Matlab HRV frequency domain analysis using pburg and pwelch function

Question

i am doing HRV analysis and i've ran into a problem. I have sets of RR interval (about 100-160 in each) for example RR=[726 679 687 655 719 632 1071 978] etc, there are about 100-160 values in each RR. Now i need to do frequency analysis using function pburg and pwelch and then spliting the PSD from these functions into frequency bands (LF = 0.03 - 0.86 Hz; HF = 0.86 - 1.91 Hz). My sampling frequency is 2000.

So far that part of my code looks like this:

[Pxx1,w1]=pburg(RR,16,256,2000);
[Pxx2,w2]=pwelch(RR);

This function returns PSD on y-axis and frequency (0-1kHz) on x-axis. I just cant figure out how to evaulate PSD in these frequency bands (I need 0.03 - 0.86 Hz and x-axis is 0-1kHz, which seems extreme). After that i need probably itegrate the space under that curve somehow?

I i would figure pburg second thing is i dont know what input arguments should i input into pwelch.

Answer 1

If I am correctly getting you, you want to find the PSD within a specified frequency range.

If my assumption is correct, you can do the following.

%[Pxx,W] = PWELCH(double(data),window_length,overlap_size,[low_freq:high_freq], sampling_freq);

[Pxx,W] = PWELCH(double(RR), 512, 256, [30:860], 1000);

plot(W,(Pxx));

xlabel('Hz'); ylabel('Power');