Periodogram signal 1 Hz resolution using FFT

Hello everybody,

I am trying to compare two signal whit their frequency response. I've tried this code:

[P1,f1] = periodogram(original,flattopwin(length(original)),[1:fs/2],fs,'power');

I want to do the same (periodogram with 1 Hz resolution) using FFTs because I cannot coder this functions.

Thanks in advance,

Javier

Answer 1

[Eeshan Mitra]

Functions that are not supported by codegen can still be run in MATLAB from the generated code when "coder.extrinsic" is included in the function definition. Please find more information about using "coder.extrinsic" in the following documentation link:

https://www.mathworks.com/help/simulink/slref/coder.extrinsic.html

For example, lets assume the following simple function that is built for code generation for a signal x of size(1,1000), and a scalar sample rate:

 function [P1,f1] = pdgram (x,fs)
%#codegen
coder.extrinsic('periodogram');
[P1,f1] = periodogram(x,flattopwin(length(x)),[1:fs/2],fs,'power');

Generate code for this function using the following command:

>> codegen pdgram -args {zeros(1,1000,'double'),1000}

The difference is that the generated code calls MATLAB to access "periodogram".

However, if you want to perform the calculations for "periodogram" within the generated code using an "fft" implemention, please read more about its algorithm in the following documentation link:

https://www.mathworks.com/help/signal/ref/periodogram.html#btuc2ow-1

Note that Variable-sizing restrictions apply to the function "fft". Please find more information about Variable-sizing in the following documentation link:

https://www.mathworks.com/help/coder/ug/restrictions-on-variable-sizing-in-toolbox-functions-supported-for-code-generation.html