Interpolation is a method of constructing new data points within the range of a discrete set of known data points.

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FIR estimator for IIR system

Suppose that we have a dynamical system of which the impulse responses are infinite (IIR). Now I found methods on papers (http://dx.doi.org/10.1109/9.839942) estimating states or outputs of such a ...
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2answers
28 views

Interpolated impulse response for fraction delay?

I need to find a way to create some fractional delay in a signal processing application that I am working on. Separately to this, I have been messing around with basic filter design (despite reading ...
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1answer
31 views

Cut-off frequencies for fractional sample rate adjustment

We have a signal sampled att 22 kHz that we want to interpolate to 40 kHz. So we can do this by upsampling by a factor 20, then downsampling by a factor 11. My question regards the choice of cut-off ...
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1answer
58 views

Is there a relatively easy way to detect likely real-time peaks in discrete-time data?

Let's say I have a set of data over time, t: [0, 4, 6, 7, 7, 6, 4, 0] It seems likely that this data would peak at ...
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1answer
134 views

Why upsample before modulation?

We're doing a project in which we're sending an OFDM frame, modulated to some appropriate carrier, over a channel. Before modulating, we are instructed to upsample and low-pass it. Is there a good ...
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1answer
64 views

Fractional/Interpolating Delay Line still sounding glitchy

I'm trying to implement a simple digital delay line. I want it so that when the user changes the delay amount, it sounds smooth and not glitchy. Currently I'm implementing a fractional delay line but ...
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0answers
19 views

Type FIR LPF for Interpolation

I know this, input discrete function $$ x[n]= x0,x1,x2,x3 $$ then according to zero padding wtih $L=3$ my $z[n]$ will be $$ z[n]=x0,0,0,x1,0,0,x2,0,0,x3,0,0 $$ following this: ...
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0answers
17 views

Temporal Interpolation of Spectra

The signal of interest to me is the ocean wave height as a function of time at a particular location. Its power or variance spectrum is estimated by buoys at regular time intervals. Specifically, ...
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1answer
41 views

Resampling: how many samples to zero-stuff or down sample?

I am a little confused about how resampling works with one filter. I get why you choose the lower nyquist cutoff when you combine both interpolation and decimation for resampling by a rational ...
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1answer
33 views

Perform inverse distance weighting interpolation using multiple images matlab

I have a total of 4 highly identical grayscale images, where image1 is taken as the reference image, the rest of the images are to be used to enhance image1. My objective is to enlarge the image to 2 ...
2
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1answer
62 views

Practical vs ideal lowpass interpolator

Consider a signal with a sample rate $f_s = 44.1$ kHz. Let us upsample the signal by a factor of $L = 2$ and interpolate the zeros. An ideal lowpass interpolator would have a gain of $L$ and a cutoff ...
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3answers
92 views

Designing a 2x interpolation filter for audio

I want to perform 2x interpolation on an audio signal sampled at 44.1KHz by upsampling the signal by adding a zero after each original sample and then using a lowpass filter to interpolate the ...
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4answers
97 views

Basic method for 2x oversampling?

I would like to know if the following method of 2x oversampling is correct: Interpolate: Take an original signal sampled at 44100Hz as input Upsample by adding a zero after each original sample to ...
2
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1answer
80 views

Compute real signal from a discrete analytic signal

I have a 128MHz-wide down converted signal that gets processed in a FPGA via a polyphase filter bank to give 8x16 MHz baseband analytic signals. How do I convert this analytic signal to a real-valued ...
2
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1answer
35 views

Interpolate/Decimate with a single filter?

This is not a homework question (I'm out of school now 2 years). I'm thinking, let's say you have 2 systems, one at 32khz and the other at 48khz and you want to go between the two. Is there a way to ...
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0answers
33 views

Comparing AR coefficients derived from different sampling rates

I'm interested in comparing the coefficients of AR processes computed from different dynamic texture videos. That is, $A_1$ and $A_2$ are the $d \times d$ coefficients for dynamic texture videos 1 and ...
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2answers
71 views

Interpolation based on sinc function

I implemented an interpolation method in C++ based on this equation ...
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1answer
30 views

How to interpolate complex array (FT)?

