Q-transform projections do not show chirp signature

Data Analysis
1

I am simulating a few microlensed GW signals and trying to get their QTs using gwpy, but many signals do not show the “chirp” signature even after changing various settings of the q_transform function.

For example, I have this 8s long GW signal. I use different combinations of settings in the q_transform function (changing the qrange, outseg, whiten, norm values) :

Example setting:
ts = TimeSeries(strain_values, times=time_values, sample_rate=1.0/(time_values[1] - time_values[0]))
qt1 = ts.q_transform(qrange=(4,15), frange=(20,512),whiten=True,highpass=True,outseg=(-0.5,0.05))
qt2 = ts.q_transform(qrange=(4,15), frange=(20,512),whiten=True,highpass=True, norm=‘mean’, outseg=(-0.5,0.05))
qt3 = ts.q_transform(qrange=(4,15), frange=(20,512),whiten=False, outseg=(-0.5,0.05))
qt4 = ts.q_transform(qrange=(4,15), frange=(20,512), whiten=False, norm=‘mean’, outseg=(-0.5,0.05))

ML_00041_A
ML_00041_A1200×600 247 KB

The other combinations can be seen here

Yet, the QTs show just noise and there is no chirp signature seen.
I am using the advanced LIGO H1 (O4) PSDs for noise.

There a few other microlensed signals generated in a similar way with slightly different binary parameters which show good QT projections (clear chirp sign seen). On the other hand, I face the similar ‘no-chirp seen’ problem with a few unlensed precessing binary GW signals generated.

How do I resolve this issue?

2

Adjust frange and qrange that the frequency range is wide enough to capture the full chirp signal. Consider increasing the frange to capture lower or higher frequencies, or narrowing the qrange if the signal is highly resonant.

Try Alternative Whitening Settings with whiten=False or different normalization schemes to see if it improves the visibility of the chirp.

Modify the outseg that the analysis window includes the entire duration of the signal and isn’t cutting off key parts of the chirp.

Recheck PSD toconfirm that the noise model you’re using accurately reflects the expected noise for your simulation. If necessary, experiment with other noise models or adjust the simulation parameters.

if possible, increase the duration of the signal or boost its amplitude to improve the SNR, which may help reveal the chirp signature.