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# Questions tagged [frequency]

Frequency in signal processing is the number of cycles (of the signal) per second.

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In the literature, the instantaneous frequency for a signal $s(t)=e^{-j \phi(t)}$ is given by: $$f(t)=\tfrac{1}{2\pi}\frac{d\phi(t)}{dt}$$ This my problem: I have a signal $$u(t)=e^{-j \alpha_1 \phi(... 2answers 30 views ### DFT frequency resolution exercise I have a discrete signal that goes as follows:$$x[n]=[-1,4,-1,0]$$I have already done the DFT for the signal, with the following result:$$X = 2, X=-4i,X=-6,X=4i$$But for some reason, I ... 1answer 11 views ### Modal analysis and frequency response function - interpretation needed For couple of weeks now, I have been trying to measure cutting forces during machining processes. The system which I am currently examining is highly distorted at high frequencies due to its ... 0answers 14 views ### In an automotive ECU application for STM32, what ADC modes should I use? [migrated] I am writing an application for the STM32f407-Discovery board that will use the ADCs present on it. I want to have access to all 17 of the input channels, and I will be using the HAL library to write ... 0answers 29 views ### FFT first frequency I have some problems understanding FFT. If I know Fourier analysis frame (1024 samples) and sample rate (48 000 Hz), how can I find the first frequency of harmonic sines and cosines? 0answers 16 views ### Measuring respiratory rate from a 3d accelerometer signal? How do I preprocess this data and move forward with it? I have read a decent amount of papers that used wrist smartwatches to measure respiratory rate, or papers that used sensors attached to a persons chest. I can link them if it is necessary. I am ... 0answers 7 views ### Physical meaning of a signal with 4 IMF? If a signal is composed of four implicit mode functions, where the last one is a constant residue, does the instantaneous frequecy of the signal have physical meaning? 1answer 50 views ### Scaling Function in Wavelet Analysis I was watching a YouTube tutorial on wavelets https://www.youtube.com/watch?v=wgRgodvU_Ms, where the presenter showed that if we multiply a Gaussian with a sine wave (and follow some other conditions),... 1answer 42 views ### with given Sampling rate, what max frequency human voice can be captured? I'm new to signal processing and sampling rate, I was asked interview question related to this. This is the exact question asked: With 8Khz of sampling rate, whats the max frequency that human ... 1answer 45 views ### Sampling of frequency response Let's consider any physical quantity depending on the frequency. For example, the impedance of a certain electrical component: Z(f). Now, imagine to measure it in a continuous interval of ... 2answers 54 views ### What Is the Bilateral Filter Category: LPF, HPF, BPF or BSF? I`m reading about Bilateral filter with images, I knew that it uses Gaussian filter (which is a LPF) as a domain filter plus a range filter and it is used to preserve edges(high freq component). Can ... 1answer 37 views ### How does one interpret an element of the “transfer matrix” used to calculate frequency domain granger causality (via VAR models)? I am attempting to gain a better mathematical understanding for how autoregressive models can be used to infer frequency-domain granger causality. All freq. domain measures of causality that utilize ... 1answer 66 views ### Tracking a sine wave with noise This will probably be an extremely simple question for some one with any background in signal processing(not my background) Let say I have signal$$x(t)=A\sin(\omega t)$$where A is known and \omega... 1answer 61 views ### White noise in range of frequencies [duplicate] If I have this function: while (true) { frequency = 8000; wave = sin(sampleNumber*2*PI*frequency/sampleRate) sampleNumber++; } it will produce an ... 0answers 20 views ### Difference between OFDM and FDM In Frequency Division Multiplexing we provide one channel to one user. Example like BandWidth of user1's voice is 200Khz. I provide one channel of 200KHz in FDM for uplink as shown in the figure. ... 1answer 25 views ### How to calculate bitrate of PAL? I have to calculate the bitrate of PAL format \ (576*720) . I have the following data: \ 25  frames per second Interlaced Interior representation is: \ 4:2:0  \ 8  bpp I have tried the ... 1answer 48 views ### DC Components and Frequency I have started learning digital communication and was on line coding. I read there are certain characteristics that we need to keep in mind while choosing the right line coding method. One of these is ... 1answer 23 views ### relationship of frequency with range in Underwater acoustic channel I am interested to know what range of frequencies can be used/ or are effective for wireless communication, within the underwater acoustic channel. I do know a table exists from \cite{... 0answers 118 views ### How do I find the peak frequency of a wav file in python? I am fairly new to python and signal processing and I was given a task to record audio for 'x' seconds and then find the peak frequency in the audio file. So far I have successfully implemented the ... 1answer 49 views ### DFT and integer valued basis functions'sf requencies In Matlab the function W=dftmtx(N) gives the DFT matrix of size N. Each row is computed for an integer frequency k. W_{k,n} = e^{-i2\pi kn/N}, k-th frequency, ... 1answer 67 views ### Correlation between frequency and initial phase estimates using FFT Why is there a high negative correlation between frequency estimation errors and initial phase estimation errors when measured using FFT? I have a simple code showing this negative correlation. is ... 