I do Fourier Transform for an image, then consider line(slice) in FFT image. When that slice isn't parallel neither x- not y-axis, coordinates are not integer. E.g. slice can hold indices ...
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4answers
246 views

Estimate Delay of a Known Signal Delayed by Sub Sample Resolution

Given a known signal $ x \left( t \right) $ and its delayed version $ y \left(t, \tau \right) = x \left( t - \tau \right) $. Both are sampled by Sampling Frequency $ {F}_{s} $ to generate the signals ...
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4answers
135 views

Sampling Theorem illustration

Can someone please explain the illustration (figure 1.19) at the bottom of this image? It looks like there are four sampling points but I don't understand what the different curves represent. Actually ...
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1answer
37 views

Chosing polyphase interpolation coefficients

I'm writing code for a 3x polyphase interpolator using a total of 9 coefficients. This is organized as 3 parallel FIR branches with 3-taps each that are summed at the 3x sampling rate. The problem I ...
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0answers
26 views

How to reduce polynomial?

I have some 4 polynomials like this. these equation is made by polyfit() from MATLAB tool. ...
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2answers
36 views

Sinc interpolation looks weird

blue is how I tried to sinc interpolate. why would something like this happen?
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2answers
53 views

sinc interpolation using fft

Lets say I want to double the number of points in an array f. I had the idea to do this: F=fft(f);N=length(f); FF=[F(1:N/2) zeros(1,N) F(N/2+1:N)]; f=ifft(FF); ...
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1answer
53 views

Best way to approximate a curve?

I have a curve like this one: I need a function to approximate this curve, but I need that the function be a low order function (less than 5). What is a good way to obtain what I expect? Thanks!
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1answer
42 views

Is a cubic Lagrange interpolation tensor product the same as bicubic interpolation?

I just implemented some interpolated texture sampling by sampling the 4x4 nearest pixels then doing Lagrange interpolation across the x axis to get four values to use Lagrange interpolation on across ...
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0answers
19 views

How to shift with spline interpolation?

I have a sampled pulse shape: $ h = [1, 0.5]$ and I do not know what is its real underlying continuous-time pulse. I want to compute the samples of $h(t-\Delta t)$. If I write the continuous pulse ...
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0answers
70 views

Optimal signal sampling reduction method : Decimation, interpolation or both?

I have a function with an equation: \begin{equation} C(t)=1.6925\left(\exp^{-0.136t}- \exp^{-1.192t} \right) u(t) \end{equation} where u(t) is a unit-step function. Then, denoting the Fourier ...
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0answers
37 views

How to proceed with this convolution problem?

If $$\alpha_k = \sum_l a_l \ \ g((k-l)T-l\Delta T)$$ $$s_k = \sum_l \alpha_l \ \ q((k-l)T+k\Delta T)$$ where $a_l \in \pm1$ and $g(t) = \frac {\sin(\pi t/T)}{\pi t/T}$ and $q(t) = \frac {\sin(\pi ...
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0answers
33 views

Matlab Filter object for zero insertion interpolation

With Matlab we can model filter chains using filter objects. One type of filter object is the mfilt.holdinterp which performs sample and hold interpolation. Is there a way to create a zero insertion ...
3
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1answer
158 views

How to apply a Butterworth filter to data of varying sample rate?

I am trying to apply a Butterworth bandpass filter to accelerometer data of my smartphone. However, the accelerometer samples I receive do not come at regular intervals. Sample frequency varies ...
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0answers
117 views

How do I interpolate between bins on an FFT in python?

I have four frequency peaks, which I have after applying FFT. Now I want to know precise values of these frequency peaks. there are different interpolation methods. How can I use this method of ...
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1answer
35 views

linear interpolator replacement for the sinc function

How to find an optimum linear interpolator replacement for the ideal sinc function? The reason is for the hardware implementation ease. For example when I use sinc interpolation: ...
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2answers
106 views

How to compare the qualities of two interpolation (image resizing) algorithms?

