Questions tagged [frequency]
Frequency in signal processing is the number of cycles (of the signal) per second.
0
votes
1answer
22 views
How do I find the frequency of a particular bin in a cosine transform, and two other questions
I have a discrete series of values and I have applied a Discrete Cosine Transform to it, obtaining values like:
...
0
votes
2answers
38 views
May I know how to find Time frequency power spectrogram of a signal?
I am analyzing EEG signal and I am unable to understand the term Time-Frequency Power Spectrogram. Please Can anyone help me?
Thank you in advance.
1
vote
1answer
73 views
How is frequency related to data rate?
How does (if it does) frequency affect/relates to Data Rate.
Why for example using the same modulation, LoRa (in the physical layer),
you get somewhere around 250kbps at 2.4Ghz and only 20kbps at ...
-1
votes
4answers
91 views
What are real-valued and complex signals and why is the Fourier transform of a real-valued signal Hermitian?
I have confusions in these concepts:
What are real-valued signals?
What is the difference between it and complex signals?
Why is it so that for real-valued signals, the spectrum of negative ...
0
votes
0answers
28 views
Temporally locating beats in an audio file
Imagine you have a long recording of a guitar player playing an arpeggio at a slow speed. To simplify, assume the tempo is 60 bpm or lower. I want to annotate this recording with the exact moments ...
0
votes
0answers
8 views
user multiplexing in NOMA system
when two users are multiplexed in downlink noma system using the same subcarrier i,the throughput can be expressed as
How to form the throughput expression in downlink noma system when two users ...
0
votes
0answers
12 views
Downlink NOMA system
In what manner does subcarrier,frequency,channel are related in downlink NOMA.
How does the subcarrier allocation takes place when users are getting grouped into clusters on the same frequency....
1
vote
1answer
94 views
What is the relationship between angular frequency and normalized angular frequency
This is a slide from my lecture notes:
My professor used the following words " We denote digital frequencies with capital letters and analogue frequencies with lower case letters"
The problem I have ...
0
votes
2answers
40 views
Noise power and bandwidth
$$N=kTB$$
In this formula for calculating noise power, why do we use the total bandwidth of the system?
I mean our signal is at $f_0$ carrier frequency, why is it effected by a large bandwidth and ...
0
votes
1answer
24 views
Frequency spectra of a sampled process
I have a process $X$ with frequency spectra
I sample this process with sampling frequency $f_s = 2$.
What will the frequency spectra $R_z(f)$ of the sampled process $Z$ look like? I realize that ...
0
votes
2answers
83 views
How to increase resolution of FFT?
I have an input signal in the ( 0 - 20 kHz ) frequency range . When i sample this signal maximum sampling frequency is around 40 kHz . When i calculate the FFT using 1024 points i got resolution of ...
1
vote
0answers
52 views
Best Way to Extract Frequency from Signal [closed]
I want to send signal that compound from 16 different frequency over GSM.
The problem is the GSM network is very noisy and I have only 400-3400 hz frequency available for use.
I try using fft ...
1
vote
0answers
57 views
The Definition of Q Factor by an Equation and How to Graph
I am currently building an EQ in an music app, and it's relatively simple:
6 bands of fixed center frequency, and a Q knob to control the Q of all bands, because we do not currently have space for ...
0
votes
2answers
35 views
How to make sure that a sinusoid wave with different subsequent frequencies matches up?
A very basic formula to transform a sequence of notes into a signal would be:
$$
x(t) = A\cos( 2 \pi (2^{current\_note}/12) t)
$$
where $current\_note$ is $notes[\lfloor t / period\_per\_note\...
0
votes
1answer
47 views
Why do we use normalized angular frequency?
Let's say we want to generate a signal in MATLAB, using sin, representing the A-major chord (440 Hz, 550 Hz, 660 Hz, each with amplitude 0.1).
I know we have to use the normalized angular frequency. ...
1
vote
1answer
46 views
Visualising OFDM subcarriers in the frequency domain
Im struggling to understand why in some images the frequency domain shows clear bars with amplitude and phase and with 0 frequency variation (it is clear that the frequency of the waves does not ...
0
votes
1answer
42 views
What is normalized angular frequency? [duplicate]
I am new to DSP, and I am self-studying. I came upon this question, and I am stuck at it. Could someone please help me? Here is the question:
In order to digitally create a sinusoid with frequency $...
