downsample (Signal Processing Toolbox)

Decrease sampling rate by integer factor

Syntax

y = downsample(x,n)
y = downsample(x,n,phase)

Description

y = downsample(x,n) decreases the sampling rate of x by keeping every n^th sample starting with the first sample. x can be a vector or a matrix. If x is a matrix, each column is considered a separate sequence.

y = downsample(x,n,phase) specifies the number of samples by which to offset the downsampled sequence. phase must be an integer from 0 to n-1.

Examples

Decrease the sampling rate of a sequence by 3:

x = [1 2 3 4 5 6 7 8 9 10];
y = downsample(x,3)
y =
    1    4    7    10

Decrease the sampling rate of the sequence by 3 and add a phase offset of 2:

y = downsample(x,3,2)
y =
    3    6    9

Decrease the sampling rate of a matrix by 3:

x = [1 2 3; 4 5 6; 7 8 9; 10 11 12];
y = downsample(x,3);
x,y
x =
    1    2    3
    4    5    6
    7    8    9
   10   11   12
y = 
    1    2   3
   10   11   12

See Also

decimate, interp, interp1, resample, spline, upfirdn, upsample

diric dpss