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.


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