# Variable Sampling Frequency Interpolation-hrv

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gntrdm on 21 Apr 2015
Edited: Youssef Khmou on 27 Apr 2015
I have a "hrv" signal which has variable sampling frequency. How can I sampling this signal in 4Hz(250ms) without using "interp1" function, only use linear interpolation. My hrv is like that: [ 600 720 780 750 610 640 710 750 690 620 640 700 745 710 670 ].
Have a nice day
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Star Strider on 27 Apr 2015
Are your data R-R intervals? (I suspect they are.)
I don’t understand that you would want to interpolate them. Just use the R-R intervals (likely in milliseconds) that you have and analyse those. (I might add that you need considerably more than you posted for adequate determination of HRV. Ideally, you need at least 24 hours of data.)

gntrdm on 27 Apr 2015
Any idea?

Youssef Khmou on 27 Apr 2015
Edited: Youssef Khmou on 27 Apr 2015
An alternative solution exists using resample(x,p,q) function where the new signal is sampled with p/q times the original sampling frequency, p and q must be integers, here is an example :
y=sin(2*pi*1.5*(0:0.1:10));
y is R^[1x101] with fs=10 Hz, if we want five times the original sampling frequency, say 50Hz :
z=resample(y,10,2);