In [3]:

    

from math import pi
import math
from ../
AMP_heading = pi/2 # rotation of AMP (radians from from due north)
M3_swath = [0,120] # minimum and maximum angles for target detection (in degrees)
point1 = [20,100] # range, bearing (degrees)
point2 = [21,105] # range, bearing (degrees)

target_velocity(point1, point2, AMP_heading, M3_swath = [0,120])


    

    
Out[3]:





[2.098226801466877, 0.232321352824482]

In [2]:

    

def target_velocity(target, AMP_heading, M3_swath = [0,120])

def velocity_between_two_points(point1, point2, AMP_heading, M3_swath = [0,120]):
    """
    Determines magnitude and direction of target trajectory (from point 1 to point 2)
    
    Inputs: 
    point 1, point 2 = points where target was detected, in list format [range, bearing in degrees]
    AMP_heading = heading of AMP, in radians from due north
    M3_swath = list containing minimum and maximum angle ( in degrees) for M3 target 
               detection. Default is 0 --> 120 degrees
    
    Outputs:
    vel = [velocity magnitude, velocity direction]
    """
    
    point1_cartesian = transform_NIMS_to_vector(point1, AMP_heading, M3_swath)
    point2_cartesian = transform_NIMS_to_vector(point2, AMP_heading, M3_swath)

    # subtract 2-1 to get velocity
    vel = [point2_cartesian[0] - point1_cartesian[0], point2_cartesian[1] - point1_cartesian[1]]

    # calculate magnitude and angle of velocity
    vel_angle = math.atan(vel[1]/vel[0])
    vel_mag = (vel[0]**2 + vel[1]**2)**1/2
    
    return([vel_mag, vel_angle])



def transform_NIMS_to_vector(point, AMP_heading, M3_swath):
    """
    Transform NIMS detection (in format [range, bearing in degrees]) to earth coordinates (East-North)
    
    Returns X-Y coordinates of point after transformation.
    """
    # convert target bearing tp radians, and shift such that zero degrees is center of swath
    point[1] = (point[1] - (M3_swath[1] - M3_swath[0])/2) * pi/180

    # convert bearing to angle from due N by subtracting AMP angle
    point[1] = point[1] - AMP_heading

    # get vector components for point 1 and 2
    point_cartesian = [point[0] * math.cos(point[1]), point[0] * math.sin(point[1])]
    
    return(point_cartesian)


    

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