satmap active12 - Elevation

Software v3.0.9915
© Satmap Systems Ltd 2015
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6. MAIN MENU: Settings Menu (... cont)
6.6 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 first
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: it would be wise
to recalibrate the device as described
below.
Auto Recalibrate Frequency. The
left / right joystick function can be used
to toggle the recalibrate time interval
between 2 / 4 / 6 / 8 hours.
"Calibrate Now" button will calibrate
the local pressure against your current
Map Elevation, and record the date and
time for future reference.
Manual Calibration. Should you wish
to have more control over the recalibration
of the altimeter, select "Manual" using the
joystick, and then Select
.
Method 1: Map/GPS Elevation. This
will simply use the Map elevation for
calibration (or GPS height data for no
map data is available).
Select "Elevation" from SETTINGS
Select Elevation data source
Select Recalibration frequency
Auto calibration setting