VTP2VLLA

MATLAB

Vlla = VTP2VLLA(h,x,G,Vtp,[Vmag],[upDir],[outType],coordBase)

Description

Converts velocity in the target TP coordinate frame defined in a plane perpendicular to the propagation to an LLA velocity based on the platform and target locations. Can specify an alternate vector for projection of the zenith onto the plane perpendicular to the propagation, upDir, for an arbitrary rotation of the TP coordinate frame. One can also specify that the platform be used as the basis for the TP coordinate frame. This option should be used if the user wants to analyze the reverse geometry but does not want to change the relationship between TP/XY and the propagation direction.

Parameters

Parameters	Description
h [vector]	Altitude above mean sea level (m)
x [vector]	Normalized screen locations
G [struct]	Geometry structure from GeomStruct
Vtp [vector]	Velocity in TP coordinates (m/s). The size is either 1x2 for a constant TP velocity along the path or NScreensx2 to vary TP velocity along the path
Vmag [scalar]	(Optional) Magnitude for the velocity. If not specified, magnitude will be equal to that of Vtp
upDir [vector]	(Optional) Projection of the zenith onto the plane perpendicular to the propagation direction. Defaults to zenith projection in the target TP coordinates
outType [string]	(Optional) Indicates the output. Either 'horizontal' for only horizontal speed, 'heading' for heading, or 'vertical' for vertical speed. If not input, the output is an LLA velocity vector.
coordBase [string]	(Optional) Specify 'P' to use the platform as the base for the TP coordinates. Defaults to target-based coordinates

Return Values

Return Values	Description
Wlla [array]	LLA velocity vector or speed/heading based on outType.

Examples

>> S = EngagementStruct(GeomStruct('Simple',1000,10000,100000, ...

100,10,90,0));

>> VTLLA = VTP2VLLA(S.ht,1,S.G,[0 S.V_TTP],S.vt);

Returns the LLA velocity vector for the target

>> Atm = AtmStruct(S.G,10);

>> Wlla = VTP2VLLA(Atm.h,Atm.z/Atm.L,S.G,[5 0]);

Returns an LLA velocity vector for natural wind along the path

>> Atm = AtmStruct(S.G,10, ...

'Wind','VTP2VLLA','x','G',[5 0],5,[],'horizontal', ...

'WindHeading','VTP2VLLA','x','G',[5 0],5,[],'heading', ...

'VerticalWind','VTP2VLLA','x','G',[5 0],5,[],'vertical')

Computes an Atm structure with a 5 m/s wind perpendicular to the propagation direction and perpendicular to the target motion