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Questions tagged [wave]

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11
votes
3answers
6k views

Determining Frequency and Period of a wave

I'm gathering temperature data from a refrigerator. The data looks like a wave. I would like to determine the period and frequency of the wave (so that I can measure if modifications to the ...
9
votes
1answer
340 views

Recognizing data clustered into shapes

I am working on a project in Python to detect and classify some bird song, and I have found myself in a position where I need to convert a wave file into frequency vs. time data. This hasn't been too ...
7
votes
2answers
1k views

Understanding values saved in WAVE file

The values that one can find in a wave file, e.g. 0.0036 0.0026 0.0174 0.0050 0.0026 0.0108 0.0154 -0.0114 -0.0006 0.0115 ...
7
votes
1answer
1k views

Why does a wave continuously decreasing in frequency start increasing its frequency past the half of its length?

I'm trying to programmatically generate a wave (sine or square) with a continuously decreasing frequency. To do so, I simply multiply the starting frequency for a decreasing value, that linearly goes ...
6
votes
2answers
10k views

Can you turn a square wave into a sine wave using a low pass filter?

And if it could, would it make the sound of the square wave thinner than before because of losing its harmonics?
5
votes
2answers
589 views

WAV encoding problem

When processing wav files, I encounter this problem: the what I extract PCM from a 8-bit encoded .wav file, I got a sequence of integers. However, when verifying my implementation with ...
5
votes
1answer
265 views

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 ...
4
votes
1answer
13k views

What do I do with the result of an FFT?

So I am working on a project using digital signal processing, which I am not familiar with at all, and a lot of this is all new to me. I am using SciPy\NumPy to play around with code to understand the ...
4
votes
1answer
255 views

Procedural wave generation, frequency shift issue

sorry for the long post but I want to try and get all the details in here in hopes it will help. I've been working on building a procedural audio system for use in XNA projects. First this is general ...
4
votes
2answers
2k views

Audio Signal Separation - Identifying Interest points

I asked this question here: Audio Separation of .wav signal but it wasn't clear, so, here is my second attempt: First off, assume that I have a .wav file containing a sentence as follows: "My name ...
3
votes
4answers
315 views

Is it theoretically possible to perfectly quantize a continuous signal?

So, I'm completely new to digital signal processing, but while reading a piece this morning about quantization it got me daydreaming: could a machine ever be fast enough to sample the position and ...
3
votes
1answer
690 views

Mathematics / Signal theory behind billiard ball 'wave pendulum' effect

This YouTube video shows a very interesting effect. What is the underlying science? I have recently started studying Fourier theory and DSP, and and trying to understand what is going on in terms of ...
3
votes
1answer
992 views

How to make pop-free, crisp two-beep ringtone?

I hope this ultra-noob question is not entirely out of place here. I'm trying to make a super simple ringtone: 0.5s silence + 1s "pure tone" + 0.5s silence + 1s "pure tone" + 0.5s silence. By "pure ...
3
votes
4answers
388 views

Why every musical instrument sounds different than any other while listening?

This is soft question.I am not expert in music. We know that English language has 26 letters (which are again grouped into vowels and consonants) , while language of music is same all over the world ...
3
votes
2answers
95 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 ...
3
votes
1answer
165 views

Problem reading and rendering Spectrum

I'm now processing PCM codes extracted from .wav file and want render the spectrum myself. First I try to read a spectrum on my foobar2000 player as below. My problem with this spectrum is: what do x-...
3
votes
1answer
11k views

Generating a noisy sine wave in Python, efficiently

(Questions after code block.) For now, I am generating the sinusoid and the noise separately and then normalising the amplitude so I can write the signal to a .wav file (16-bit, 16kHz). ...
3
votes
3answers
2k views

Removing unwanted square-wave noise from a signal

I have a signal, s, given at the end of this message. I need to remove the square wave shape from it. The desired signal is actually very small and it has been contaminated by a strong square-shape ...
3
votes
1answer
245 views

remove spatial sinusoid noise from 2d image

Given a 2D image where each row of pixels is shifted by some amount horizontally in a sinusoid fashion, is it possible to recover the original image? Imagine a camera that can capture one row at a ...
2
votes
1answer
3k views

How to obtain the Sound Pressure Level from .wav file based on these given parameters?

I have a wav file recorded from a hydrophone. I am not quite familiar with signal processing so I really need some advice from you. I have gathered the information which looks useful and related. ...
2
votes
1answer
518 views

Signals cross-correlation

I am trying to measure phase difference between two received waves which are recorded by two separate PC's (microphones). The two PC's starts recording at the same time, then I make a sine wave sound ...
2
votes
2answers
261 views

Need help with FFT results

I am playing around with FFT and cant seem to get the expected results. I have a sound clip that i recorded from a mic placed on an analogue clock. So it has a sound every second. ...
2
votes
1answer
246 views

Why LFO should be alias-free?

I'm really tripping about this point! I try to reason with you and explain what's my trouble. Consider a scenario with Sample Rate 44100hz and a LFO square wave that will modulate some internal ...
2
votes
1answer
581 views

How audio watermarks are captured

I have read that we can use audio watermarks to "identify the original produces of the material or the consumers of the media." How consumers of the media is measured by audio watermarks? Lets say ...
1
vote
1answer
1k views

How to “draw” the function/wave to send symbols using QAM?

