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1answer
32 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 ...
0
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1answer
19 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
42 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
55 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 ...
1
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1answer
75 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 ...
3
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1answer
68 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 ...
0
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1answer
14 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 ...
-1
votes
1answer
26 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 ...
2
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4answers
172 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, ...
0
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1answer
84 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 ...
-1
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2answers
71 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 ...
1
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2answers
226 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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0answers
23 views

What is the cut off frequency when design pre-filter for downscale image to avoid moire effect?

Let's say I want to downscale an image, to avoid moire pattern, I need to design an low pass filter to blur the image before decimate. The question is: What's the cut off frequency should I set as ...
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1answer
42 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 ...
1
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1answer
27 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 ...
0
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1answer
34 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 ...
1
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1answer
21 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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0answers
39 views

Finding the Nyquist Frequency of Irregularly Sampled Discrete Data

According to L. Eyer et al. (1999), the correct Nyquist frequency of irregularly sampled data is $$ \frac{1}{2p} $$ Where $p$ is the largest value such that: $$ \forall t_i,t_i = t_1 + n_ip \\ ...
3
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1answer
79 views

Benefits of oversampling in a realtime noise-cancellation system

When sampling a signal, it is standard practice to use a sampling rate that is greater than two times the bandwidth of the signal in order to avoid aliasing. The result is then low-pass filtered (and ...
0
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1answer
48 views

Why doesn't the sampling theorem work in this case?

In this example, under "Discussion", we can see that the Nyquist sample rate will result in samples with the value zero only. But why is this? I thought the sampling theorem said that if you sample ...
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2answers
68 views

Nyquist Frquency isn't what it is supposed to be

I am new here and also am not very knowledgeable about DSP so this might be dumb and easy. I am aware of the fact that in order to reconstruct a signal, I need to sample it at a frequency that is more ...
-1
votes
1answer
41 views

Nyquist Rate Determination

If the Nyquist rate for xa (t) is Ωs, what is the Nyquist rate for xa(2t)? Will it be the same, increase 2 folds or decrease 2 folds?
0
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1answer
56 views

What does it mean for a signal to alias to another?

I know the definition of this is simple and I do understand the concept of aliasing (I think) in the way that multiple signals can be aliases of each other. For example, I get it when some one says: ...
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0answers
62 views

I still get aliasing of my signal, even though I stay below the Nyquist frequency. What am I missing?

Thanks in advance for any help with my newbie question. I've been consulting quite a large number of resources in order to understand how I can create and playback a nice sawtooth without aliasing, ...
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0answers
99 views

Sampling rate: camera resolution when taking a photo of an LCD

Consider a digital camera that faces an LCD and that is perfectly focused on the LCD. The LCD shows an image of $n \times n$ pixels. What resolution does the camera have to have to perfectly capture ...
0
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0answers
33 views

Do we have aliasing with this chip rate and transmission bandwidth

A particular communication system I came across defines chip time to be 0.57 ns and consequently chip rate is 1760 MHz. The transmission bandwidth is 2.16 GHz. I am wondering, do we suspect to have ...
0
votes
1answer
125 views

Downsampling and Gaussian filtering in the context of scale space pyramids

In the context of scale space image pyramids using Gaussian filters I noticed that it's common to downsample the image after blurring with $\sigma = 2*\sigma_{init}$ . My question is: What is the ...
0
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1answer
27 views

Compressed Sensing vs Common Compression Approaches

I have a very basic question regarding common compressing approaches. Often, I have heard something like "The problem in our common way to compress data is, that we have to acquire a huge number of ...
0
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1answer
25 views

Cannot recreate a simple Nyquist series in Matlab

a Nyquist series should look something like {...-1, 1, -1, 1, ... }, which i think means it is a sine wave sampled at the peaks and valleys exactly. Now, given a sampling rate of 48 Hz, the Nyquist ...
0
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1answer
32 views

nyquist fequency

simple question, but I cant seem to understand how they got the answer. I have $x(t)$ as a signal, and I'm told that its Nyquist frequency is $\omega_0$ I'm asked - what is the Nyquist frequency of ...
0
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1answer
28 views

input output read/write frequency

I am trying to identify a system based on input/output response and thereby estimate a transfer function. I generated a frequency sweep function in Mathematica which gives me the discrete values of a ...
0
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2answers
91 views

ISI Nyquist criterion and spectral efficiency

While reading Bernard Sklar's Digital Communications book I've got confused with ISI Nyquist criterion (not Nyquist rate criterion). There is stated (Sklar, 3.3 section) for symbol rate $R_s$ minimum ...
0
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1answer
51 views

100 kHz sinewave contaminating a signal sampled at 48 kHz

If sampling at a rate of 48 kHz, with no anti-aliasing filter on the input, and the input signal is contaminated by a 100 kHz sine, at what frequency would the sinewave signal appear in the output ...
1
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1answer
135 views

Why remove energy at Nyquist before ifft?

