IMPLEMENTATION OF UPSAMPLING & DOWNSAMPLING

The process of converting the sampling rate of a digital signal from one rate to another is Sampling Rate Conversion. Increasing the rate of already sampled signal is Upsampling whereas decreasing the rate is called downsampling.
The purpose of Upsampling is to manipulate a signal in order to artificially increase the sampling rate.
To make a digital audio signal smaller by lowering its sampling rate or sample size (bits per sample). Downsampling is done to decrease the bit rate when transmitting over a limited bandwidth or to convert to a more limited audio format.
It depends on the level of certainty you need. If you don't need mathematical certainty and just want a heuristic, downsampling is faster and upsampling is more accurate.

1. SUBMITTED BY FAIZAN SHAFI [21304012] ECENG-522 [ADSP] M.Tech (ECE)- Ist year SUBMITTED TO Dr. K. ANUSUDHA ASSISTANT PROFESSOR Dept. Of Electronics Engineering SIMULATION O N “ IMPLEMENTATION OF UPSAMPLING & DOWNSAMPLING " D EPARTMENT OF ELECTRONICS ENGINEERING SCHOOL OF ENGINEERING AND TECHNOLOGY PONDICHERRY UNIVERSITY,KALAPET, PUDUCHERRY-605014  

2. CONTENTS INTRODUCTION WHAT IS UPSAMPLING & DOWNSAMPLING USED FOR DIFFERENCE BETWEEN UPSAMPLING & DOWNSAMPLING SIMULATED DIAGRAM OUTPUTS SOFTWARE USED REFERENCES   2

3. INTRODUCTION UPSAMPLING :- In  digital signal processing,   upsampling , expansion , and  interpolation  are terms associated with the process of  resampling  in a  multi-rate digital signal processing  system.  Upsampling  can be synonymous with  expansion , or it can describe an entire process of  expansion  and filtering (interpolation). When upsampling is performed on a sequence of samples of a  signal  or other continuous function, it produces an approximation of the sequence that would have been obtained by sampling the signal at a higher rate (or  density , as in the case of a photograph). For example, if  compact disc audio at 44,100 samples/second is upsampled by a factor of 5/4, the resulting sample-rate is 55,125. Upsampling is  the process of inserting zero-valued samples between original samples to increase the sampling rate . (This is sometimes called “zero-stuffing”.) This kind of upsampling adds undesired spectral images to the original signal, which are centered on multiples of the original sampling rate. 3

4. INTRODUCTION DOWNSAMPLING :- In  digital signal processing,   downsampling ,  compression , and  decimation  are terms associated with the process of  resampling  in a  multi-rate digital signal processing system. Both downsampling and decimation can be synonymous with compression, or they can describe an entire process of bandwidth reduction ( filtering ) and sample-rate reduction. When the process is performed on a sequence of samples of a signal or a continuous function, it produces an approximation of the sequence that would have been obtained by sampling the signal at a lower rate. Decimation is a term that historically means the  removal of every tenth one.  But in signal processing, decimation by a factor of 10 actually means keeping only every tenth sample. This factor multiplies the sampling interval or, equivalently, divides the sampling rate. For example, if  compact disc audio at 44,100 samples/second is decimated by a factor of 5/4, the resulting sample rate is 35,280. A system component that performs decimation is called a decimator. Decimation by an integer factor is also called compression. 4

5. WHAT IS UPSAMPLING & DOWNSAMPLING USED FOR T he process of converting the sampling rate of a digital signal from one rate to another is Sampling Rate Conversion.  Increasing the rate of already sampled signal is Upsampling whereas decreasing the rate is called downsampling . The purpose of Upsampling is  to manipulate a signal in order to artificially increase the sampling rate . To make a digital audio signal smaller by lowering its sampling rate or sample size (bits per sample) . Downsampling is done to decrease the bit rate when transmitting over a limited bandwidth or to convert to a more limited audio format. It depends on the level of certainty you need. If you don't need mathematical certainty and just want a heuristic,  downsampling is faster and upsampling is more accurate . 5

6. DIFFERENCE BETWEEN UPSAMPLING & DOWNSAMPLING Downsampling, which is also sometimes called decimation, reduces the sampling rate. Upsampling, or interpolation, increases the sampling rate. The Down sampling process is also called  decimation . The Up Sampling process is also called interpolation. 6

7. SIMULATED DIAGRAM 7

8. OUTPUTS 8

9. ORIGINAL SIGNAL 9

10. UPSAMPLED OUTPUT 10

11. FILTERED OUTPUT 11

12. DOWNSAMPLED OUTPUT 12

13. SOFTWARE USED   MATLAB [SIMULINK] 13

14. REFERENCES https://en.wikipedia.org/wiki/Upsampling#:~:text=Upsampling%20requires%20a%20lowpass%20filter,of%20the%20two%20cutoff%20frequencies https://en.wikipedia.org/wiki/Downsampling_(signal_processing) https://www.dsprelated.com/freebooks/sasp/Upsampling_Downsampling.html https://www.sweetwater.com/insync/upsampling/ 14

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