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16 views

Specifications (N) FIR Low Pass Resamplig, Hamming Window

I'm learning about DSP and I've doubts. The resampling process can be do it with only one filter. $L$: Increment Sample Rate Integer $M$: Decrement Sample Rate Integer $f_S$: Frequency Sampling ...
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1answer
37 views

How to ensure anti-aliasing in image resampling at lower resolution?

Suppose I have a 1D image with intensities $f_i$, $i=[0,n-1]$, where $n$ is the number of pixels. I want to downsample it to have $\frac{n}{2}$ pixels (let $n$ be an even number). For each new point I ...
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2answers
193 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 ...
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1answer
34 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 ...
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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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4answers
98 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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2answers
137 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 ...
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1answer
210 views

Unexpected results for fourier resampling (Python 3)

I am trying to resample a signal using the fourier method in python using np.fft.rfft() and np.fft.irfft(). (I'm not using ...
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0answers
27 views

Unexpected peak after up & down sampling

I am working on signals to check how approximation can change the results. I am testing on example that can change frequency from 22kHz to 20 KHz. I prepare this script in MatLab ...
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1answer
65 views

Additional peak after resampling

I prepared a Matlab script, which re-samples spectrum from 24kHz to 20kHz. When I used up-sampling, a fir filter, and then up-sampling again at the end, I get an additional peak at 4kHz which is not ...
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0answers
40 views

Spatial resampling, how to smooth?

Sorry if this is not the right forum. Having a velocity grid in which a wave propagates, and given a certain spatial sampling of the grid, what kind of smoothing/interpolation should be used if the ...
0
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1answer
52 views

How to increase the resolution of a video from a sequence of photos?

I have a video filmed in a relatively low quality and resolution and a sequence of photos of higher quality taken of the same scene at the rate of about one image every two seconds or so. Could those ...
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0answers
57 views

Is there an exact solution for this re-sampling problem?

I want to know if there is an exact solution for the following problem and how to approach solving it: I have a discrete-time signal where the Nyquist theorem is satisfied: $r_k = \sum_i ...
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1answer
75 views

Integral of an upsampled signal, without actually resampling it

Given a signal X which is sampled at a certain frequency. The value we currently compute is given as the integral of the upsampled signal. Thus: Y = X but 100 times upsampled, by means of sinc ...
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0answers
36 views

Is Bernstein ever used in DSP?

In the early 1900s, Bernstein proved you could approximate any continuous function with the sums of polynomials. I know this is a bit weak for DSP because it isn't strictly periodic, but is Bernstein ...
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3answers
220 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 ...
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0answers
66 views

calculating FFT of signal with additional zeros

I have a problem where by I calculate the FFT of a signal $x$ (an image to be exact) after zero padding it: X=fft([x zeros(n)]) where $zeros(n)$ is just the ...
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2answers
108 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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1answer
94 views

Resample with unknown rate change

I am doing digital signal processing for a software defined radio. I have a signal coming in packets of data (several samples) at an average sample rate of approximately some known value FSin. I am ...
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2answers
404 views

Resample an array in real-time (application: pitch-bend)

I'm working on a sampler software (that plays .WAV files, when notes are played on a MIDI keyboard). In order to implement pitch-bend feature (i.e. you have a "pitch bend wheel" on the synth and you ...
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1answer
138 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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0answers
59 views

Most efficient phase linear x4 resampling algorithm

I'm working on a program in which I need to do the following about 20 times for each block of audio: - Upsample from 192 to 768 kHz (x4) - Clip - Downsample back to 192 kHz (/4) What I'm using now: ...
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1answer
231 views

Resampling signal in MATLAB

I read a wav file in MATLAB and it has a sampling rate of 16kHz. I want to pass it through a filter I designed which has a sampling rate of 44.1 kHz. So, I thought I would use ...
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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
957 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 ...
3
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2answers
577 views

OFDM transmitter bandwidth

Theory Suppose an OFDM transmitter with four subcarriers is implemented using the structure shown below. If the serial data input rate is 40 bps, each parallel stream will run at 10 bps. ...
0
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1answer
256 views

Algorithm implemented in the timeseries\resample function of Matlab

Does anyone know what algorithm is implemented in the Matlab function resample for timeseries? I had a look on the manual but it just gives the instruction to use ...
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0answers
794 views

How to compute transfer function (Frequency Response Function) from experimental data

I have a set of data, in the freqeuncy domain, corresponding to a structural test. I have amplitude, phase and frequency for both the measured output and the input signal (accelerations are measured ...
0
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1answer
53 views

What is a correct way to downsample an impulse train

So I have a signal which is caused by an impulse train. I can determine the impulse train with 500hz but sample my output signal with only 10hz. Then I want to calculate an impulse response function. ...
0
votes
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 ...
0
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1answer
130 views

frequency divider

How would one implement a frequency divider? I know I can resample up and then treat it as if I'm at the same frequency, however I want to divide the frequency of my signal by 2 and keep the same ...
0
votes
2answers
132 views

How to change the start point of resampling process?

