RE: Interpolating signal from 4 sec to 1 sec

[William Krekeler]

 

 

From: address@hidden [mailto:address@hidden On Behalf Of Rick T
Sent: Friday, April 01, 2011 1:14 AM
To: address@hidden
Subject: Interpolating signal from 4 sec to 1 sec

 

Interpolating signal from 4 sec to 1 sec tia sal22 

 

Greetings All

 

I have a signal that cycles twice from 0 to 4 seconds  and

would like to interpolate the signal to cycle twice when

it goes from 0 to 1 second.  I know it's an issue with my xi

variable I'm just not sure how to fix it.

 

PS: the example is just a simple sine wave equation but I'll be importing an

audio wav file, that's why I chose to use interpolate 

 

%Interpolation test

clear all, clc,clf,tic

x= linspace(0,2*pi,400); %from 0 to 4 sec

fs_rate=100

freq=2;

y=sin(freq*(x)); 

 

xo=linspace(0,length(y)/fs_rate,length(y)); %go from 0 to x sec 

xi=linspace(0,1,length(y)); %go from 0 to 1 sec 

new_y=interp1(xo,y,xi,'linear');

subplot(2,2,1),plot(xo,y),title('Orginal signal over 4 sec')

subplot(2,2,3),plot(xi,new_y),title('Entire signal over 1 sec')

 

 

tia sal22 

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Not sure why you would only want to interpolate a portion of the signal as you would then have two different effective sample rates which will impact your ability to analyze the data. A quick interpolation method is the function spline.

 

Bill Krekeler