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Questions tagged [nyquist]

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Applying Nyquist theorem to digital vs. analog audio quality

I had a recent conversation with a friend about analog vs. digital recordings. He shared his opinion that music recorded by analog techniques is of superior sound quality to music recorded by digital ...
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2answers
137 views

Aliasing in audio

Reading wikipedia to be sure and it says: In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable (or aliases of one another) ...
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1answer
104 views

Stable gain nyquist plot

From Modern Control Engineering 5th Edition page 469 The transfer function of a plant controller by a proportional controller is given by $$G(s) = \frac{K(s+0.5)}{s^3 + s^2 + 1}$$ In the book $G(j\...
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1answer
169 views

Under what conditions do the phase margin and Nyquist criteria give the same results?

When designing feedback systems, I often evaluate stability by thinking about phase margin: the closed loop system $$T(s) = \frac{L(s)}{1+L(s)}$$ is stable if $L(s)$ has positive phase margin, i.e., $...
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Is there is any other filter combination I can used to produce the better output characteristics as SRRC?

http://www.wirelessinnovation.org/assets/Proceedings/2005/2005-sdr05-2-2-03-harris.pdf I am building better pulse shaping filter to reduce in-band ripple and out of band attenuation. I have been ...
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1answer
216 views

Fractional Delay Filters and Cutoff Frequences

I am trying to implement an interpolator for arbitrary sampling rate conversion of a one-dimensional signal (a fractional delay filter). I am aware of the fact that interpolation is in general a ...
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1answer
1k views

Link between DFS, DFT, DTFT

My understanding of DFT is as follows For a signal $x[n]$ of finite-length, the DFT is DFS of the periodic extension, $\tilde{x}[n]$, of that signal $x[n]$ and also another way to view DFT is that it’...
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103 views

Discrete Time Processing of Continuous Time Signals LTI Concept

I wonder if the input signal (CT) violates Shannon-Nyquist Theorem for a given sampling rate, is there any chance for the overall system not to be LTI although discrete time system is LTI? Thanks.
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Root raised cosine pulse shaping filter

What are disadvantages of root raised cosine pulse shaping filter in digital communications and why does it need to be improved? Links: Square Root Raised Cosine Fractionally Delaying Nyquist ...
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1answer
43 views

Power Line interference with different Sampling frequency

I've been playing around with EEG data from an online database. If the power line interference (PLI) is at 50Hz and sampling frequency is 64Hz, then according to the Nyquist theorem, the 50Hz PLI ...
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6answers
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If humans can only hear up to 20 kHz frequency sound, why is music audio sampled at 44.1 kHz?

I read in some places that music is mostly sampled at 44.1 kHz whereas we can only hear up to 20 kHz. Why is it?
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1answer
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Estimating the Nyquist rate when simulating data

I want to find the power spectrum $\tilde{Q}(\omega)$ of a quantity $Q(t)$. The values of $Q$ are computed at discrete time steps so I have a series $Q(\Delta t)$, $Q(2 \Delta t)$, ... of values, but ...
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2answers
208 views

Changing the Bandwidth of a signal of fixed Sampling frequency [closed]

If sampling frequency is fixed, how can I generate a frequency domain signal of a particular bandwidth from a time domain signal of dimension $1\times N$? e.g. if $f_s=100\,\text{kHz}$, how can I ...
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1answer
187 views

Reconstruct under sampled signal

I have a signal from a PWM inverter that was sampled at 3,84 kHz. The PWM has a switching frequency of 5 kHz. The pwm signal is feeding an induction motor. If I low-pass filter the PWM signal it ...
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1answer
206 views

what is difference between Alias vs. down sampling? [closed]

could someone help me explain downsampling in the context of Nyquist–Shannon sampling theorem and tell the difference between Aliasing and downsampling.Also is downsampling and undersampling the same ?...
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2answers
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Bandwidth with complex sampling

On the transmit side, I have a 20 MHz carrier frequency carrying a signal with bandwidth of 40 MHz (so 0 Hz to 40 MHz, center at 20 MHz). On the receive side, I have a dual channel ADC with each ...
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1answer
3k views