I'm trying to resample a digital communication signal in SciPy or Matlab. Suppose the signal was sampled at 3 samples per second, and I want to resample it to 2 samples per second, the thing is I also ...
1
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1answer
573 views

Does audio upsampling create noise/artifacts or degrade the signal?

I've read that upsampling performed in digital music playback can color the sound, produce artifacts, etc. For example, an audio file ripped from a CD might be 44.1Khz/16-bit, and then upconverted to ...
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3answers
155 views

Integer upsampling - leave original samples unaltered

I'm looking at the problem of integer upsampling (i.e. interpolation). This can be achieved by first increasing the sample rate by factor $L$ (i.e. inserting $L-1$ zeros between the original samples) ...
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3answers
345 views

filter and resample or resample and smooth?

Currently doing some signal analysis in python for a major project in my physics degree which is due really soon. I need some help! Say I have two signals, f(t) and g(t) which are recorded over the ...
1
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1answer
981 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 ...
4
votes
1answer
149 views

Downsampling oversampled image (smallest size which retains image 'detail' within acceptable limits)

I have a large collection of oversampled images (family photos of varying 'sharpness' scanned at a uniformly high dpi) and would like to downsample them to optimise storage space whilst retaining ...
0
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2answers
419 views

Doing resampling, how can we choose lower cutoff frequency for LPF filter?

I would like to resample an audio signal. Sampling frequency of an original audio signal is 50k Hz. What I want to down sampling frequency is 30k Hz. In this case, I followed the procedures as ...
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3answers
1k views

Why is biquadratic interpolation for image resampling rarely done?

Related question: What are the practically relevant differences between various image resampling methods? Bilinear and bicubic interpolation for image resampling seem to be fairly common, but ...
1
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0answers
104 views

Upsampling very large data sets efficiently

I have gigabytes worth of seismic ground data, that I wish to upsample by a factor of 2 or 3. I wanted to ask what efficient way might there be for me to upsample such a big file? Is there a way to ...
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2answers
2k views

Is interpolation (interp1) better than FIR filtering when rational integers are close to 1?

Question I've been attempting to resample a GPS signal in MATLAB. I've built a few FIR filters using fvatool and from handmade transfer functions (punched out with ...
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2answers
2k views

Downsampling - upsampling FFTW

I'm having 2 signals which have different sampling rates i.e., 1ms(A) and 4ms(B) and I've tried to upsample/downsample either of the signals based on the code snippet Resampling based on FFT which I ...
5
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1answer
183 views

Detecting the original bandwidth of upsampled recordings

I have a set of recordings sampled at 16khz, but some of them are upsampled from 11khz and some from 8khz. Quite some of the recordings are noisy. What is the best way to classify the recordings ...
2
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1answer
392 views

How do I convert a filter from Spatial to Fourier domain?

I have a small 2D Gaussian image filter that I am currently applying as a window by convolution. I would like to do this in the Fourier domain as a single multiplication. I would like to convert my ...
3
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1answer
202 views

Explanation of LidarBoost Algorithm?

I am trying to understand the LidarBoost algorithm as explained in this paper (PDF warning). I don't understand how they take the original depth-images $Y_k$ and transform them into the up-sampled ...
17
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6answers
7k 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 ...
3
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1answer
368 views

pitch vs playback rate

Let's say I have an audio sample, whose pitch is known to be C4 (don't wanna go in detail here, let's say I just sampled a tuned piano playing the C4 key). The rules of the game are: I can only ...
8
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1answer
152 views

Rotating a 3D image

I've got a 3D image of non-isotropic voxels, to which I'm applying a general rotation. How could I go about determining an appropriate voxel size for the rotated image? I need to minimize loss of ...
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4answers
4k views

How can I resample a signal with an arbitrary factor (e.g. 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 ...
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3answers
5k 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 ...