Vetta V100A Manual page 39

PERCENT GRADE
VETTA uses a barometric sensor to gauge the (noise) changes in
the air pressure which does not update constantly; this is why
sometimes you may get varying readings due to weather
changes, fast ascents and descents or not enough change in
altitude i.e. small rolling hills.
These are some of the other guidelines you can use to improve
the accuracy of readings.
• It will take at least a 20-30m distance (depending on the
pressure sensor) before it starts to output a gradient reading
even for steep slope (say over 10%).
• It will output a gradient reading of a slope which vertical
displacement is larger than 3-5m. i.e. it will display zero
gradient if the vertical displacement of the short slope is less
than 3m in height.
• For the same reason as above, the V100A may display zero or
higher gradients; if the user climbs a short slope followed by
descending another short slope.
• If you are looking for what we call a real-time altimeter, the most
accurate way is GPS. Otherwise most altimeters use a very
sensitive pressure sensor that measures the changes in the air
pressure.