I am implementing image resizing algorithms (Bilinear, Bicubic, Lanczos and a few others). How do I quantitatively compare them? I am thinking of considering a large sample of images and running ...
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2answers
221 views

Sinogram Fourier Analysis Doesn't Show Clear Bow Tie Shape

I'm working on finding the center of rotation of a set of test tomographic projections in order to perform 2D reconstruction. I'm trying to implement the algorithm to find center of rotation as ...
2
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0answers
73 views

How to subsample shift with sinc interpolation?

Does anybody know of a way to shift data by a fraction of a sample by using sinc interpolation? For example, shift an image to the right by 0.1 pixels. I'm struggling to find a formula or reference ...
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0answers
73 views

Method for determining Farrow coefficients

I've been reading the paper Polynomial-based interpolation filters for DSP Applications and I'm confused about how the coefficients for the farrow structure should be determined. My first approach ...
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1answer
153 views

Difference between subsampling and downscaling (image)?

I know that there are many ways to upscale (interpolate) an image using bilinear, bicubic, sinc... Somehow, these same algorithms can also be used to downscale an image. But when it comes to ...
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1answer
134 views

What is the difference between Linear Interpolation factor and Sampling rate conversion factor?

I have come across sampling rate conversion factor, which is given by: S_factor = F_new/F_old If F_new > F_old, then s_factor > 1 ...
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2answers
70 views

Can someone please explain or describe me the behaviour of equation 2 in my question, relevant to filter response (Sinc Interpolation)

At present, I am learning the theory of operation of resampling for bandlimited periodic discrete signals using sinc interpolation.I am developing a design flow and having difficulty in understanding ...
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1answer
42 views

How to determine best fit from two?

I'm studying some variances ($\sigma^2$), that in my case, they must depend by velocity squared $v^2$. So, in my experimental proofs, I have plotted a graph of $\sigma^2/v^2$, and I was hoping to ...
2
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1answer
123 views

Low order sinc interpolation vs. polynomial interpolation for variable fractional delay

I'm implementing a variable fractional delay element for use in online audio processing. Applications include ie. Karplus-Strong synthesis, flanger, chorus, echo, vibrato. I'm not oversampling, so ...
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1answer
944 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 ...
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1answer
67 views

Derivative of signal with missing samples

I have software that tracks an object moving (in the x-dimension only) across a video shot from a stationary camera. I need to find the velocity and acceleration of the object as functions of time. ...
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0answers
801 views

Image super resolution algorithm in Matlab

I'm trying to implement a simple Image super resolution algorithm (DWT-Based Resolution Enhancement ) in the following paper http://www.ripublication.com/aeee/52_pp%20%20%20405-412.pdf I tried to ...
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1answer
25 views

Modeling multipath distortion and shifting by fractions of a sample

I am working on modelling some FM transmitted signals, and I'm trying to figure out how to model the effects of multipath channels. The most obvious method is to delay the signal by some integral ...
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0answers
117 views

MATLAB implementation Spline Fitting

Let $s(t)$ be a signal that can be approximated by a uniform spline function of order $K$ (say $K=2$): $$s(t)\approx\sum_{n\in \mathbb{Z}}c_n\beta_+^{(K)}(t-n) $$ Suppose that we know the ...
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1answer
500 views

PSNR of two images of different size in matlab

I performed bicubic interpolation on a 256*256 image(img) dest = interp2(img,'bicubic') and i got a 511 * 511 image.I want to compute PSNR of a 512 * 512 ...
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1answer
193 views

Bicubic Interpolation

I'm trying to do bicubic interpolation on an 8*8 matrix(image) shown below. ...
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2answers
109 views

upsampling by huge factor

Assume i have a discrete signal, which i want to up-sample by factor 100. Up-sampling using poly-phase algorithm sounds like a bad idea, in terms of cache low-efficiency due to low space-locality of ...