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5 votes

Is downsampling LTI for bandlimited inputs?

Is downsampling LTI for bandlimited inputs? No. Its linear but it's definitely does NOT meet the formal criterion for time invariance. Assuming $y[n] = T\{x[n]\}$ time invariance means $$ T\{x[n-k]\} ...
Hilmar's user avatar
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3 votes
Accepted

How does downsampling decrease the noise power?

White gaussian noise has constant power spectral density to frequency, in downsampling by 2 you are removing half of the available frequency band. Integration of power spectral density thereafter ...
DamienBradley's user avatar
2 votes

Downsampling of signal

I have two signals, for example, $x_1[n]$ and $x_2[n]$, which are the same for every $n$ except for $n_0$ and $n_1$. They are both bounded within a frequency range of $\pi/3$. That's a contradiction ...
Hilmar's user avatar
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2 votes

Benefit of Anti-Aliasing for Wideband Finite Time Duration Signals prior to Sampling

I am going to appear to contradict something that Dan Boschen said* in his answer. I'm not really contradicting -- just putting a markedly different spin on it than he did. You should use anti-...
TimWescott's user avatar
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2 votes

Benefit of Anti-Aliasing for Wideband Finite Time Duration Signals prior to Sampling

Yes anti-alias filtering is always necessary unless you are convinced there is no spectral energy in the frequencies that would otherwise alias in to the primary spectrum used including and ...
Dan Boschen's user avatar
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2 votes
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Lowpass filter to downsample data

Does it make sense? Is this a good way to downsample the data given the constraints that I have given? I don't think so, but from the words (without code or math) it's hard to to understand the exact ...
Hilmar's user avatar
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1 vote
Accepted

call decimate function from matlab

Matlab uses double values by default. Scipy.signal.decimate expects an integer as the second argument, the decimation factor. ...
Jdip's user avatar
  • 6,265
1 vote

What is the best method of describing the effects of downsampling on a chromatographic signal?

There are several possible metrics that come to mind. The first step would be to upsample the downsampled signal to the original sampling rate. This would be unneccessary if you can get your hands on ...
Max's user avatar
  • 2,368
1 vote
Accepted

Does SDR configured with low sample rate automatically averages samples?

If the SDR and ADC is designed to sample at 100 MHz, then the analog anti-alias filter of properly designed is also wide enough for most of that bandwidth up to Nyquist (or could use bandpass sampling ...
Dan Boschen's user avatar
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1 vote
Accepted

Is downsampling LTI for bandlimited inputs?

Directly, no - but in an important way, yes: downsampling is LTI within recovery, or "rLTI" for short. Downsampling is always linear - "summed inputs $\Leftrightarrow$ summed outputs&...
OverLordGoldDragon's user avatar
1 vote
Accepted

Can we do down sampling by taking fft, omitting samples on the ends of the spectrum, and then taking inverse fft?

Suppose that the the maximum frequency content of the signal is low enough that we do not have any concern about aliasing. ... Can we take the FFT of signal, then omit samples from 1023-th index up to ...
OverLordGoldDragon's user avatar
1 vote

Image downscaling methods

Image scaling is a variation on the dsp topic of resampling. A text book on resampling to a lower rate tells us that a lowpass filter that remove all signal energy beyond 1/2 the sampling rate of the ...
Knut Inge's user avatar
  • 3,434

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