# Questions tagged [periodic]

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### Separating 'heart sound' from 'lung sound'

I have audio files recorded from electronic stethoscope and in those files I want to filter out heart sounds and retain just the breathing sounds. How can I do this using just the signal processing ...
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Let the following T-periodic signal : I found that $$x(t) = \frac{A \cdot t}{T} \qquad 0 \le t < T$$ and its Fourier series is : $$x(t) = \frac{A}{2} - \frac{A}{\pi} \sum_{n=1}^\infty \frac{\... 0 votes 1 answer 64 views ### producing sine signal with few samples I need to produce a signal of \sin(2\pi\cdot 60\cdot10^6 t), where t in sec, with sample rate of 2^{28} Hz. Since the signal has period of \frac{1}{60\cdot 10^6} sec can I somehow sample only ... 1 vote 3 answers 99 views ### How to separate Transient and Steady-State Expression from Periodic Summation Response? Background My question comes from here, it's a response of 1st order LPF RC circuit from an arbitrary periodic input. How to determine the transient response of a circuit to causal periodic inputs? ... 2 votes 1 answer 183 views ### Can time aliasing cause peaks? For the following I use the terms “time domain signal” and “frequency domain signal” as a Fourier Transform pair. The question is for generalized cases of continuous-time signals that once sampled in ... 0 votes 0 answers 15 views ### Is there any method to incorporate boundary periodic conditions into the kernel summation over unstructured data points? Supposing that there are N particles distributed inside a periodic cubic box of volume V=L^3, I want to divide the cube into a regular mesh and calculate the following summation at each grid point ... 0 votes 2 answers 64 views ### How can i get a growing sinusoid in matlab?(by incorporating real part into exp command besides imaginary part which is already there) I am trying to display a growing sinusoid in MATLAB and i know that imaginary part corresponds to oscillations but i am confused how can i incorporate real part in ... 5 votes 1 answer 98 views ### Finding periodicity in discrete events II - missions to Mars Per the Space Exploration SE question Are launch windows to Mars avoided if they result in landings during dust storm season? the synodic period of the relationship between the motion of Earth and ... 0 votes 2 answers 308 views ### Is the unit step function periodic? I am confused regarding the unit step signal. Is it considered to be periodic signal or non-periodic signal? In MATLAB we use command heaviside to implement it ... 0 votes 1 answer 91 views ### How to detect the end of a period of a repeating pattern in some time series signal I have an incoming stream of time-series data which looks like in the below figure :- I want to detect the end of each cycle in real-time (marked with red arrows) using C language. What would be the ... 2 votes 1 answer 312 views ### is this signal is perodic? What is the time period of$$ x(t) = 7 e^{\jmath(5t + \pi/2)} + 10^{\jmath(7t + \pi/5)}$$? X(t) is the combination of two functions. one is the natural logarithm base, e, and the other is 10. if ... 0 votes 1 answer 40 views ### If I have this discrete time sinusoid composed of a sine and a cosine, how do I find its period?$$ x \left[ n \right] = 3 \sin \left( 4 \pi n \right) + 2 \cos \left(0.36 \pi n \right), ~~~ 0 \leq n \leq 100 $$The fact that my signal is composed of both sine and cosine makes it tricky for me. 1 vote 0 answers 204 views ### What would be the fundamental period of this discrete-time signal? Question: x[n]= 3\cos(0.3\pi n + 0.1) - \sin(0.11\pi n -\frac{\pi}{3}) Find the fundamental period for this discrete signal. My attempt: Write the two functions as:$$\underbrace {3\cos\left(\frac{3}... 640 views

### Fourier transform of periodic functions

The Fourier transform is derived from the Fourier series by considering a non-periodic signal, thinking of it as a infinitely long periodic signal, putting it into the Fourier series and making this ...
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### How do I determine if the fundamental period $T_{x}$ exists and if so what it is?

I recently came across this $$x(t) = \cos(6t) + \sin(8t) + e^{j2t}$$ signal that I want to find the fundamental period $T_{0}$ and fundamental frequency $\omega_{0} = 2\pi f_{0} = \frac{2\pi}{T_{0}}$...
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### Period and wavelength of a noise signal?

How do I determine the wavelength of a noise signal like the one below? I find it easy to understand for sine waves, but it gets tricky for me when the signal is more complex like a noise signal. If I ...
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### Is there any rule of thumb for determining periodicity of a signal just by observation of mathematical expression?

Is there any way(rule of thumb) to determine periodicity of a signal just by observation of mathematical expression as rule of thumb mentioned in attachment for determining time invariance of a system
1 vote
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### How to calculate frequency of a periodic signal?

I know there are similar topics but I can not find any solution in my situation. I have an accelerometer sensor and a basic microcontroller. Accelerometer data is collected in an array via i2C. I want ...
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### Difference between time period formulas? Continuous time vs discrete time?

For calculating period of continuous time signal,we simply divide 2pi by omega and get period value But in case of discrete time signal, procedure is not straight forward like continuous time, ...
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### does T = 1/F always hold?

i just want to know if i use a sampling frequency of 100-110Hz and get a useful signal frequency of 50Hz (because of Nyquist–Shannon sampling theorem), is the period 1/50Hz or 1/100Hz? I've been told ...
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### How can I check if a signal its periodic from the graph of FFT?

x is a vector of length 1000 that contains the samples of the signal; n is equal to 16 that its the number of bits of each sample; fa=256 Hz (sampling frequency); <...
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### confusions regarding periodicity?

I have a sequence $x[n]=\sin(\pi n+2)+\cos(2n/3 +1)$ I want to find its period and I have also attached my working I have two confusions Is there any effect of the constant term on period? constant&...
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1 vote
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### Change in frequency on differentiation

Is there any possible periodic signal can exist(even mathematically) whose period gets change after differentiation?
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### Duality in the discrete-time Fourier series

Suppose $g[n]$ is periodic with fundamental period $N$ and $f[k]$ being its Fourier coefficients i.e. $$f[k] = \frac{1}{N}\sum_{n=<N>}g[n]e^{-j\frac{2\pi}{N}nk}$$ In more convenient notation ...
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### Ideal low pass filter output at given sampling frequency

Consider the signal $\cos(30t)$ sampled at $w_s=40 rad/s$ using a unit impulse train. The sampled signal is filtered with an ideal low pass filter with unity gain and cutoff frequency $w_c = 40rad/s$. ...
1 vote
### $2\pi$ Periodicity is not working for me for Fourier of Discrete Time Signal
please help me find the error in the following counter example. Consider we take sinus with period of $2\pi$. We sample it many time, and more than 3. We make convolution with rectangle of height 1 ...