Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [frequency]

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

The frequency of a signal is identified by calculating the number of a repeating event (a cycle in case of a signal) is accomplished by counting the number of times that event occurs within a specific time period, then dividing the count by the length of the time period.

Source: Wikipedia.

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What mathematical model of audio can make possible pitch shifting of individual notes in (timbrally complex) polyphony?

My question is: What mathematical model of polyphonic sound can make possible the changing (i.e. pitch shifting) of individual musical notes in a multi-voice-in-single-channel audio recording of a polyphonic acoustic musical instrument? By 'changing…
user1217
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Recording and playback of sound, frequencies question

If I record a sound at a rate of 8000 samples per second I know that the highest frequency that can be reproduced from the sound is 4000 Hz. What I want to know is; If the sound contains frequencies above 4000 Hz when I play the sound back what…
Sami
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Weird results out of fourier transform of unknown signal, what am I doing wrong?

It has been a long time since I studied engineering, please forgive my mistakes. I got data sampled from a digital accelerometer. It is sampled at 20 hz, then collapsed into 1 second epochs. The data is then filtered to remove noise. The system…
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Finding the input bit rate of an analogue input

Suppose I have 4 of 300bps synchronous digital input and 1 of analogue input with a bandwidth of 500Hz. The analogue input is sampled at 4bit using PCM. All the channels are multiplexed with TDM. As one of the input is of analogue, I need to convert…
xenon
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How can I calculate the frequency using different color bands?

Let's say that I have a 1 dimensional signal that has data which comes from one of 2 different spectral bands. The measurements come evenly mixed between the two bands. I'm interested in a method of extending the frequency calculation by combining…
PearsonArtPhoto
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How do I remove "jitter" when detecting frequency of Sine Wave

Input: Sine wave of any frequency centred at 1.66V Output: Square wave with a frequency equal to input I have been working on implementing a common DSP problem -- Detect the frequency of a Sine Wave. I have used a handful of posts from stack…
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How to find period/envelope that is larger than sample size?

Mercury's distance from the solar system's barycenter (in kilometers) can be approximated as: 5.9115960588705115e7 + 1.1573608483842954e7*Cos(2.086944367456105 - 0.0029751428085695573*t) based on 8 years worth of hourly "samples" from HORIZONS.…
user7409
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What does "frequency" mean for various kinds of signals?

I've been involved in Signal processing for quiet a time but I'm still so confused of what frequency could possibly is, as it has different meanings in different scenarios, for example, According to Wikipedia, Frequency is the number of occurrences…
Sufiyan Ghori
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Counting shape changing pattern in signal

I need to count the number of 'patterns per second' in a signal. The problem is that the signal changes 'shape' a lot and unpredictably. It is still easy for a person to see the the pattern, but I don't know how to do this with code. EDIT For extra…
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What is the bandwidth of human speech?

What is the actual frequency bandwidth of human speech? I know there is variation for gender, age and so, but what is the general range... I seem to find different ranges. Like here:…
Bob Burt
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Equidistant log scale points

I have an x-axis which is in logarithmic scale representing frequency, I would like to have NumPoints on this axis that are equidistant on the log scale, I have the following variables: Fmin = 100 Fmax = 4000 or 8000 NumPoints = 10 What formula…
Andy
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Nyquist Frequency

There is a statement regarding the Nyquist frequency in one of my textbooks which I don't quite follow. I would appreciate it if someone could clarify it for me. Now, the way I understand it - if we sample a signal with frequency $f_{s}$, then the…
Kristian
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Doppler effect on phase

I am struggling to find or derive the relationship between Doppler frequency and the associated phase shift. Let's say I have a signal transmitted at a given frequency $f_c$. I then down convert from $f_c$ to baseband at the receiver, but due to…
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12kHz sine or square. I can hear the difference - why?

I can hear 12kHz sinewave but not 22kHz. A 12kHz squarewave has the fundamental and harmonics I think. But the first harmonic is outside my hearing range, so how come I can hear the difference between 12kHz sine and 12kHz square? It's a long time…
Andy Oca
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Separating an audio file into "N" frequencies

I'm working on an audio visualizer using Blender, and I'm wanting to separate input audio files into their respective frequencies to allow my models to react based on the amplitude at different frequencies. Is there a Python library out there that…
Devin Gardner
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