0
votes
1answer
384 views
Write a 440 Hz Sine Wave to .wav-File using Python and SciPy [closed]
This is my first post on DSP.SE! I'm a student in Computer Sciences and am just getting started with Signals and Systems, thus getting in touch with discrete signals and analyzing them.
I wanted to ...
0
votes
1answer
63 views
How can I get the power of a specific frequency band after FFT?
I need help with my matlab code. I have recorded EEG data and now I want to analyse it in matlab. I want to find the mean power of specific frequency ranges (theta: 4-8 Hz,alpha: 8-12Hz etc.). For ...
1
vote
1answer
77 views
Why a DFT of two sinusoids is very noisy even with frequency sampling 5 times higher?
I've set up this case to try to understand DFT implementing a real case in Excel
Frame Size $\;\color{blue}{(T = 5 \; s})$
Time Sampling $\;\color{blue}{(T_S = 0.1 \; s})$
Block Size $\;\color{blue}{(...
0
votes
2answers
47 views
Why is it called continuous-time frequency?
I'm just wondering about the CTFT. My lecturer refers to capital Omega $\Omega$ in the following as being the continuous-time frequency:
Why is it called continuous-time frequency here but in the ...
1
vote
1answer
50 views
Break a signal into segments, add them together and then perform an FFT on the result
If you break a 4 second signal into 0.5 second segments, add them together and then perform an FFT on the resultant 0.5 second data.
Will the FFT / frequency spectrum be the simlar to an FFT on the ...
2
votes
0answers
105 views
Frequency translation with FFT
I'm new to DSP and I would like to make an SDR receiver. For this I want to shift bins in the frequency domain in order to bring to 0Hz any portion of the base band spectrum (I know that there are ...
1
vote
2answers
121 views
Carrier Frequency Offset, Rotating Constellation and Correlator
I have been further reading up on carrier recovery methods and something is not clear to me:
It's written that a carrier frequency offset results in a rotating constellation diagram but if you are ...
0
votes
2answers
573 views
What does it mean for a function to have frequencies?
In a lecture, my professor mentioned that $\cos$ has two frequencies. I see that using the inverse Euler's formula we can express $\cos$ as a some linear combination of complex exponentials, each with ...
0
votes
2answers
113 views
Why do frequencies of analog signals range from $-\infty$ to $\infty$ while frequencies of digital signals are restricted to $[0,2\pi]$?
In Fourier analysis while dealing with discrete-time signals, frequencies range from $0$ to $2\pi$ why? Intuitively how can i understand it?
1
vote
2answers
70 views
Relating phase difference in a signal with its frequency
I have a 134 point complex signal. Using MATLAB, I have observed that the phase difference between any two adjacent samples of this signal is 2 radians i.e. the phase increases linearly from 0 to 268 ...
1
vote
1answer
34 views
Intuitive understanding of frequency
I know that $f = \frac{\text{cycles}}{\text{unit of time}}$ and I know that period $T = \text{time it takes to complete one cycle}$.
So if we take the definition
$f = \frac{1}{T} = \frac{\text{1 ...
0
votes
2answers
56 views
I'm confused about the notion of frequency when it comes to arbitrary data
In signal processing class we keep learning about how it's so useful to bring things into the frequency domain instead of the time or space domain but I'm very confused about what the motivation is or ...
0
votes
1answer
56 views
How range of the signal increases when modulation is done? [closed]
I am very confused because we know by increasing frequency we decrease the wavelength hence the distance covered will be very less but when we modulate a signal we are basically increasing the signal ...
2
votes
2answers
217 views
Can the instantaneous frequency be always derived from an analytic signal?
Instantaneous frequency can be defined as a derivative of an instantaneous phase of an analytic signal which can be nicely seen in practice in this example from Scipy's documentation. But it seems ...
-3
votes
1answer
26 views
How do I generate sine waves with MATLAB’s max operator and the plot the resulting values in dB versus log frequency? [closed]
I just start learning about matlab. Im very confuse with this. Can anyone gives me such an example solution or any kind of help?
HINT: Put the desired input frequencies in an array and use a for-loop ...
0
votes
1answer
80 views
How can I determine the order of filter?
This is my first study about signal analysing. I'm very confused about filter order. My problem is how can I know whether its 12-th order, or 2nd order like the book says so? I already knew that slope ...
