import math
from __future__ import division
#initialisation of variables
N=256; #no. of nodes
Lc=0.25; #loss per coup;er in dB
Power_margin=30; #power margin in dB
system_margin=6; #system margin in dB
Average_loss=0.6; #average loss in dB/Km
TxRX_powergain=32; #transmitter to receiver power gain in dB
Avg_Tr_loss=0.5; #average transmitter loss in dB/Km
#CALCULATIONS
Nc=math.log(N,2); #since 2x2 couplers are used
Ns=N/2; #each stage coupler
T_Nc=Nc*Ns; #total no. of couplers
Total_Lc=Nc*Lc; #total coupler loss in dB
Permissible_loss=TxRX_powergain-Total_Lc; #permissible cable loss in dB
L=Permissible_loss/Avg_Tr_loss; #Transmission distance in Km
#RESULTS
print"Transmission distance =",round(L,5),"Km";