@@ -10,7 +10,7 @@ BBH waveform generated from Bilby can't tell the distance. We can adjust its amp
## (2) Make injection
## (3) Plot the Amplitude Spectral Density (ASD)
Plotting these data in the Fourier domain gives us an idea of the frequency content of the data. A way to visualize the frequency content of the data is to plot the amplitude spectral density, ASD. The ASDs are the square root of the power spectral densities (PSDs), which are averages of the square of the fast fourier transforms (FFTs) of the data. They are an estimate of the "strain-equivalent noise" of the detectors versus frequency, which limit the ability of the detectors to identify GW signals.
Then we consider reasonable frequency range from LIGO's detection. On the one hand, the limit of the seismic isolation systems designed by aLIGO is 10Hz, which means signal doesn't have good quality for low frequency noise below 20Hz. On the other hand, according to Nyquist–Shannon sampling theorem, for half of the sampling rate(128Hz) and above, signal's frequency is meaningless.
Therefore, set f_min = 20Hz, f_max = 128Hz, we get a new plot:
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@@ -77,7 +77,13 @@ Finally Bilby will give us BBH waveform.
In the plot, h_cross looks like a straight line, but it s correct. This is because h_cross has a very small amplitude(~$`10^-39`$) due to those angles's value.
## (5)Add white noise
For VItamin, sampling rate is locked at 256 Hz and duration is locked at 1s. Since we need a Gaussian white noise of unit variance and zero mean, here we set mean = 0, sigma = 1, and length = 256.
```
noise = mean + sigma*np.random.randn(length)
```
## (6)VItamin
Noisy data which VItamin expect actually is noisyfree data in detector plus Whitening and white Gaussian noise.
## (6)VItamin: Quickstart test
This step is to make sure that Vitamin works in the right way.
Run VItamin with test waveform provided by VItamin documentation:
