Vessel speed at pings algorithm

The Vessel speed at pings operator creates an echogram where the values of all samples within a ping are set to the speed of the vessel at that ping, in nautical miles per hour.

The speed at ping P is calculated from the two nearest GPS fixes as follows:

speed(P) = speed(AB)

where:

A	=	First GPS fix nearest to P where time(P) is in the range (time(A)...time(B)]*
		However, if A is the first GPS fix of the cruise track then time(P) = time(A).
B	=	Second consecutive GPS fix nearest to P
time(x)	=	The time of the ping or the GPS fix x
speed(AB)	=

*(x...y] indicates the interval from x to and including y; x is excluded.

See also

Vessel speed at pings operator