0
votes
1answer
25 views
Is there just a carrier in each frequency band in FDMA?
The figure is the FDMA,and i know that FDMA is that dividing the bandwidth into many blocks(frequency band),i want to ask Is there just a carrier in each frequency band in FDMA?i mean one carrier for ...
0
votes
1answer
34 views
Modulation of real-valued signal
I have one doubt according to modulation of a real signal.
there are so many examples where the real signal was modulated with frequency bigger then 0.
Why the signal could not be putted in f=0?
is ...
0
votes
1answer
92 views
Estimation of Two Closely Spaced Frequencies?
What is the best frequency estimation algorithm for two closely spaced frequencies in term of the minimum frequency spacing achieved?
0
votes
3answers
100 views
Efficient calculation of exact frequency from a broad frequency range (1 Hz - 1000 Hz)
I have some input signal sampled at 1-10 MS/s. Let's assume that it contains one strong frequency component (with frequency anywhere in the range from 1 Hz to 1000 Hz or even higher, changing over ...
1
vote
1answer
82 views
About phase unwrapping
I am not too familiar with phase-related problems so I need some suggestions or corrections in a problem that might be an old but easy one. Here is my problem: given a complex signal:
$$y(t) = e^{j\...
1
vote
2answers
123 views
How to compute impulse and frequency response of Flanger?
I have to the implementation of a Flanger effect on Matlab, buy previously I have to plot its frequency response and impulse response.
The difference equation is $y[n]=x[n]+a\cdot x[n-d[n]]$
where $a$...
0
votes
0answers
42 views
The grid frequencies In the design of a digital filter
I want to find many difference 'h' with same group delay and length filter using this code :
https://gist.github.com/mattdsp/17f508d2b368db61f47689e4622d8841/c1518f22a5aa451951601b56c5d9f72743868bfe ...
1
vote
2answers
119 views
how to calculate the maximum obtainable directivity for a microphone array?
Introduction
The relationship between the maximum obtainable directivity and aperture of an antenna is described by:
$$ D = \frac{4\pi A_e}{\lambda^2} $$
Where $D$ is the directivity, $A_e$ the ...
0
votes
1answer
431 views
Numpy fft2 frequency shift
I don't understand how to make frequency shift in fft2 or higher dimensions. Could anyone explain it, please?
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import ...
0
votes
1answer
23 views
Non-decaying Harmonics in Vibration Signal
I am analyzing vibration data collected by an accelerometer positioned in a stamp press machine. The fundamental frequency is around 10 Hz. The problem here is that when I take the FFT of the data I ...
0
votes
1answer
51 views
How to calculate wave length
Given that 30GHz to 300GHz is considered mm wave spectrum which can be used for high-speed wireless communication such as 5G.
My question is how to calculate the wavelength if we know the frequency? I ...
0
votes
0answers
83 views
Low/High cut filter : how does it work?
I have a question about the low-cut and high-cut filter on an equalizer. Let's say, for example, that I'm using a 15 band equalizer with the following central frequencies: 25, 40, 63, 100, 160, 250, ...
1
vote
0answers
36 views
How can I design a PI controller for a closed loop system, which requires a bandwidth equal to the natural frequency and a set Phase Margin?
For a school project I have to hand in a small report on a this problem. I've been studying so much for it but right now I'm just mixing up everything I've seen and just don't know where to start. I'd ...
0
votes
2answers
46 views
Equalize Speaker using impulse response
So I have this school project where my aim is to improve a loudspeaker in general, my idea is to mesure the impulse response of the room using a mic, then use this mesure to conceive a loudspeaker ...
-1
votes
1answer
113 views
The concept of normalized frequency
This question has already been asked and answered, but the motivation behind the use of normalized frequency units still evades me.
The Discrete Time Fourier Transform $$X(\tilde{ \omega }) = \sum_{n=...
0
votes
0answers
80 views
Estimating frequency when there's little isolation between signal and noise frequencies
Say I have a signal which is guaranteed to have a frequency between 110-120 Hz but is corrupted by interference signals that're very close to this frequency range. For example, let the interference ...
3
votes
1answer
254 views
Instantaneous Frequency Estimation by Hilbert Transform - Theoretical Justification and Proof
I would like to better understand why the instantaneous frequency estimation by Hilbert transformation works (and especially why it doesn't work / lead to precise results in many cases).
The ...
