# Questions tagged [nyquist]

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### Why Matlab Spectrogram of slow and rarely sampled signal shows high frequencies

I have a signal, which was measured for 14.4 minutes (= 864 seconds). There are 192 measurements, so one measurement was done in every 4.5 seconds, which results in a 0.22 Hz sampling frequency if I ...
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### Nyquist frequency isn't working

The situation is that I have a signal with linearly increasing frequency, $$\text{sin}(2\pi\omega(t)t),$$ where $\omega(t)=a+bt$ for some $a$ and $b$, and we constantly sample at one point per second ...
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### Signal to noise ratio (SNR) of a CW signal

I understand the formula SNR = 6.02N+1.76 for a N-bit ADC which quantizes a modulated tone sampled at twice the BW. I am trying to understand what the same equation would be for a unmodulated CW tones ...
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### When do we divide by $2\pi$ while solving Nyquist problems?

I slightly lost the tempo in the course for a couple of days, so I apologies for the noob question if seemed so. Why do we divide by $2\pi$ in Nyquist problems sometimes and sometimes not? I saw there ...
397 views

### Positive and negative frequencies in DFT due to frequency folding, or due to negatively indexed frequencies?

When I look for the cause of the mirroring of frequencies in DFT output, I get two types of explanations: The first one which says the frequencies are mirrored because of the complex exponential ...