# Questions tagged [multirate]

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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 ...
176 views

### 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 ...
247 views

### 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 ...
1 vote
194 views

### 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 ...
539 views

### 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
218 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 ...
212 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 ...
289 views

### 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. ...
101 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
163 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 ...
77 views

### 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 ...
134 views

### 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 ...
1 vote
282 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 ...
159 views

### 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 ...
1 vote
134 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,...
382 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 ...
1 vote
163 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 ...
215 views

### 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 ...
651 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 ...
320 views