# Questions tagged [multirate]

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### Resampling n timeseries datasets with different sampling frequencies

I am currently working on an IoT project that uses datasets from different sensors with differing sample rates fs = (1s, 30s,...). I combine this with API data <...
1 vote
82 views

### Multirate systems - downsampling

As my teacher explained the process in class, I wanted to write a MATLAB code for learning purposes that downsamples a signal with a downsampling factor of L. Here's the code I wrote and the output ...
• 103
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### What's the advantage of the multirate filter banks?

Slower clocks mean lower power consumption, any other benefits? Could the multirate filter be more sharper than the single-rate filter? Previously, someone asked the similar question, but the answer ...
1 vote
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### Why is it said to be alias free in such a multirate system?

Page 246 in multirate systems and filter banks by P. P. Vaidyanathanm. The sampling in the first stage should have brought the aliases already, why does the author claim that it is an aliaa-free ...
92 views

### Room Impulse Response Domain of Sparsity

I have been studying the problem of room impulse responses (RIRs) interpolation for a couple of months. I am trying to use compressed sensing to reconstruct (at best) the sound field in the room with ...
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### Sample rate change using Lagrange interpolator

I'm trying to understand how to make Sample rate change by a non integer factor say $K=1.0012$ In real hardware I will be using cubic polynomial but for now I have chosen a linear interpolator. I have ...
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### Is the following system LTI and what is its purpose?

Above is a block diagram of a discrete-time system $T\{x[n]\} = y[n]$. Here, $h[n]$ is the impulse response of an arbitrary LTI system. Firstly, is this overall system LTI? I don't think so because ...
• 1,593
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### Cascade of Downsample and Upsample

Consider a cascade involving a downsampler (factor $M$) and an upsampler (factor $L$). For the sequence $$x[n] \rightarrow D \xrightarrow{{v_{1}[n]}} U \rightarrow y[n]$$ where $D$ denotes ...
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1 vote
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### Multirate Control System Transfer Functions

I'm interested in oversampling the inputs to a digital controller to increase the SNR of the input process variable signal. I've read on this site and in articles like the one below that it is not ...
• 296
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### Efficient CIC Decimation Filter in C

Does anyone have advice on efficient CIC Decimation filter implementation. I designed a basic 4th order CIC filter with a 64 decimation ratio in C (below). I am currently testing this on a Sharc SC589 ...
1 vote
343 views

### Z Transform of M-Fold Decimation

I know this is probably a common question, but after some searching I think that my version of the question is slightly different -- apologies if this is a repeat. I have seen that it is inaccurate to ...
• 11
326 views

### Decimation: how to preserve frequency content that lie above half the decimated sampling frequency?

I know that with three steps: complex demodulation lowpass filtering decimation we are able to select frequency contents in a band with reduced sampling rate. But this method only allows frequency ...
• 379
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### Getting error while performing upsampling of an audio signal processing using low pass filter in python

I want to perform upsampling of an audio signal introducing zeros between samples to create a longer signal with factor of N=2. The sampling rate is 44100Hz, time = 5sec. ...
104 views

### Hardware implementation of multi rate FIR filter

I have designed a multi rate fir filter in MATLAB and I want to implement it in verilog.This is the block diagram. Total number of taps are 391. Is there any way to automatically generate verilog ...
1 vote
201 views

### Direct and Transpose Polyphase Multirate Processing

Polyphase implementations of upsampling/ interpolation and downsampling/ decimation, after having invoked the Noble identities, are presented as follows (taken from Proakis): (Three-Channel Polyphase ...
• 11
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### Aliasing Issues in Sub Band Coding

The general structure of Sub-Band Coding (SBC) is shown below: The diagram shows that after each of the analysis filters, decimation is performed by a factor M which corresponds to the number of ...
• 488
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### Perfect reconstruction in two-channel filter bank

[from Discrete-time Signal Processing by Oppenheim and Schafer, 3rd ed.] I was not able to prove this: If the analysis and synthesis filters are ideal so that they exactly split the band 0 ≤ |ω| ≤ π ...
• 335
1 vote
336 views

