Electronics and Communication Engineering - Signals and Systems - Discussion

Discussion Forum : Signals and Systems - Section 3 (Q.No. 16)
16.
Which one is a non-causal system?
y(n) = x(2n)
y(n) = x(n/2)
y(n) = x(n/2) + x(n)
all
Answer: Option
Explanation:

Because in (a) if you put n = 1 then y(n) = x(2) which shows output depend upon future value.

While in (b), (c) input converted to Past or Present and past.

Note that n cannot be in fraction so for x(n/2) you will put n = 2, 4, ... etc. not 1, 3, 5 .... etc.

Discussion:
2 comments Page 1 of 1.

Nitin said:   1 decade ago
In b and c, if you put n=-2 then output will be depends on n=-1 as x(-2/2) = x(-1).

Which is future value so all are non causal systems?

Midhun Joy said:   3 years ago
I think it should be option D.

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