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Results tagged with fourier-transform
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user 17721
The Fourier transform is a mathematical operation that decomposes a function into its constituent frequencies, known as a frequency spectrum.
3
votes
3
answers
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Why is the last value of an RFFT always real?
I am using numpy to do FFTs of real-valued data. And I don't understand why the Nyquist frequency is always real (or has zero phase).
So, say A = rfft(data) then A[-1] is always a real value, and not …
- 351
3
votes
2
answers
1k
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How do I convert a timeseries to a different frequency band?
I have a real time series sampled at 32 MHz. So, when I channelized it and plot it against time, I get a Frequency vs. Time image plot where the frequency domain spans 16 MHz. To elaborate, this basic …
- 351
3
votes
1
answer
894
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How does a Hermitian FFT work in Numpy?
Say, I create a Hermitian complex signal using,
import numpy as np
t = np.arange(-4, 4)
z = np.exp(1j * t)
Here z should be a complex signal with Hermitian Symmetry, as you can see below.
In [2]: …
- 351
5
votes
1
answer
3k
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How do I convert a real baseband signal to a complex baseband signal?
I have radio telescope observations that have resulted in two real-valued signals (corresponding to the right- and left-handed circular polarizations).
The signals are sampled at rate $2B$, and provi …
- 351