# Tag Info

Accepted

### Magnitude and phase spectrum of a periodic signal

For magnitude and phase you need the complex Fourier coefficients: $$c_n=\frac{1}{T}\int_{0}^Tx(t)e^{-j2\pi nt/T}dt\tag{1}$$ I think your Fourier series is correct, so you can directly determine them ...

### Does upsampling require a low-pass filter?

If you're linearly interpolating, there is that $\operatorname{sinc}^2 \left( \frac{f}{f_\mathrm{s}} \right)$ filtering, this puts zeros exactly on all non-zero integer multiples of your sample rate (...
1 vote
Accepted

### What does the frequency domain of bipolar Alternate Mark Inversion (AMI) look like?

Calculating the power spectrum of the AMI code is actually a quite complicated matter, but the fact that the power spectrum has a zero at DC seems intuitively clear, as already mentioned in RBJ's ...
1 vote

### What does the frequency domain of bipolar Alternate Mark Inversion (AMI) look like?

Okay, so "Google is my friend" and I found a YouTube. Bits that are zero contribute nothing to the DC component. If the number of ones in a message is even, it's as positive as often as it ...
1 vote

### Fourier transform magnitude of the sum of two signals

In general we have $$\big|X_1(f)+X_2(f)\big|\neq \big|X_1(f)\big|+\big|X_2(f)\big|\tag{1}$$ However, the condition $X_1(f)X_2(f)=0$ $\forall f$ implies that for any $f$, either $X_1(f)$ or $X_2(f)$ or ...
1 vote

### How to increase the spectral resolution?

Actually, you can achieve exact frequency retrieval from the DFT samples: Super-Resolving a Frequency Band. What is interesting is that you have an exact formula to characterize the frequency with ...

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