Nyquist criterion for zero isi

I am working with the Nyquist criterion for zero ISI when I find something that makes me think that I misunderstood this criterion. What Nyquist says is that to avoid ISI in the sampling we must ...
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3answers
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Nyquist plot interpretation when curve hits the origin

I'm a bit confused about the interpretation of the Nyquist plot when the origin is part of the plot. In this case I'm not even considering closed loops, I'm just looking at the Nyquist Plot of a given ...
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2answers
409 views

Nyquist frequency and DC

Im studying the DSP book by Steven W. Smith. On page 41 he covers the Nyquist frequency. He makes up an example by writing the following. ... consider an analog signal composed of frequencies ...
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2answers
533 views

Nyquist frequency - Sampling theory

If a signal contains frequencies from $500$ to $1000\textrm{ Hz}$, what is the Nyquist sampling frequency, $2$ times $500$ or $2$ times $1000$? Twice the highest frequency of the signal, or twice ...
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Determine maximum frequency of input signal to make system LTI

This is question 4.26 from the third edition of Alan Oppenheim's textbook "Discrete-time Signal Processing". It is stated as follows: Firstly, the answer is the input signal should be bandlimited to ...
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1answer
434 views

Digital signal and frequency analysis

I am generating a digital signal with software. I have defined the vector $$[0,1,1,1,0,1,0,1,0,1,0,0,0,0,0,0,0,0,0,0] $$ and my sampling rate is 8 million per second. The frequency spectrum is ...
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2answers
53 views

Minimum recording time for a signal

I am familiar with both Nyquist frequency and Nyquist rate. What I cannot seem to find information on is the minimum time necessary to detect a signal. In my use case I am using a multiplexer to ...
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3answers
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Signal values we will 'miss' between sampling instances during sampling of band limited signals

According to the Nyquist–Shannon sampling theorem, any continuous time signal with a bandwidth $B$ smaller than Nyquist frequency $f_N=f_s/2$ (with $f_s$ the sampling frequency), which is sampled at ...
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5answers
763 views

Confusion regarding Nyquist Sampling Theorem

The first time Nyquist Theorem was mentioned in class. It stated that we should sample at twice the highest frequency content of the signal. Example: If we wanted to sample $\cos(2 \pi f_0 t)$, the ...
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1answer
195 views

Nyquist rate determination and oversampling [duplicate]

I'm new to this. I'm using ShannonGui to generate a sine wave with a $1\textrm{ Hz}$ signal frequency. From what I can tell to determine the Nyquist rate I need to double the highest frequency, since ...
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1answer
629 views

Properties of root raised cosine filter

In communication systems, the transmitted signal is often passed through a root-raised cosine filter to avoid, in textbook language, intersymbol interference (ISI). An identical filter at the receiver ...
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1answer
476 views

Convolving a discrete time sequence with a continuous-time filter?

I am a newbie to DSP, and have what seems to me a fundamental question. I have a discrete-time sequence $g[n]$ of length $N$. I am supposed to pass this signal through a root-raised cosine filter $...
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3answers
354 views

Time Domain Example of Nyquist/Shannon?

I looked at an old thread, Nyquist Frequency Phase Shift, but was left wondering still about oversampling. I learned Shannon 40 years ago, then worked 30 years in (s/w) engineering, but now retired I ...
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1answer
531 views

Sampling theory and frequency spacing

If a CT signal $x(t)$ is sampled for one ($1$) second and $4096$ samples are generated: Isn't the highest frequency that can be sampled without aliasing ($4096/2$) $2048\textrm{ Hz}$? If a $4096$ ...
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1answer
352 views

Elegant way of calculating minimal sampling frequency without aliasing for annoying signals

Given a symmetric Fourier transform with finite support as below, there's an algorithmic procedure to determine the minimal frequency for sampling without aliasing: Find an integer $L>1$ ...
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1answer
198 views

Given a continuous time signal, does the minimum Nyquist sampling rate depend on the choice of the set of basis functions?

This is my first question on a StackExchange. When the basis functions to represent a signal are chosen as $e^{j\omega t}$ such as in a continuous-time Fourier transform then the sample rate $f_\...
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0answers
61 views

Confusion in Nyquist criterion

Does the Nyquist criterion limit only the maximum permissible frequency, according to $B$ should be less than $f_s/2$ where $B$ is the highest frequency of the signal? Or does it have any ...
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1answer
190 views

Determining the Nyquist rate of signals added and multiplied together

Suppose I have a signal in the frequency domain $x(\omega)$. Suppose I know that its Nyquist rate is $\omega_0$ (and let $\omega_m$ be the its maximum frequency). I need to get the Nyquist rate of $...
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1answer
117 views

What is the maximum allowed transition band of the low-pass filter used in the reconstruction kernel for a CD with maximum speech frequency of 4 kHz?

My question is if the transition band in the question below would be from 4Khz to the Nyquist frequency of 22.05Khz or from 4Khz until 44.1Khz-4Khz=40.1Khz?
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1answer
338 views

Output a sine wave from samples-limits?

Using a micro-processor of 48MHz, I am trying to output a sine wave from the DAC (digital to analog ), and I am not sure if my ...
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2answers
2k views

The relationship between downsampling and frequency resolution

I am having trouble understanding a concept that I have seen in many published papers. For example, in this paper (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0082748) they wrote ...
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1answer
3k views

Calculating a signals frequency when given the number of samples

This place has been great in helping me to understand my online image and signals class! I've moved on to another question and wanted to see if I'm correctly grasping the subject. The next question ...
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1answer
181 views

What is the LOW frequency resolution rule analogous to Nyquist?

If I'm analyzing a signal in the frequency domain, I know about the well known Nyquist criteria that the sample frequency must be > 2x of the highest component present in the signal. However, there ...
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1answer
36 views

Nyquist (Nth) digital filters

I am working in something were I should use a upsampling filter. I have decided to use a Nyquist filter(Lth filter). I know that there are two constraints. The first The frequency vector values must ...
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1answer
49 views

How is the 'max frequency' of a signal fixed?

It is well known that no time-limited signal is frequency-limited. So the frequencies of a time-limited signal extend upto infinity - may be decaying slowly or fastly in frequency domain. But we take ...
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4answers
264 views

Sampling Theorem: How to know the value between two samples of a Signal

According to Sampling theorem, in order to reconstruct a signal we need to sample it at the rate => twice the highest frequency component of that signal. (provided signal is band limited). Let's say, ...
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1answer
188 views

Noise Peaks Near Nyquist Frequency

I am working on an audio upsampling/oversampling project where I am testing different interpolating schemes in hardware and comparing measurements to my expected results. In one of my interpolating ...
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2answers
654 views

Sampling frequency lower than half of sampled signal frequency?

In GNURADIO when RTL-SDR Source block is placed there is a parameter Sample Rate (sps) and ...
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2answers
4k views

Why is a square wave aliased?

I understand an ideal analog square wave contains sine-wave-components above Nyquist frequency (and towards infinity) and is thus subject to aliasing. So obviously we need an anti-aliasing-filter. Or ...
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1answer
459 views

Relation between bandwidth and data rate

I have trouble understanding the following from wikipedia - Bandwidth (Signal Processing) A key characteristic of bandwidth is that any band of a given width can carry the same amount of ...
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1answer
151 views

Find minimum sampling rate of non-ideal notch filter

Old test problem: "You have been asked to design a real-time digital filtering system that eliminates a band of frequencies between 20 and 30 MHz but preserves everything else. The system uses an ...
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1answer
779 views

Choosing minimum sampling frequency of a filtered signal

I have a time series of acceleration sampled at 1000Hz to capture random impacts on a structure. The ringing of the structure (not of interest) produces noise which a 50Hz filter seems to eliminate ...
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1answer
79 views

Sample Frequency - Recommended Practical Nyquist, Lower Used by majorities appications

Doubt1: What is the Lowest Sampling Frequency used by majorities sound applications. Is there limited frequency sampling lower than 8KHz In C/C++? Comment In Java I haven't detected any problem, but ...
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2answers
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Difference between Nyquist rate and Nyquist frequency?

So I've been searched online and can't seem to find a clear cut answer to this question. From my understanding, the Nyquist rate is double of the maximum frequency of a signal which Nyquist frequency ...