write a python script for generating the transmitted BPSK $($Binary Phase shift Keying$)$ of $1023$ bits for space vehicle $20.$with PRN code $[4,7].$ The digital output is all $1$s and $0$s$.$ However when transmitted with BPSK all of the $1$s become $1$s and all of the $0$s become $-1$s$.$ The construction of G$1,$ G$2$ and the taps used for each space vehicle are as followed:

# Define the shift and PRN functions as before

def shift$($register$,$ feedback, output$)$:

out $=[$register$[$i$-1]$ for i in output$]$

if len$($out$)>1$:

out $=$ sum$($out$)\%2$

else:

out $=$ out$[0]$

fb $=$ sum$([$register$[$i$-1]$ for i in feedback$])\%2$

for i in reversed$($range$($len$($register$[1$:$])))$:

register$[$i$+1]=$ register$[$i$]$

register$[0]=$ fb

return out

def PRN$($sv$)$:

G$1=[1$ for i in range$(10)]$

G$2=[1$ for i in range$(10)]$

ca $=[]$

for i in range$(1023)$:

g$1=$ shift$($G$1,[3,10],[10])$

g$2=$ shift$($G$2,[2,3,6,8,9,10],$ sv$)$

ca$.$append$(2*(($g$1+$ g$2)\%2)-1)$

# Generate the PRN code for the chosen space vehicle $($e$.$g$.,$ SV$20)$

sv$\_$prn $=$ PRN$([4,7])$ # Using SV$20$ as an example