1answer 106 views ### Power and Energy of an Audio file I have a question about calculating the power and Energy of an audio recording. I have imported a waveform of an audio recording in WAV format into Matlab and then calculated the energy and power in ... 0answers 44 views ### Aliased Signal's Frequency So I have an incoming signal of 137.9 MHz and a sampling frequency of 1.4 MHz. Once sampled how do I calculate the aliased ... 1answer 28 views ### Digital carrier recovery I was reading Chapter 2 from "Telecommunication Breakdown" by Johnson and Sethares and came across this paragraph: However, sometimes it is more cost effective to perform certain tasks in analog ... 0answers 140 views ### Butterworth cutoff frequency normalization The issue: I am trying to reproduce the step detection technique as described in this paper. You can see the proposed step detection in the image below. The first part of this technique is to use a ... 1answer 68 views ### Is there a good method to extract a reference sin/cos from a group of signals? For the removal of a pure interference from a group of sampled signals, if I know the exact frequency of the interference I can simply use an I/Q demodulation technique (i.e., a phasor projection) to ... 1answer 53 views ### STFT output frequency does not match sin wave frequency I have the following function and pre definition for producing a sin and its' stft: ... 0answers 67 views ### How to find frequency and corresponding time for an audio signal? I want to read in a sound file and get the frequency at each time interval of the signal. I thought that the best way to approach this is by applying FFT to small chunks of the signal. Because FFT ... 1answer 47 views ### Calculate aliasing of x_a(t) = \cos{(2\pi300t)} + \cos(2\pi600t) when sampled with F_s = 1000 I'm asked to sample the signal$$x_a(t) = \cos{(2\pi300t)} + \cos(2\pi600t)$$with sampling frequency F_s = 1000 and plot the magnitude spectrum for the resulting sampled signal. My thinking is ... 1answer 106 views ### What does a fractional frequency (for discrete-time signals) mean/how to interpret it? [closed] This question has bugged me for a while as it's not addressed in any books I've read. I was wondering how folks from this community interpreted it. Below are my personal notes on the matter (please ... 0answers 21 views ### Is it possible to create a causal filter with a positively-sloped phase response? I am currently prototyping a set of noise-cancelling headphones that utilize active EQ to modify the noise-cancelling signal, allowing the user to modify the frequencies that they hear or don't hear. ... 0answers 52 views ### Practical Signal Processing by Mark Owen Exercise 2.1. and 2.2 The following exercises don't have answers in Practical Signal Processing by Mark Owen. What is the author looking for here? A mathematical proof? 2.1 A cosine wave of frequency f is sampled at t = ... 0answers 12 views ### Complex Spectral Phase Evolution (CSPE) Performance depending on signal windowing? I am look into CSPE. "Signal Analysis Using the Complex Spectral Phase Evolution (CSPE) Method" The method is simple. It compares the original signal's FFT and shifted signal FFT in phase domain so ... 2answers 225 views ### Do Fourier frequencies actually exist in real life in form of “fundamental frequency”? For me, this is a very awkward question to be asked, as at this point in my studies I'm supposed to be quite expert with elementary mathematical tools like Fourier transforms, but this has always ... 0answers 16 views ### Interpreting results of multiplying signal and wavelets in the frequency domain I have followed a lot of stuff on mike cohens website and have managed to make a filterbank of Morlet wavelets and convolve with an incoming block of samples. This of course is a computationally heave ... 1answer 88 views ### Term for integral multiples of fundamental period? As we know that a signal has fundamental frequency and integral multiples of fundamental frequency are known as harmonics I am curious about the term that will be used for integral multiples of ... 1answer 96 views ### Formant Analysis Frequency - What makes a peak value? from spectrograms, how can you tell which peak is really a formant. Like why is the pink arrow the first formant. And in the spectrogram below, which has fewer samples, what makes a value the peak ... 1answer 287 views ### Chebyshev I or Chebyshev II? I am new to DSP, and I am trying to recreate some analysis of a signal, They use a chebyshev I filter to go from a 100Hz signal to a 50Hz signal. Whereas I am currently using a chebyshev II filter, ... 0answers 42 views ### histogram bin size vs. data sampling rate I have a set of numerical signals that give me a set of zeros calculated based on some numerical procedure. I make a histogram of those zeros. Here, a following problem arises: If the histogram ... 2answers 383 views ### In case of using a Doppler radar, do we have to use IQ demodulation to find the direction of a target? I want to know the way to find the velocity of a target by using a doppler radar. I read some paper about it, In summary, send rf signal to a target receive the reflected signal from the target. ... 1answer 81 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: ... 2answers 141 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. 1answer 100 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 ... 4answers 1k 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 ... 0answers 32 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 ... 0answers 9 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 ... 0answers 24 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.... 1answer 306 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 ... 2answers 301 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 ...
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 ...