### Downsampling after a highpass filter

Question: The following sentence is not clear to me (especially why down-shift occurs). Could someone explain it please? On the other hand, downsampling the output of the highpass filter down-shifts ...
• 335
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### Interpolated FIR filter (from Oppenheim and Schafer's Discrete-Time Signal Processing, 3rd ed)

[from Discrete-time Signal Processing by Oppenheim and Schafer, 3rd ed., p.196] Two questions: In this context, the filter with system function represented by Eq. (103) is called an interpolated FIR ...
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1 vote
178 views

### Group Delay of Mulitrate system

how do I find the group delay of multirate system.(sample rate converter) , IIR non-linear phase filter Say decimation by 2 (with lpf) = tf1(num,den) then again decimation by 2 (with lpf) = tf2(num,...
• 105
464 views

### What are the 'phases' in this 2D scaler filter

I am pretty new to DSP and have been looking at how image scaling is done in hardware. I and came across a 2D scaler core for an FPGA here. I have read up a bit about polyphase filters, but am ...
• 3
1 vote
192 views

### Where is the mother wavelet defined in the Fast Wavelet Transform?

Referring to the Fast Wavelet Transform, this transform is implemented as a QMF filter bank. This algorithm consists of high/low pass filtering and subsampling. However, a wavelet transform is ...
• 902
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### What is the multiplication rate in FIR filter

Consider a system implementing a rational sampling rate change by 5/7: for this, we cascade upsampler by 5, a lowpass filter with cutoff frequency pi/7 and a downsampler by 7. The lowpass filter is a ...
870 views

### Decimation FFT Result

In my Signal Processing class we just learned decimation however after messing around in Matlab trying an example of decimation, I just can't understand what's happening. I get the introducing twi ...
369 views

1 vote
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### Converting the equalizer coefficients from VSA at 2 sample/Symbol to 1.5 sample/Symbol

I was looking for some feedback on conversion of equalizer/filter coefficients at different sampler rate. Problem Statement: We have built a transmitter system whose output is at 1.5 sample/symbol (...
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121 views

### What does it mean for a Wavelet transform to commute with translations?

Referencing this article here https://arxiv.org/pdf/1203.1513.pdf It states "A wavelet transform commutes with translations, and is therefore not translation invariant". Now I understand why it is a ...
• 902
124 views

### Understanding sampling rate conversion

I am a little bit confused about the concept of sampling rate conversion. Consider the following question: Wideband telephony signals are sampled at a sampling frequency fS1 = 16kHz. To process these ...
• 467
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### 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' ...
• 467
1 vote
851 views

### Reversing the order of up and downsampling

When we are dealing with the problem of changing the sampling rate by a noninteger factor like L/M, we first need to the do the upsampling, and then the downsampling. My question is that under which ...
• 467
1 vote
410 views

### How should I modify my filter coefficients for the filter to be unaltered, when I change my sample rate

I am guessing this is a commonly encountered problem, but I am lost on how to really solve it. I have FIR filter coefficients that are used to match the frequency response of data sampled at 3 kHz. I ...
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1 vote
1k 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 ...
• 161
1 vote
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### Decimator effect on wide sense stationary input

I've seen that the output of a decimator when a WSS process is passed through remains WSS. I am not able to immediately see why this is. What is a good explanation of why the signal maintains ...
• 11
2k views

### What would be the effect of repeating samples in time domain on frequency domain?

Consider the operation of up-sampling a signal n times by repeating each sample n times in the time domain. What would the frequency domain response of the resultant signal be like given the frequency ...
1k views

### Unscented Kalman Filter - Multiple Consecutive Measurement Updates

In trying to implement an Unscented Kalman Filter (UKF), I have come across the issue of what to do when my measurement signals come in at a different rate than my control inputs, which I use in the ...
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157 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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### Sampling multiple sensors at different rates

I have a question regarding how best to sample data from multiple sensors when they are all updating at different/changing rates. I am new to data acquisition so please bear with me. For my Master's ...
249 views

### Multirate Signal processing for matching DAC of the SDR

I have been breaking my head for a long time. Please help with this..any input would be helpful! I am trying to implement a OFDM system using SDR (USRPN210 for Transmitter and USRP2 for receiver) ...