hqs_qorrelator_app.causal_fft
Functions
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Performs the Fourier Transform of a causal signal separating its odd and even part. |
- hqs_qorrelator_app.causal_fft.fft_causal(f: ndarray) ndarray[source]
Performs the Fourier Transform of a causal signal separating its odd and even part.
This way of transforming is necessary for causal signals or any signal that does not start and end at the same value. This is because the fft replicates the signal to be able to calculate the coefficients, leading to sudden jumps if the function itself is not periodic. These jumps introduce a shift in the FT at all frequencies, being equivalent to a delta within the sampled time frame. By (anti-)symmetrizing the signal one can circumvent this problem and obtain the correct Fourier Transform.
- Parameters:
f (np.ndarray) -- Function to transform.
- Returns:
The complex Fourier Transform.
- Return type:
np.ndarray