Recent content by mickonk

Hi milesyoung. That's FT pair from my book. Is it wrong? I found time shifting property in my book: if function is $$f(t\pm t_0)$$, FT is $$e^{\pm jw_0t_0}F(jw)$$. So FT of time shifted term would be $$e^{\pm jw(\frac{\pi}{2}+\theta)} F(jw) $$, right?

This would be (hopefully) amplitude spectrum of first and second term of input signal:

[FONT=Georgia]This my homework: Input signal to system is: where H(exp(jw)) is transfer function of ideal low pass filter with cutoff frequency wg=3*pi/4 and zero phase characteristic. Sampling in A/D converter is done with period T=(1/125) seconds. a) Calculate output signal ya(t) b)...

Here is how I tried to solve this algebraically. We have function u(n+N)-u(n-(N+1)). Let's say N is some positive number, for example N=1. 1. When n is less then -N, for example n=-2, we have u(n+N)-u(n-(N+1))=0-0=0. 2. When -N<n<N+1 , for example n=-0.5, we have u(n+N)-u(n-(N+1))=1-0=1. 3. When...

Thanks for reply. One more thing. Let's say I have some circuit with nonperiodic voltage source and I want to find response of some component in circuit, for example voltage across component. Using Fourier transform I should "convert" my excitation from time domain to frequency domain, find...

Hi. Here is one example from my book. Calculate Fourier transform of signal: Here is solution: We can write x(n) as: , where x1(n) is u(n+N)-u(n-N-1). We can write: (we used that cos(n)=(1/2)*(exp(j*n)+exp(-j*n)). Using properties of Fourier transform of discrete signal: , Fourier...

Hi. I'm familiar with Fourier series but I have some hard times in learning Fourier transform. Why we use it? What's purpose of Fourier transform? Here is one signal and plot of Fourier transform of that signal: What this graph tells us? Thanks in advance.