I've heard that you should remove the energy at Nyquist before performing the ifft. Why is it that you can't leave the Nyquist energy there, is there danger of aliasing somehow?
0
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1answer
22 views

Sending a Filtered vs Non-Filtered speech over a Communication Link

To send a $10 \, KHz$ bandwidth of speech (Non Filtered speech), Nyquist criteria says that sampling duration should be $50 \, \mu s$. While for a $4 \, KHz$ bandwidth of filtered speech, sampling ...
1
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1answer
57 views

Nyquist Criterion in higher dimensions

I was just wondering if there were any "obvious" resources, papers, or textbooks I should look into regarding the nyquist-criterion in higher dimensions. For example, this would be relevant if there ...
1
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1answer
132 views

What is the minimum sampling duration to capture a given frequency?

Due to the Nyquist rate, you need to sample twice as fast as the highest frequency you want to measure. Then when you do a FFT the number of samples determines the number of bins and thus the ...
1
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1answer
61 views

Processing 47-53 MHz signal sampled at 96000 Hz

I am fairly new to the topic of DSP and FFT and I have hit a mental block. For a project, I am trying to pick out frequency's with amplitude peaks in a 47-53 MHz signal. This signal is being put ...
2
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2answers
149 views

What is the proof of the equation for the aliased frequency fa = |R*n - fs|?

R (sampling rate) fs (signal being sampled fN (the Nyquist frequency) fa (aliased frequency) I was hoping someone could explain to me why this is true with a more mathematical proof. it seems ...
2
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3answers
112 views

Soft question: Why do we need to reconstruct a signal?

I am currently reviewing the Nyquist criterion which says I need to sample the signal at 2 times the maximum frequency in order to avoid aliasing in the reconstructed signal. My question is that in ...
2
votes
2answers
116 views

When calculating the Nyquist frequency should carrier frequency be included

This isn't my field, so please forgive any misnomers on my part. I'm looking into buying a amateur radio receiver, and I'm thinking about what sampling rate I need. I'm most interested in satellite ...
1
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1answer
210 views

The Nyquist-Theorm behind the fft

I saw a code in Python in the scipy.org (http://docs.scipy.org/doc/scipy-dev/reference/tutorial/fftpack.html) and found this: First question: Is it right that T = 1/800 <==> fs = 800 Hz fulfill ...
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1answer
129 views

why Sampling with higher than nyquist frequency is causing aliasing?

fm=20000 and I am sampling following signal at 65000 Hz: ...
0
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2answers
92 views

Relationship between Fs (the Nyquist frequency), and the frequency used with a sine wave

Say you are given a vector t =[...] for the time to be used to generate a sine wave of a certain frequency say FHz. I have all the data for t so I can conclude what dt is (my dt = 1d-5). Now I am to ...
0
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1answer
44 views

Basic sampling problem - could use some advice

I have a problem in my DSP class that I could use some advice with. An analog signal of length 2.5s is sampled with a Nyquist frequency and the sampled sequence has 5001 values. What is the highest ...
1
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1answer
97 views

Can I ignore the Nyquist criterion?

If I have a signal with frequencies up to 2000 Hz but I'm only interested in the frequency range up to 500 Hz, is it correct to sample at 1000 Hz $(f_\mathrm s \geq 2 \cdot f_\mathrm{max})$? Or do I ...
0
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0answers
173 views

Recording square waves at sample frequency

For a project I am working on, I need to incorporate GPS data into an audio file. As things currently are, the easiest way for me is to record the audio in a multi-channel .wav file, and add the GPS ...
0
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2answers
81 views

Minimum Samples Per Chip?

Is there a 'Nyquist Criteria' for the minimum samples per chip that are needed for a correlator? I've heard 2, but will 1 work? What are the implications of having less than the minimum (in the ...
1
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1answer
101 views

How to determine Nyquist Rate

I have the Fourier Transform of a signal. How can I determine the Nyquist Rate of that signal? What is the formula for that?
1
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1answer
112 views

Is phase and amplitude information necessarily lost when undersampling?

Is phase and amplitude information necessarily lost when undersampling if you have a constant periodic single frequency sinusoidal? My second question is: How can one determine the undersampling ...