Consider a CDMA system that uses $4$ chips per user. We have $2$ userts. User $1$ sends $"5"$ as data and user $2$ sends $"7".$ We assign the following spreading codes to each user:

C$1$: $[1$

a$)$ Are the codes orthogonal? Justify your answer. $(10)$

b$)$ Obtain the RX vector. Name it vector A$.(10)$

c$)$ Show how User $2$ can extract its data from vector A$.(10)$