Say you have the following 8QAM constellation diagram: Say, you want to send the sequence: 001 110 101 000 001 How would you draw the function/wave containing the symbols? My problem in ...
1
vote
2answers
1k views

Moving Average of sinusoid

If you calculate a simple moving average over a window length that is equal to the period of the sinusoid, you get a straight line (=0 because the wave is symmetric around the X-axis): the wave has a ...
1
vote
2answers
259 views

If you had supersonic hearing, would you be able to hear the carrier wave of an AM radio station?

Would you be able to hear the carrier wave of an amplitude modulated station, if you could hear in the MHz range, or would the high frequency be filtered out after rectification?
1
vote
1answer
84 views

Structure of function that describes sine signal

I need to create a vector of sine signal. So I'm trying to figure out what the structure of the function that describe sine signal ? For example the function $\sin 2x$ meets the requirements? If ...
1
vote
2answers
838 views

Band Limited Table Look Up Oscillator C++

I would like to create a Band Limited Table Lookup Oscillator that functions much like the sin() function in C++ works where i would inout a phase value and receive ...
1
vote
1answer
58k views

time in Sine Wave equation

According to Wikipedia, The sine wave or sinusoid is a mathematical function that describes a smooth repetitive oscillation. The formula for the Sine wave is, A = Amplitude of the Wave ω = the ...
1
vote
1answer
60 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). ...
1
vote
1answer
142 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
1answer
55 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?
1
vote
2answers
1k views

FFT calculation suitable, Wav File, Java

If I have a wav file with this characteristics: 16bits (2 Bytes per Sample) 32000 Sampling Rate 60 Seconds 2 Channels then I have: ...
1
vote
1answer
708 views

Does Wav format supports writing complex values

I have a sine tone, doing some math, and finally gets an harmonically accumulated sine tone in complex numbers. I do want to preserve the phase information of imaginary part on the other end, which ...
1
vote
1answer
49 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 ...
1
vote
1answer
610 views

How do you construct common waveforms (square, sawtooth, triangle, noise) from sine wave partials using an IFFT?

In the lovely image below we see the addition of sine waves making a square wave. I am coding a wave table synthesiser and thought it would be great to get the user to be able to fiddle with the ...
1
vote
1answer
171 views

Unsupervised learning algorithms to detect anomaly in waves

I have a sample of graphs (more than 10000...). that look like in the image below: I am searching for an unsupervised learning algorithms that can help me to detect anomalous observations. Here what ...
1
vote
1answer
3k views

Downsampling PCM Audio

I'm looking everywhere for solutions for audio downsampling. However for one reason or another they are incomplete, sometimes buggy, and sometimes are in a programming language I cannot understand. ...
1
vote
2answers
302 views

Bandpass filter on noisy sinusoid that predicts turning points

Is there an application where it is required to predict turning-points of a signal that is like a sinusoid with constant frequency, variable amplitude and some noise (Gaussian additive noise)? The ...
1
vote
1answer
104 views

Isolating Bat Species without prior training base

I am attempting a project and I have been given Bat calls (in .wav) which are not ultra-sound navigation calls and I'm looking to isolate the different species of bats and monitor their activity. ...
1
vote
1answer
631 views

Audio Watermarking - What is typically embedded?

Just starting research in audio watermarking and have read many papers regarding audio watermarking but I am still a little confused on what exactly gets embedded into the signal. For example, one ...
1
vote
0answers
829 views

Python: write .wav to chosen directory [closed]

I can only write .wav files to the current directory fname = 'bassswoon.wav' wav = wave.open(fname,'w') wav.writeframes(struct.pack('h', bassswoon)) wav.close() ...
1
vote
1answer
2k views

How to perform sine generation (in C)?

I am interested in how should a listing for a program look like that will generate a sine of f=50hz, using the next arguments for any moment in time. ...
0
votes
1answer
407 views

Modelling propagation of sound wave by particle simulation

How might one model the propagation of a sound wave through a 3D environment with obstacles in it? My initial thought would be to use freely moving particles that repel one another; with sufficiently ...
0
votes
1answer
43 views

In DSP - is it true that the only type of interfering wave occurs when frequencies match? [closed]

Therefore, any other frequency, no matter the amplitude, won't interfere or degrade original wave in the DSP frequency domain systems?
0
votes
1answer
423 views

Given two waves, 441 Hz and 700 Hz, how many samples long is each wave's period if the sample-rate is 48 kHz?

The title says it all. I have two waves, Master and Slave. Master is at 441 Hz and Slave at 700 Hz. The sample-rate is 48 kHz. I want to know how to calculate the period of each wave in terms of ...
0
votes
1answer
431 views

In a periodic square wave, how to change in a particular condition?

The periodic square wave, $$x(t) = 1, |t| < T_1 \\ x(t) = 0, T_1 < |t| < T/2$$ What I wonder is .. (1) If $T_1$ is constant and $T \to \infty$, is x(t) a constant function? (2) If $T_1$ is ...
0
votes
1answer
86 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 ...
0
votes
1answer
3k 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) ...