Vertical Speed Indicator
A software variometer.
On this screenshot, the indicated rate of descent is 1.6 m/s.
This application calculates vertical speed estimation using simple linear regression. More details here.
Sample size can be configured in the settings window. Long sample size makes better climb/descent rate estimation from the noisy sensor reading, but causes longer lag. Experiments show that default sample size 128 effectively detects climb/descent rate 0.1 m/s, with about 8 seconds lag on "fast" sensor rate.
Supported speed units: