# Questions tagged [wave]

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### Envelope of a series of pulsed signals [duplicate]

I need to record a series of pulse waves for an experiment. The recording is done via Software Defined Radio (GNU Radio). The pulse waves are modulated in such a way that the amplitudes of each single ...
• 11
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### How to obtain the wave height "H" /wave period T from the spectral density S(f)

I have the equation of the power spectral density $S(f)$. I seek $(H,f)$ of each sinusoid which $H$ is the magnitude and $f$ is the frequency. How to calculate $H$ from $S(f)$? $S(f)$ is the spectral ...
37 views

### How to inject a 2D plane sine wave to the array of seismic sensors?

I've several sensors positioned at various points in the $X$,$Y$-Cartesian coordinate system, and I've experienced a problem to inject a planar Sine wave to the spatially positioned sensors, the ...
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1 vote
19 views

### What is meant by discrete time plot with Whatsapp voice notes? [closed]

You might have noticed ,as shown highlighted in attached snap, whatsapp voice notes are bearing a discrete time plot Is it exactly referring to sampled(discrete time)version of waveform of actual ...
• 811
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### Finding the mode of propagation of a progressive wave and the velocity of that mode

Injecting a sinusoid say, $Z = A \sin(k_x X + k_y Y - \omega t)$, $K = 2 \pi f/c$, for example, assume $f = 10$ Hz or $50$ Hz, and $c = 50$ m/s, now if I draw the 2D K-space plot with the following ...
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28 views

### step by step resolution of the homogeneous $2^{nd}$ order differential equation of the wave

I am trying to solve the homogeneous $2^{nd}$ order differential equation of the wave : $\nabla^{2}\sigma-\frac{1}{v^2}\frac{\partial^2{\sigma}}{\partial t^2}=0$ In particular I want to solve it for a ...
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269 views

### How are sounds recorded and reproduced (played back)?

Someday I have suddenly got wondered how sounds are recorded and reproduced. I searched a little bit but the information I got was composed of difficult words and contents, so I couldn't understand ...
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76 views

### Why can't millimeter waves travel far [closed]

So I was digging around 5g technology, and apparently, many people say that high-band 5g can't penetrate buildings, trees, even rain. However, the atmospheric attenuation around 30 GHz does not seem ...
• 123
798 views

### How to extract the dominant frequency from the audio WAV file using numpy

So, I recorded this audio on my phone while I was running a tone generator on my PC at a frequency of 13Khz, now I want to extract this frequency which is dominant from the recorded ...
115 views

### Why does a wave composed of two waves have an FFT with only one peak?

I am trying to find a value from a given mathematical function whose input is supposed to be derived from FFT components. Essentially, I follow the procedure from [1] which assumes that a given sine ...
43 views

### Reflected wave in FFT?

I'm trying to determine the reflective coefficient of sine wave. This one paper suggests a method using Fourier analysis. Here, it suggests Incident Wave = a cos(kx + Constant1), Reflected Wave = a ...
1 vote
27 views

### Resources for the Basics on Signals and Electromagnetic Waves in the radio frequencies [closed]

What are some good books and videos, to learn about radio waves? For someone (me) who has never studied Math, Physics, or anything people generally consider ‘technical’.
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### Wave Digital Filter Bridge-T Resonator implementation, gives expected cutoff frequency but incorrect gain and roll-off

Trying to implement the WDF in Fig 5(a) of this publication. The response of the ideal op-amp implementation is given by the black curve in Fig 7: Here is the plot I get when trying to implement the ...
91 views

### Efficient Method for Interpolating between bins in FFTW

I'm working on some oscillator classes right now and perform FFT around 100 times per second. The issue I'm running into is interpolating between the bins so there is not a noticeable change from each ...
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47 views

### Playing sounds with only one frequency at a time

We have a "speaker", that can make a single frequency at a time (0 - 130k Hz). So we can play a tune by making it play a tone for 1 sec and then the next tone for 0.5 sec etc. We can change ...
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1 vote
70 views

### Hello World Example of a Digital Waveguide in JavaScript

I am just learning about sound so might be jumping the gun a bit. But it helps me stay motivated and get into an interesting problem to solve to ask these more complicated questions. I am looking at ...
• 111
75 views

### What do troughs represent in a sound wave?

What's the notion of negative amplitude? I hope the title and the question don't mean different things.
317 views

### What is the actual format of this audio file?

I am collecting some data from jotform .wav widget. All the audio files are in .wav format. But when I tried to open the file using python ...
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1 vote
64 views

### How does voice affect a sound wave or its corresponding waveform?

Someone in the physics stack exchange told me to come here for this question. My question is how does a person's voice affect how a soundwave looks? For example, if I say the letter "a" it ...
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164 views

### Does Radio Communication Have to Account for the Doppler Effect?

I know that radio communications take place in specific frequency bands, and that the doppler effect can cause shifts in frequency when there is relative motion between the source and destination ...
62 views

### harmonic waves as integer multiple in spectrum

i have a motor that is rotating with a certain frequency. If i check the frequency spectrum it contains a peak on 150 hz. Also i have peaks at 300,450,600 ... i guess that those peaks are harmonics. ...
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506 views

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1 vote
437 views

### Types of interpolation used for reconstruction in DSP?

What are the different types of interpolation used in DSP for reconstruction of analog signal from discrete/digital signal I am able to somehow learn two types of interpolation 1st is "zero order ...
• 948
115 views

