Questions tagged [polyphase]

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Decimating Polyphase Filter in Simulink

I have read many of the articles on the website regarding a polyphase decimating filter structure. I'm sure we are all familiar with the typical image shown in Fred Harris Multirate book and many ...
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1answer
35 views

What is the difference of each frequency response of partial filters in a polyphase method

I try to understand how works polyphase method in term of frequency response of partial filters. Of course, the common is that the filters operate at low frequency, but what differency between them. ...
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3answers
70 views

Upsampling with time offsets

Suppose I have done 4x oversampling for a continuous time signal, but the successive sampling times have a linearly increasing offset. Specifically, the samples with indices {4k; k=0, 1, 2,...} are ...
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1answer
48 views

How to perform convolution using polyphase structure

I am trying to implement convolution using polyphase structure but, how to split input samples among different filter banks is my major doubt. Please explain the same with example?
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1answer
38 views

Coherent averaging of polyphase components of a signal

I want to subsample a multi-band signal to introduce controlled aliasing. My frequency components are uniformly distributed across the spectrum (comb structure) and occupy a relatively narrow ...
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3answers
177 views

The z factor in polyphase decomposition

I'm a beginner in DSP and I'm going through the textbook of Oppenheim's Discrete Time Signal Processing. There are two figures in the text, one which I can visualize, and the other I can't. The first ...
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0answers
128 views

Polyphase resampling delay

I want to implement polyphase resampling. For this, I wrote a script in matlab. The script performs the following sequence of actions: ...
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0answers
61 views

What is the threshold to prefer polyphase channelizer over FIR filtering?

A wideband signal need to be processed to extract several narrowband channels from it. There are two straightforward approaches to do so: For each narrowband channel shift frequency and filter it ...
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1answer
33 views

Polyphase components Spectrum formula in Discrete time

I am trying to understand the meaning behind some of the components of the formula for polyphase components in discrete time. Note that $\Omega$ indicates discrete in this notation and the formula is ...
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0answers
111 views

Why do I have to scale filter coefficients during bandlimited sample rate conversion?

I am writing an example for how to perform sample rate conversion using windowed sinc and polyphase filters. Here is the C++ code as a github gist. So far, this works, and I think I have understood ...
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0answers
67 views

Sampling rate conversion and polyphase decomposition

Can someone please explain the answer to this problem: The sampling rate of a baseband signal shall be converted from 5 kHz to 7.5 kHz using the efficient polyphase implementation with a 'rotating' ...
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1answer
241 views

Polyphase decimation filter plot in Octave

I'm using de Soras hiir library for decimation and I'm trying to verify the filter design in Octave. The filter is a polyphase 2x downsampling filter with 96dB attenuation and 0.01 transition band, ...
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0answers
84 views

Polyphase FIR image downscaling

I recently started designing a Polyphase FIR filter in with a lanczos kernel interpolator to resample an image in Python. The goal is to downscale the image using these methods. However, I think I don'...
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2answers
360 views

Polyphase Analysis Filter Bank

I have a question regarding the polyphase DFT filter bank implementation in this page. (https://cnx.org/contents/Peqc-TK2@16/Uniformally-Modulated-DFT-Filterbank) In figure 2, to analyze the kth ...
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0answers
144 views

Exploiting coefficients symmetry of a FIR interpolation filter in a polyphase implementation

I'm trying to figure out whether there is a way to exploit a symmetry of a FIR interpolation filter in a polyphase implementation. I know for a fact that we can exploit the symmetry in a normal FIR ...
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3answers
373 views

Fractional Delay using Polyphase Filter

How to use rectangular window design to design a length-9 polyphase filter which delays an input signal by 3/5 of a sample? An expression for the 9 coefficients is required.
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1answer
686 views

16x interpolation using polyphase FIR - sum of the coefficients

I have an issue with polyphase implementation during interpolation. Lets assume I have 256 taps long FIR lowpass sinc filter. In order to interpolate by a factor of 2 I do use two FIR filters (...
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1answer
85 views

How to undo dynamic Doppler effect by software?

I have a signal affected by Doppler effect. In general, the Doppler effect changes the scale of the time and frequency domains. So, to undo this phenomenon, I am using a sampling rate converter. Two ...
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1answer
814 views

Polyphase Filter decomposition. It is not working

So, I want to do a polyphase implementation of a filter bank (I had problems with it since the beginning and I already asked for help to the community in the past, indeed: Norm MPEG-1 Layer III (Mp3) ...
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3answers
2k views

How to implement Polyphase filter?

I am trying to implement the following 4-Tap Polyphase window shown in figure below and used in : polyphase filters- radio astronomy: lecture #8 by Prof. Dale E. Gary on Matlab. I have tried splitting ...
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0answers
57 views

How to initialize shift registers in polyphase filter based resamplers to avoid or compensate for group delay?

I have a signal a = [a(t0),a(t1),a(t2),..,a(tN-2),a(tN-1)] I'm using a polyphase filter based resampler with filter length $L$ of $8$, fixed interpolation rate $I$ of $10000$ and decimation rate of $...
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1answer
421 views

Understanding spectra in polyphase filter banks

I'm trying to fully understand the spectral effects in a polyphase channelizer / polyphase analysis filter bank. I don't really have a signal processing background, so please excuse some incorrect ...
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1answer
304 views

Relative Computational Complexity for Channelizer Implementations

Suppose I want to separate a broadband input signal into multiple narrow subbands using an FFT-based analysis filter bank. The filter bank uses a prototype lowpass filter and is implemented using a ...
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1answer
251 views

Zero Order Hold with polyphase resampler

I'm trying to design a FIR filter(direct form) the coefficient of which will be used to design a polyphase resampler that does Zero-Order Hold resampling. If the direct form impulse response is ...