# [EE - Signals] Question about Discrete-Time Impulse/Discrete-Time Delta

1. Aug 30, 2007

### user101

Quick question about a discrete unit impulse.

If I were to draw delta[n+1], at

... etc
n = -2 ... the point would be at location: 0
n = -1 ... the point would be at location: 1
n = 0 ... the point would be at location: 0
n = 1 ... the point would be at location: 0
n = 2 ... the point would be at location: 0
... etc

What I'm asking is that the line that I have in red... is that correct, with the shift of +1 to the left (an advance signal)?

The reason I'm saying it's -1 is because when n is -1, delta[-1+1] is delta[0] = 1.

Last edited: Aug 30, 2007
2. Aug 30, 2007

### learningphysics

Yes that's right... just like ordinary continuous function... f(x+a) is f(x) shifted a units to the left.

3. Aug 31, 2007

### user101

Thanks for the reply. Just to make sure, I would have a "1" dot for y where x = -1 then, correct?

4. Aug 31, 2007

### learningphysics

Yes, that would be correct but usually discrete time signals are as stem plots... ie a vertical line is drawn from the x-axis up to the dot (nothing is drawn when y=0)... eg:

http://en.wikibooks.org/wiki/Digital_Signal_Processing/Discrete_Data#Stem_Plots

So your plot would have a vertical line segment at n=-1 from the x-axis up to the dot at y=1.

5. Sep 1, 2007

### user101

Ok, great! Thanks
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