OUTLINE
1. Introduction
2. Theory
3. Example
4. Conclusion
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Introduction
Upsampling is the process of increasing sampling rate of discret-time signal.
Theory
Upsampling in the frequency domain
or 
Example
Upsampling rate D = 2
Here is the sampled signal.
Upsampling rate D = 2 is applied.
Low-Pass filter of cutoff π/2, gain 2 is applied.
Final upsampled signal
Conclusion
