# The usage of Matlab function downsample

(I) Downsample
Reduce the sampling rate by an integer multiple

syntax
y =downsample (x, n)
y =downsample (x, n, phase) y =downsample (x, n) reduces the sampling rate of x by retaining the first sample and then the NTH sample after the first sample. If x is a matrix, the function treats each column as a separate sequence. Y = Downsample (x, n, phase) specifies the number of samples for the sampling sequence under offset. Example 1:
reduces the sampling rate of the sequence by a factor of 3. x = [1 2 3 4 5 6 7 8 9 10];
y =downsample (x, 3)
y = 1×4 1 4 7 10 example 2: reduce the sampling rate of the sequence by 3 times and increase the phase offset by 2. That is to offset two Numbers backward from the first number for downsampling y =downsample (x, 3, 2)
y = 1×3 3 6 9
x1 = [1 2 3 4 5 6 7 8 9];
y =downsample(x1,3,1) y = 2 5 8
example 3:
reduces the sampling rate of the matrix by 3 times. X = [1 2 3;
4 5 6;
7 8 9;
10, 11 12];
y =downsample (x, 3)
y = 2×3 12 3
10 11 12 input parameters
x — input array
vector | matrix
input array, specified as a vector or matrix. If x is a matrix, the function treats the columns as independent channels. Example: Cosine (PI/4 * (0:15 9)) + RANDn (1,160) specifies the sine curve plus the White Gaussian noise. Example: cos (PI./ [4; 2] * (0:15 9)) ‘+ randn (160,2) specifies a two-channel sine wave. Data type: single | double
complex number support: is
n – down sampling coefficient
positive integer
under sampling factor, specified as a positive integer. Data type: single | double
phase – offset
(default) | positive integer
offset, specified as a positive integer between 0 and n-1. Data type: single | double output parameter
y – down sampling array
vector | matrix
down sampling array, returned as a vector or matrix.