def fnCalculate_Bistatic_RangeRate(speed_light,tau_u1,tau_d1,tau_u2,tau_d2,tc):
	"""
	Calculate the average range rate. eqn 6.37 in Montenbruck 2000.
	tc =  length of integration interval, i.e. length of CPI
	Created: 04/04/17
	"""
	range_rate = (speed_light/tc)*(tau_u2+tau_d2-tau_u1-tau_d1); # removed 0.5 factor. 19.04.17
	return range_rate