explain inverse discrete-time fourier transform1

Question

Explain Inverse Discrete-Time Fourier Transform

1. Observe the same things among this formula and the inverse analogue Fourier transform:

• The (1/2π) factor
• The sign of j?n (n replaces t) that is "+"for the inverse DTFT and was "-" for the DTFT
• The variable of integration (d?)

2. The range of integration is just now -π to π rather than -∞ to ∞. (π corresponds to half the sampling frequency).

3. Negative frequencies are once again included.

4. With the DTFT, the forward transform is a summation and the inverse transform is an integral. This is because {h[n]} is a sequence whereas H(e^j?) is a function of the continuous variable ?.