINGS

Select Elevation data source

Select Recalibration frequency

Auto calibration setting

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