# Questions tagged [downsampling]

In signal processing, downsampling (or "subsampling") is the process of reducing the sampling rate of a signal.

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### Confused about filter's cutoff frequency in rational sampling rate converter

A interpolator which increase sampling rate by L times is followed by an anti-imaging filter, the filter is said to have a cutoff frequency of Fs/2L. Is Fs here is the frequency before or after ...
30 views

### How mic setting will affect audio classification model?

I have audio samples with three classes : 100 audio samples : class 'A' 100 audio samples : class 'B' 100 audio samples : class 'C' ...
50 views

### number of multiplications per second required by the system

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 π/7 and a downsampler by 7. The lowpass filter is a ...
30 views

### Can you downsample unevenly with even distribution?

Could I downsample a series of length 10 to length 7, with even distribution? i.e. Numbers get split across two (neighbouring) resultant numbers, as opposed to one result being a combination of 1 ...
83 views

### the number of multiplications per second required by the system

Q1. 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 π/7 and a downsampler by 7. The lowpass filter is ...
310 views

### How to determine the original size of the FFT used in unknown OFDM symbol

Given an unknown OFDM symbol consisting of 9144 samples, interested to know the size of the FFT used in the TX/Number of bins. Down-sampling to 512,256,128,64,32 yields the following. Do not see how ...
39 views

### The impact on the frequency of adding zero samples and non zero samples

Can someone give me a brief explanation of what is going on in here? I struggle to understand the full differences between the impact on the frequency of added zero samples and adding samples which ...
22 views

### Adding zeroes in between the samples of a discrete frequency domain leads to both zero padding and scaling

I won’t show ALL the calculations, but I’ll describe the problem fairly enough to understand. We’ve been taught that upsampling on one domain leads to padding zeroes or added time period which is zero ...
56 views

### How to sketch this multirate system spectrum?

In the following system: The signal x(n) is upsampled by 2 and then filtered. The signal and the filter have the following spectrum: After upsampling the spectrum of X would look the same except ...
743 views

### Downsampling from 100Hz to 60 Hz

I have two sensors measuring a single time varying signal . The first sensor (reference sensor) is sampling the data at 60 Hz and the second sensor (test sensor) is sampling the data at 60 Hz. I ...
39 views

### How do wavelet levels depend on one another?

I am working with wavelets for my thesis, and I would like to know if there is an intuitive dependency between the levels of a DWT. To make it clear: The DWT performs a convolution, and then the ...
164 views

### Downsampling and low pass filtering in one step?

Image pyramids are created by applying a lowpass filter (Gaussian) and then decimating the image (keeping only every n'th sample). In The Pyramid as a Structure for Efficient Computation the start ...
104 views

### How do I generate a smaller DFT result?

I have a very large input that I'm Fourier-transforming. Currently, I transform the entire signal and then downsample the result. Although the transform of the large input is expensive, my results ...
19 views

### Bandpass filter is not working as expected

The sampling rate that I have currently is at 384kHz and I want to downsample it down to 44.1kHz. I want to use a bandpass from 5kHz to 200kHz but I am only able to bandpass up to 192kHz for some ...
34 views

### Can largest-triangle-three-buckets downsampling method used with fourier transformed signal?

I've been reading on the largest-triangle-three-buckets downsampling method for downsampling. Though it was originally published in the thesis "Downsampling Time Series for Visual Representation&...
2k views

### Downsampling: Mathematical derivation

The problem I am having is related to sample rate conversion and more precise to sample rate reduction. I have been working on the paper Interpolation and Decimation of Digital Signals Tutorial Review ...