because convolution in Time domain become to production in frequency domain, i.e.
H(f)=H1(f)*H2(f)
then the spectrum is the production of a constant (AWGN spectrum) in raised cosine spectrum.
because convolution in Time domain become to production in frequency domain, i.e.
H(f)=H1(f)*H2(f)
then the spectrum is the production of a constant (AWGN spectrum) in raised cosine spectrum.