### How to Save FFT output for fast read-in?

For a project, I'm reading in hundreds of short (4 sec) wavefiles and giving them to scipy fft for the frequency information for further processing/experimenting in various ways. Problem is, I want to ...
1 vote
18 views

### Digital signal processing how audio wave and function chage with respect to each other

If an audio signal is f(t) and if i play same audio with 2× speed then what will function of 2× speed signal f(2t) or f(t/2) and why?
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97 views

### Mix N sinusoidal waveforms without clipping but at a costant amplitude with no clipping and maximum amplitude

I need to mix "n" sinusoidal waveforms which can be all active or some or all can be silent. The math seemed simple (working with float32 samples) because I just added all waveforms and then divide ...
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107 views

### Clip wav by PSD

I have the following two things. sequence_1: Sound file in the wave format. PSD_1: Some PSD (Power Spectral Density). I want that the PSD(sequence_1) < PSD_1 for all indices. How I think about ...
1 vote
115 views

### Where should triangle, sawtooth and square waves start?

I am reading a text on DSP, which shows generation of sin, cos, triangle, sawtooth and square waves. Generated cos waves start at 1 and sin waves start at 0, which makes sense (cos(0)=1, sin(0)=0). ...
• 115
58 views

### Need help with detecting onset of audio in wav file

I'm new to DSP and I'm learning as I go. I have an audio file with a chirp signal(2kHz). I played and recorded this chirp signal and the recording has a lot of environmental sounds. Here is my code:
276 views

### Why do waveforms that are symmetrical above and below their horizontal centerlines contain no even-numbered harmonics?

All About Circuits site states that waveforms that are symmetrical above and below their horizontal centerlines contain no even-numbered harmonics. Can somebody explain this mathematically, or point ...
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### are Ultra sound signal amplitude dangerous? [closed]

First sorry if this question if it's out of topic but I'm very intrigued The human ear can hear a specific range of sound waves frequency. and huge amplitude of those sounds can damage the ears but ...
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### difficulty in understanding amplitude, frequency and period

I have difficulty in understanding of some fundamental terms as amplitude. Can be there more than one amplitude for a signal? The following expression is combination of 3 sinusoidal signal, so are ...
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195 views

### Is it possible to encrypt an audio wave? NFL Example

In the NFL, quarterbacks receive playcalls from coaches over their helmet's wireless interface. Someone mentioned how occasionally, these radios will pick up interference from airplanes, and that ...
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94 views

### frequencies in sound: multiple possibilities?

First, I am by no mean a sound engineer (as you will guess later). I was just wondering something while looking at the waveform of a .wav for a given shape of waveform on a duration of 2 sec for ...
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4k views

### Extracting metadata from wav files [closed]

I was curious if there is a way to extract metadata from wav files. For instance, can you get bpm, key, instrument, etc. from a .wav file on upload?
158 views

### How to Extract a Period of a Periodic Pulsed Signal?

I rercorded a sequence of zeros and ones which is repeated many times. However, the first and the last repetitions may not be complete because I have to start recording at a random time, so the ...
273 views

### Windows Audio WAVEFORMAT buffer BYTE to 16-bit int

I am trying to understand audio-buffer processing at the low-level for the first time. I have the following C++ code copying WAVE-format byte data from capture buffer of Window Core Audio (*ppData in ...
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277 views

### How to compare two audio files that maybe have been recorded in the same environment

I have two audio files that I think they were recorded in the same room. Is there any tool that can be used to compare both of them. Knowing that sample rate and format are the same. Thanks
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299 views

### Equation for impulse train

I am looking for a formula (Fourier series) to generate an impulse train waveform - a spike-wave with amplitude and period both $1$ – so that $f(x)$ has value $1$ at $x = 1,2,3,4...$ and $f(x)$ has ...
9k views

### Mathematical equation for the sound wave that a piano makes

Is there a mathematical function that can output the sound that a piano makes at different frequencies? So if the simplest equation for a sound wave (at a given frequency and for a given sample rate) ...
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### Pitch fluctuates unexpectedly in simple sine function

I wrote a very basic C program to play a sine of a user-specified frequency. In the interest of portability, I have it spit values directly to stdout, so hopefully you can reproduce my problem on your ...
1 vote
169 views

### When simulating a voltage divider using wave digital filters I get inversed polarity outputs

I'm studying wave digital filters for my bachelor's thesis and I'm finding problems in implementing a voltage divider to test my knowledge. Here's the circuit that I'm trying to simulate and the WDF ...
1 vote
274 views

### wavwrite with 32 bits per sample seems to overflow?

I am trying to generate a 32bit PCM wav file with octave, the file shall contain a single full-scale sample (0db impulse). I am getting the expected result when using 24 bits per sample: ...
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1 vote
71 views

### Is there a special case in which wave atoms convert to curvelets?

I'm new to multi scale transformations. I was wondering if there is a special case where wave atom converts to curvelet transform? Can I use wave atom parameters to have curvelet properties?
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### How to triangulate 2 sources on a 2d plane formed by 4 sensors?

I have 4 sensors capturing signal data. Signal distribution speed is constant and known. I have sensors positions in 3d space. Also, I have an amplitude/frequency decomposition for data received by ...
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