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What is sampling frequency and Nyquist frequency?
In signal processing, the Nyquist frequency (or folding frequency), named after Harry Nyquist, is a characteristic of a sampler, which converts a continuous function or signal into a discrete sequence. In units of cycles per second (Hz), its value is one-half of the sampling rate (samples per second).
What is the Nyquist frequency for the signal?
Nyquist frequency. The Nyquist frequency is the bandwidth of a sampled signal, and is equal to half the sampling frequency of that signal.
Which sampling rate is based on the Nyquist theorem?
Nyquist’s theorem states that a periodic signal must be sampled at more than twice the highest frequency component of the signal. In practice, because of the finite time available, a sample rate somewhat higher than this is necessary. A sample rate of 4 per cycle at oscilloscope bandwidth would be typical.
What happens if the sampling frequency is less than the Nyquist rate?
As the sampling frequency decreases, the signal separation also decreases. When the sampling frequency drops below the Nyquist rate, the frequencies will crossover and cause aliasing.
How to calculate sampling rate for Nyquist frequency?
A sampling rate of 2.5 samples per cycle of the frequency of interest appears to be acceptable whereby Δt = 1/ (2.5 fN) = (2/5) (1/ fN) = (4/5) π / ωN. Enwenode Onajite, in Seismic Data Analysis Techniques in Hydrocarbon Exploration, 2014
How is the Nyquist theorem used in direct imaging?
The Nyquist theorem specifies that a sinuisoidal function in time or distance can be regenerated with no loss of information as long as it is sampled at a frequency greater than or equal to twice per cycle. The Nyquist theorem must be considered in direct imaging applications because the signal is sampled by the discrete pixel elements in an array.
Which is the maximum frequency beyond which aliasing will occur?
The maximum frequency beyond which aliasing will occur is called the Nyquist frequency. Above Nyquist frequency, seismic signal with higher frequencies are reconstructed in the form of seismic signal with lower frequencies. The highest frequency that can be successfully recovered from sampled seismic data is one half divided by the sample period.
What’s the difference between Nyquist’s theorem and Shannon theorem?
Nyquist’s theorem specifies the maximum data rate for noiseless condition, whereas the Shannon theorem specifies the maximum data rate under a noise condition. The Nyquist theorem states that a signal with the bandwidth B can be completely reconstructed if 2B samples per second are used.