Can you tell me whether the following signal is a energy or power signal? $$ x(n) = e^{j (n \pi/2 + \pi/8) } $$ I've solved it and found it as it was neither power nor energy signal was that right?

  • 2
    $\begingroup$ Can you show the work you did to arrive at your conclusion? I think this would be helpful in supplying an appropriate answer to your question. $\endgroup$
    – user2718
    Commented May 31, 2013 at 12:32

1 Answer 1


The energy of a discrete-time signal is defined as


and its power is given by


With $x(n) = e^{j (n \pi/2 + \pi/8) }$ we have $|x(n)|^2=1$ which implies that the sum in (1) does not converge, i.e. $x(n)$ has infinite energy. For the power we get


The signal $x(n)$ has finite power and is consequently a "power signal".


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