This speedometer (velocimeter) calculates the speed by the distance and time moved horizontally.
Usage is simple: Enter the shortest distance to a target. Measure the shortest distance in advance with a rangefinder (e.g. Smart Distance, Smart Measure, Map).
Then, touch your screen following the target.
If the result is not accurate, you can calibrate your device with [Speed Calibration] option.
For more information, watch YouTube and visit the blog. Thank you.