import math


def fnCalculate_Bistatic_Doppler_Resolution(wavelength,t_cpi,bis_angle):
	"""
	Calculates the bistatic Doppler resolution corresponding to a given bistatic angle,
	given the CPi length in seconds of the radar system.
	
	Equation 7.5b on page 134 in Willis: Bistatic Radar
	
	Created on: 17 April 2017
	"""
	doppler_resolution = wavelength/(2.*t_cpi*math.cos(bis_angle*0.5));
	return doppler_resolution