Signal Processing Stack Exchange
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Questions tagged [downsampling]

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

Downsampling is usually done to reduce the data rate or the size of the data. The downsampling factor (commonly denoted by M) is usually an integer or a rational fraction greater than unity. This factor multiplies the sampling time or, equivalently, divides the sampling rate. For example, if compact disc audio at 44,100 Hz is downsampled to 22,050 Hz before broadcasting over FM radio, the bit rate is reduced in half, from 1,411,200 bit/s to 705,600 bit/s, assuming that each sample retains its size of 16 bits. The audio was therefore downsampled by a factor of 2.

Source: Downsampling.

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Downsampling, Filtering and Averaging

I have a signal of bandwidth DC to ,say, 100 Hz. I am interested in the range DC-10 Hz. I oversample by a factor of, say, 30. Thus the sampling rate is 600 samples/sec. Then I bandpass filter and decimate it over a number of stages, say 3 stages…
student1
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Level Correction For Digital Down-Convertion?

I am trying to understand a subtle (sorry if this is obvious) difference in the computed output power after a DDC process. Here is the story: Suppose I generated a 10 MHz signal from a microwave source at -10 dBm and feed it to the a digitizer. This…
Sandbo
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Trying to down-sample audio

I am trying to downsample from $44100Hz$ to $8000Hz$, and I am not sure what I am doing wrong here. $44100 / 8000$ is $5.5125$, so I am getting hung up a little on the fractional remainder which is causing my implementation to play back slightly…
patrick
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What if the Down sampling factor is not an integer?

I have developed a function which down samples an input signal.Say I have an input signal with a sampling rate of 512 samples/sec and would like to down sample it 128 samples/sec, then the down sampling factor is discrete and it is 4. In this case,…
PsychedGuy
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Most efficient way to downsample a signal by a factor of 2.5x

I know that to downsample by a factor of 2.5x one can upsample a signal by a factor of 2 and downsample by a factor of 5. I am wondering what is the best and more efficient way of downsampling by a factor of 2.5x?
TJ1
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Can Carrier Offset cause Image Problems

The main reason why we use the Direct conversion receiver with zero IF is that we don't have to deal with the problem of images. For achieving zero IF we need to ensure that the receiver Local Oscillator (LO) is working at the same frequency as the…
sarthak
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Why does downsampling increase the phase angle of poles in autoregressive models?

When reading about autoregressive models (AR), people often "downsample to increase the phase angle of the poles of the corresponding transfer function". How exactly does downsampling affect the phase angle of the poles?
paterpeng
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Observed Maximum Frequency Not Expected For Given Sample Rate

I'm downsampling a given .wav from 44100 to 22050 samples/second. When I play it back I'm looking at the signal with an EQ, and I would expect that I wouldn't see any content above ~11k. However, I see lots of high frequency content all the way up…
Valevalorin
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Duration of downsampled signal in analog frequency axis

Suppose, I sampled a signal, $x(t)$ and let $x[n]$ be the sampled signal of $x(t)$. Let then I downsampled $x[n]$ by a factor of $M=3$. Let $x[n]$ after being downsampled by the factor of $M=3$ yields $y[n]$. Now, my question is: if I plot the…
Md. Samiul Abid
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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 number, and another result being a combination of…
Tobi Akinyemi
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How should I downsample my sensor?

I have 2 sensors, sensor A is sampling a signal at 1kHz, and sensor B is sampling the a signal at 100Hz. Every timestamp that sensor B takes a measurement at is contained in sensor A. That is, sensor B takes a measurement essentially every 10th…
Dabbinator420
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Causal downsampling of a small buffer of GPS positions

Not sure this is the right place to ask, but I hope so. Context A GPS receptor is installed in a moving vehicle, and saves the measured positions with a resolution of at most $r_0$ to a small (a few dozen positions) buffer. The buffer is small due…
Rafael Almeida
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Downsampling an Oversampled packet

I have series of amplitudes of a signal recieved at center frequency of 433.9MHz, sampling at 250000 Hz. I can see the information received is the packet I am after, just sampled too high. I believe the transmitter transmits at 3918bps. What is the…
craig1231
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ADC way faster than microcontroller

I am getting into signal processing, and am working on a project. My analog-to-digital converter has a sample rate of 10 kHz, whereas my microcontroller can only handle up to 3 kHz. What does that mean? Will my Microcontroller get overspammed and…
user2276094
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