What is the algorithm to calculate ETA/ETE?

Yesterday Inused extensively. For example ETA showed 17pm as finish time. I stoped for 15 seconds to look around and ETA showed 2h more
So… what is the algorithm suunto uses to calculate ETA or ETE?

No one knows but I suppose it has something to do with average speed and distance left and direction
If you stop for a while ETA goes bananas as it doesn’t know where you’re heading (while avg speed is decreasing)

From the top of my head it’s using a 5 min rolling speed average.
That means remaining time is calculated as remaining distance divided by average speed of the last 5 mins.
If you stop the avg speed becomes slower and thus remaining time longer. 
thank you all