Questions tagged [resampling]

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30
votes
7answers
23k views

What is an algorithm to re-sample from a variable rate to a fixed rate?

I have a sensor that reports its readings with a time stamp and a value. However, it does not generate readings at a fixed rate. I find the variable rate data difficult to deal with. Most filters ...
14
votes
3answers
14k views

How to Resample Audio Using FFT or DFT

I'm down sampling voice audio by first performing an FFT, then only taking the parts of the result that I need, and then performing an inverse FFT. However, it's only working properly when I'm using ...
5
votes
3answers
586 views

Absolute convergence of periodic sinc interpolation

An $N$-periodic complex discrete-time sequence $[x_0, \dots, x_{N-1}]$ can be resampled to an $M$-periodic sequence $[y_0, \dots, y_{M-1}]$ with $M>N$, using sinc interpolation: $$\begin{align}y_m ...
3
votes
1answer
619 views

Frequency Representation of Downsampled Signal

I'm trying to follow the steps from Oppenheim for the derivation of the frequency representation of a signal which is to be down sampled by a factor of M. It makes sense to me that: But then the ...
2
votes
3answers
1k views

Resampling and removing high frequency noise?

I am currently working on a simple sampler that will allow me to load in a wav file and use my MIDI keyboard to play the loaded wav sample at the frequency according to the note played. Now I need ...
5
votes
4answers
8k views

How Can I Resample a Signal with an Arbitrary Factor (For Example - 128000Hz to 16000.1Hz) in MATLAB?

I need to simulate the sampling of a continuous (fsCtu = 128000Hz), acoustic signal with two microphones that have a slight offset in sampling rate (fsMic1 = 16000, fsMic2 = 16000.1) in Matlab. What ...
1
vote
1answer
1k views

The condition in order to not lose information after upsampling and downsampling [closed]

If you have a signal x[n] and it is interpolated by N and then decimated by M, how do you ensure minimum distortion in x[n] from the resampling process?
10
votes
1answer
6k views

Python's $\tt resample$ vs $\tt resample\_poly$ vs $\tt decimate$

I have multiple signals each measured with a sampling rate 300Hz. They are mostly periodic, although there are some parts of some of the signals, that seem to be random and do not follow the rest of ...
2
votes
2answers
3k views

Resampling of signal with non uniform sampling frequency

I have a non uniform sampling frequency signal and I have to convert it in a constant sampling frequency. I tried to interpolate it with an Hermite spline interpolation but it make a lot of wrong ...
4
votes
2answers
17k views

What is the difference between cubic interpolation and cubic “Spline” interpolation?. How to use it for upsampling purpose?

After considering a couple of advices and suggestions for upsampling techniques here, I finally converged to use the cubic interpolation technique to estimate the voltage values corresponding to ...
14
votes
5answers
14k views

what is better: up- or downsampling?

I want to compare two signals or curves. Unfortunately they have different sample rates. The first one is sampled at 30 Hz, the second at 2000 Hz. Matlab has the function 'resample' and I thought, ...
12
votes
3answers
11k views

What are the relative merits of various upsampling schemes?

I recently encountered a DSP system which did some internal upsampling via zero padding. Expecting zero-order-hold, I was surprised to find that a DC signal did not produce a DC output; many ...
2
votes
0answers
78 views

Compensate for residual resampling error with a quadratic phase vs frequency- possible?

With regards to the answer in this post Is it possible to do deconvolution with two data sets that have different sampling rates? I suggest the possibility of compensating for a residual resampling ...
4
votes
1answer
4k views

Upsample data using FFTs. How is this exactly done?

I am basing my question on this post here, because I would like additional details on it, as I have not had any success in re-creating it. I would like to simply learn, in no uncertain terms, how to ...
3
votes
2answers
572 views

Ripple in time-domain using lanczos resampling

I'm seeing ripple in the time domain when resampling a "unity signal", that is, all ones, with lanczos filters. The ripple/error exactly resembles a cosine with a period of the sampling rate - ie. the ...
2
votes
3answers
803 views

Splitting the Unit Delay

Please refer to the paper Splitting the Unit Delay - Tools for fractional delay filter design by Laakso, Valimaki et.al. I am not able to visualize how the fractional delay is obtained by resampling ...
2
votes
1answer
267 views

How to implement sinc interpolation

I'm trying to write my own high quality audio sample rate converter. I barely know anything about signal processing though so I need help. From what I understand I need to sum together normalized sinc ...
2
votes
2answers
1k views

Resampling a digital sound signal

As a non maths-pro, I'm looking for some pointers. I am rewriting the audio core in my emulator to improve accuracy, and am getting a bit stuck on the specifics of the technique. I am trying to ...
1
vote
2answers
124 views

Fourier Transform of sampled reflectance measurements

Goal: Calculate the complex index of refraction ($\hat n = n +jk)$ from reflectance measurements. Data: Reflectance measurements for various materials were taken with a FTIR (Nicolet™ iS50 FTIR, ...
1
vote
1answer
1k views

Computational Complexity of Polyphase Resampling

does someone know the approximate computational complexity of a polyphase resampling algorithm? I am trying to find a good argument to prefer a polyphase resampling of Scipy over the FFT resampling ...
0
votes
3answers
40 views

Theoretical considerations for Using Finite Arrays to Represent Samples of Signals of Infinite Length

Discrete signals can come from sampling continuous-time signals. A continuous-time signal can be of infinite support. For instance, a sin wave. In terms of mathematical description of signals and ...
0
votes
1answer
402 views

Resampling scattered data with MATLAB's $\tt interp$ and $\tt resample$

I am recording acceleration data with an MPU6050 connected to a Arduino1 and stored on a SD. Here you can find the code. I need to calculate the FFT of an acceleration signal that was not sampled ...
0
votes
3answers
1k views

Which anti aliasing filter algorithm for efficient audio resampling?

I'm building a real-time audio resampler (think pitch bend) that needs to have a several different performance vs quality configuration options. I understand that I'll need to apply a low-pass filter ...
0
votes
2answers
287 views

What are the implications of resampling the derivative of a signal with a higher frequency than the original signal?

Suppose I have a digital signal measured with sampling time, $T_s=1$ sec. If I take it's derivative, it will, naturally have $T_s=1$ sec. But what are the implications if I re-sample this derivative ...
0
votes
1answer
133 views

Upsampling question- Aliasing/imaging problem

I'm trying to study vibrations in a non-stationary shaft by upsampling the original signal. The original sample rate is at 25.6kHz, and it is being upsampled to 36kHz. In the FFT of the upsampled ...
0
votes
3answers
200 views

Various size arrays interpolation - resampling

sorry if it's stupid question but it’s third day that I try to figure it out how to do that. And just can’t find the solution. Let’s say I have array $A$ size 4, and $B$ size 8. And I need to put/...