Function Reference: interp

Function File: y = interp (x, q) ¶

Function File: y = interp (x, q, n) ¶

Function File: y = interp (x, q, n, Wc) ¶

Upsample the signal x by a factor of q, using an order 2*q*n+1 FIR filter. Note that q must be an integer for this rate change method. n defaults to 4 and Wc defaults to 0.5.

Example

# Generate a signal.
t=0:0.01:2; x=chirp(t,2,.5,10,'quadratic')+sin(2*pi*t*0.4);
y = interp(x(1:4:length(x)),4,4,1);   # interpolate a sub-sample
stem(t(1:121)*1000,x(1:121),"-g;Original;"); hold on;
stem(t(1:121)*1000,y(1:121),"-r;Interpolated;");
stem(t(1:4:121)*1000,x(1:4:121),"-b;Subsampled;"); hold off;

See also: decimate, resample.

Demonstration 1

The following code

 ## Generate a signal.
 t=0:0.01:2; x=chirp(t,2,.5,10,'quadratic')+sin(2*pi*t*0.4);
 y = interp(x(1:4:length(x)),4,4,1);   # interpolate a sub-sample
 plot(t(1:121)*1000,y(1:121),"r-+;Interpolated;"); hold on;
 stem(t(1:4:121)*1000,x(1:4:121),"ob;Original;"); hold off;

 % graph shows interpolated signal following through the
 % sample points of the original signal.

Produces the following figure

Figure 1

Package: signal