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I've a little question regarding interpolation in GNU Radio: I'd like to do an interpolation (by a factor of 2) and be able to change the sampling period of the samples interpolated but im having a hard time trying to do it, does someone has any idea on how to do it in GNU Radio ?

As im very knew to this, here is a little picture of what I'm trying to do.

:enter image description here

In orange my samples and in blue my samples interpolated with a different period (the aim is that I can "move" the blue samples to be closer or farther to the orange samples).

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  • $\begingroup$ There's no such thing as "sampling period" from the perspective of GNU Radio. Every sample is just a number. Information about "rate" or "period" is not relevant to what GNU Radio does to the samples. To interpolate, you can either use a low-pass filter with the "interpolating FIR filter" block, or just use the "rational resampler" block with an interpolation of 2. $\endgroup$
    – Marcus Müller
    Jul 4, 2022 at 10:55
  • $\begingroup$ yep, the picture really is likle the textbook picture of "you need a resampler", but there's no factor of 2 as you state in your question $\endgroup$
    – Marcus Müller
    Jul 4, 2022 at 21:14
  • $\begingroup$ Well, thank you very much for your time Marcus! If there is no such thing as sampling period in GNU Radio, could it be possible to include a block doing a sort of delay between two samples (or even just a delay for the samples interpolated) that i can dynamically change(=like a block range)? Thank again :) $\endgroup$
    – Tyra
    Jul 5, 2022 at 9:07
  • $\begingroup$ that's a fractional delay, there's a block with that name. $\endgroup$
    – Marcus Müller
    Jul 5, 2022 at 15:27

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There's no such thing as "sampling period" from the perspective of GNU Radio. Every sample is just a number. Information about "rate" or "period" is not relevant to what GNU Radio does to the samples. To interpolate, you can either use a low-pass filter with the "interpolating FIR filter" block, or just use the "rational resampler" block with an interpolation of 2.

As a matter of fact, the official GNU Radio tutorials have a chapter on "Sample Rate Changes"! Since you've not found that yet, it seems you haven't done the tutorials; it's probably some very well-invested time you'd spent reading these, as you'll be much quicker doing GNU Radio stuff yourself afterwards!

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