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. In this slecture, I will discuss about how it works and example of upsampling.


Block.jpg

Theory
Upsampling in the frequency domain. It can be obtain in two different ways.

  Theroy.jpg       or           CodeCogsEqn.jpg


Example

Upsampling rate D = 2


Here is the example of sampling signal.

Graphex.jpg

Upsampling rate D = 2 is applied.

Graphex2.jpg

Low-Pass filter of cutoff π/2, gain 2 is applied.

Graphex3.jpg

Here is the final upsampling signal.

Graphex5.jpg

Conclusion

Upsampling by D inserts D - 1 zeros between every element of the original signal. Upsampling can create imaging artifacts. Lowpass filtering following upsampling can remove these imaging artifacts. In the time domain, lowpass filtering interpolates the zeros inserted by upsampling.


Questions and comments

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Sees the importance of signal filtering in medical imaging

Dhruv Lamba, BSEE2010