i need a little help w/ my ECE 301 hwk.

M=16 (samples taken)

S[m]= impulse(m-1)+ impulse(m-15). Find S[k]



i used the formula Summation: Impulse(m-1) *e^(-j2(pi)*k*(n/M)) where n is the offset 1 and 15.

therefore getting S[k]= e^(-j2(pi)*k*(1/16))+ e^(-j2(pi)*k*(15/16)) . Did i do this correctly??

I always have trouble figuring out how to transform offset impules in the t domain into F or S domain and vice versa.

7/23/2006 11:35:56 PM

I hope this shit ain't on the PE!

7/24/2006 6:35:08 AM

you're kidding right?

that's about one of the easiest DFT questions you can get..

think two exponentials w/ complementary frequencies = cosine

[Edited on July 24, 2006 at 6:28 PM. Reason : esp]

7/24/2006 6:27:25 PM

i thought for it to be cosine u need an equal impulse on opposite sides of the frequency spectrum. one being negative the other positive.

7/24/2006 9:51:37 PM

Remember a negative angle is equivalent to some positive angle and vice versa. So if you had
e^(-j(1/4)pi) + e^(-j(7/4)pi), you can say e^(-j(7/4)pi) = e^(j(1/4)pi), then you have it in the right form to convert to a cosine.

7/24/2006 10:02:39 PM

i don't remember any of this

7/26/2006 12:32:38 AM