If we correlate the received signal with any one of the two orthogonal

if-we-correlate-the-received-signal-with-any-one-of-the-two-orthogonal

If we correlate the received signal with any one of the two orthogonal function, the obtained inner product will be

A. In phase

B. Quadrature

C. Zero

D. Cannot be determined

This question was posed to me in an interview for job.

This question is from Modulation Techniques in division Modulation and Coding Trade-off of Digital Communications

Right answer is C. Zero

The explanation is: If we correlate the received signal with only one of the orthogonal function for example sine, the inner product obtained will be zero.