Trying to compress a signal.

Hi guys im trying to compress a signal

n is the time vector given by : n=[0 1 2 3 4 5 6 ] and xn is the vector with the values of the discrete sequence and is: xn=[0 1 2 3 4 1 0]

signal compression is "x(2*n)", x2n= [0 2 2 0 0 0 0] .

Is there any way to calculate these new points in matlab?

Thanks!

Answer 1

[Walter Roberson]

compressed_x = x(1:2:end);

[Rafael Ortiz]

Hey hi, thanks for your answer!

well, i'm learning the basics about signal processing and i'm not too experienced using matlab for that, so can you teach me how can i use this? i'm trying to find x*2n values.

[Walter Roberson]

n = [0 1 2 3 4 5 6] 

n = 1×7

0 1 2 3 4 5 6

x = [0 1 2 3 4 1 0]

x = 1×7

0 1 2 3 4 1 0

n2idx = @(n) n+1;
xn = @(n) x(n2idx(n))

xn = function_handle with value:
    @(n)x(n2idx(n))

x2n = @(n) x(n2idx(2*n));

xn(0:3)

ans = 1×4

0 1 2 3

x2n(0:3)

ans = 1×4

0 2 4 0

I have no idea why they think [0 2 2 0 0 0 0] would be an appropriate output. I could speculate that they might want 0 as the output after the "end" of x, but if so then I would expect an output of [0 2 4 0 0 0 0]

[Walter Roberson]

n=[0 1 2 3 2 1 0]

n = 1×7

0 1 2 3 2 1 0

x = [0 1 2 3 4 1 0]

x = 1×7

0 1 2 3 4 1 0

n2idx = @(n) n+1;
xn = @(n) x(n2idx(n))

xn = function_handle with value:
    @(n)x(n2idx(n))

x2n = @(n) x(n2idx(2*n));
xn(n)

ans = 1×7

0 1 2 3 2 1 0

x2n(n)

ans = 1×7

0 2 4 0 4 2 0

[Rafael Ortiz]

Thank you so much!

Answer 2

[Sulaymon Eshkabilov]

Have you read this help DOC: https://www.mathworks.com/help/signal/ug/dct-for-speech-signal-compression.html

that explains all steps of signal compression in a logical order.