Apologies for not knowing the details of the physics here.
\nCan we assume the same signal trajectories between Hanford & Livingston ?
\nFor example, if the signal in Hanford at time t, is located a frequency B
\nS(t) = B Hz
\nthen the same applies for the Livingston recording (ie, there is no transformation due to earth's rotation or angle of impinging signal) ?
I understand that there could be differences in SNR and relative phase, but we can assume the signal's most intense frequency over time in the power spectrum should be the same across these two locations?
\nThanks.
", "messages": [ { "id": 1999962, "postDate": "2022-10-22T22:15:46.293Z", "content": "Apologies for not knowing the details of the physics here.
\nCan we assume the same signal trajectories between Hanford & Livingston ?
\nFor example, if the signal in Hanford at time t, is located a frequency B
\nS(t) = B Hz
\nthen the same applies for the Livingston recording (ie, there is no transformation due to earth's rotation or angle of impinging signal) ?
I understand that there could be differences in SNR and relative phase, but we can assume the signal's most intense frequency over time in the power spectrum should be the same across these two locations?
\nThanks.
", "rawMarkdown": "Apologies for not knowing the details of the physics here.\n\nCan we assume the same signal trajectories between Hanford & Livingston ? \n\nFor example, if the signal in Hanford at time t, is located a frequency B\n\nS(t) = B Hz \nthen the same applies for the Livingston recording (ie, there is no transformation due to earth's rotation or angle of impinging signal) ?\n\nI understand that there could be differences in SNR and relative phase, but we can assume the signal's most intense frequency over time in the power spectrum should be the same across these two locations? \n\nThanks.", "votes": 8 }, { "id": 2001672, "postDate": "2022-10-24T08:21:24.133Z", "content": "Hi @ikarosilva , @junkoda ,
\nThe frequency of a signal as seen by a detector a certain time t (what you call it S(t) in your post) does generally depend on the detector, the reason being that different detectors move \"differently\" around the Sun as they are in slightly different positions on Earth.
This distinction may not be that noticeable for some cases if we use the two Advanced LIGO detectors, since they are relatively close to each other, but becomes quite apparent once you include other detectors such as Virgo, which is located in Italy.
\nIn tutorial 1 you can find an example on computing the instantaneous frequency of a signal in a given detector. If you are interested, I would recommend running such an example for different detectors (H1, L1) and see how a specific signal changes its evolution.
Alternatively, @junkoda 's method of plotting strong signals is also a quick and safe option 👍.
", "rawMarkdown": "Hi @ikarosilva , @junkoda ,\n\nThe frequency of a signal as seen by a detector a certain time t (what you call it `S(t)` in your post) *does* generally depend on the detector, the reason being that different detectors move \"differently\" around the Sun as they are in slightly different positions on Earth.\n\nThis distinction may not be *that* noticeable for some cases if we use the two Advanced LIGO detectors, since they are relatively close to each other, but becomes quite apparent once you include other detectors such as Virgo, which is located in Italy.\n\nIn [tutorial 1](https://github.com/PyFstat/PyFstat/blob/master/examples/tutorials/1_generating_signals.ipynb) you can find an example on computing the instantaneous frequency of a signal in a given detector. If you are interested, I would recommend running such an example for different detectors (`H1`, `L1`) and see how a specific signal changes its evolution.\n\nAlternatively, @junkoda 's method of plotting strong signals is also a quick and safe option :+1:.", "votes": 3 }, { "id": 1999970, "postDate": "2022-10-22T22:43:55.860Z", "content": "I don't know the details of gravitational wave detection, but we can check by generating simulated data with very strong signal, e.g., 'h0': 1.0.
\nYes, as far as I see a few data, the frequency bin with maximum amplitude is almost the same between H1 and L1. There could be a little difference due to small difference in earth rotation doppler shift.
\nThere are large differences in amplitude and phase, which I don't know well. I guess the orientation of the detector is different and the wave is projected to two different modes.
", "rawMarkdown": "I don't know the details of gravitational wave detection, but we can check by generating simulated data with very strong signal, e.g., 'h0': 1.0.\n\nYes, as far as I see a few data, the frequency bin with maximum amplitude is almost the same between H1 and L1. There could be a little difference due to small difference in earth rotation doppler shift.\n\nThere are large differences in amplitude and phase, which I don't know well. I guess the orientation of the detector is different and the wave is projected to two different modes.\n\n", "votes": 2 } ], "comments": [ { "id": 2001672, "author_name": "Rodrigo Tenorio", "author_url": "", "post_date": "2022-10-24T08:21:24.133000", "content": "Hi @ikarosilva , @junkoda ,
\nThe frequency of a signal as seen by a detector a certain time t (what you call it S(t) in your post) does generally depend on the detector, the reason being that different detectors move \"differently\" around the Sun as they are in slightly different positions on Earth.
This distinction may not be that noticeable for some cases if we use the two Advanced LIGO detectors, since they are relatively close to each other, but becomes quite apparent once you include other detectors such as Virgo, which is located in Italy.
\nIn tutorial 1 you can find an example on computing the instantaneous frequency of a signal in a given detector. If you are interested, I would recommend running such an example for different detectors (H1, L1) and see how a specific signal changes its evolution.
Alternatively, @junkoda 's method of plotting strong signals is also a quick and safe option 👍.
", "votes": 3, "replies": [] }, { "id": 1999970, "author_name": "🐢 Jun Koda", "author_url": "", "post_date": "2022-10-22T22:43:55.860000", "content": "I don't know the details of gravitational wave detection, but we can check by generating simulated data with very strong signal, e.g., 'h0': 1.0.
\nYes, as far as I see a few data, the frequency bin with maximum amplitude is almost the same between H1 and L1. There could be a little difference due to small difference in earth rotation doppler shift.
\nThere are large differences in amplitude and phase, which I don't know well. I guess the orientation of the detector is different and the wave is projected to two different modes.
", "votes": 2, "replies": [] } ], "raw_markdown_by_id": { "1999962": "Apologies for not knowing the details of the physics here.\n\nCan we assume the same signal trajectories between Hanford & Livingston ? \n\nFor example, if the signal in Hanford at time t, is located a frequency B\n\nS(t) = B Hz \nthen the same applies for the Livingston recording (ie, there is no transformation due to earth's rotation or angle of impinging signal) ?\n\nI understand that there could be differences in SNR and relative phase, but we can assume the signal's most intense frequency over time in the power spectrum should be the same across these two locations? \n\nThanks.", "2001672": "Hi @ikarosilva , @junkoda ,\n\nThe frequency of a signal as seen by a detector a certain time t (what you call it `S(t)` in your post) *does* generally depend on the detector, the reason being that different detectors move \"differently\" around the Sun as they are in slightly different positions on Earth.\n\nThis distinction may not be *that* noticeable for some cases if we use the two Advanced LIGO detectors, since they are relatively close to each other, but becomes quite apparent once you include other detectors such as Virgo, which is located in Italy.\n\nIn [tutorial 1](https://github.com/PyFstat/PyFstat/blob/master/examples/tutorials/1_generating_signals.ipynb) you can find an example on computing the instantaneous frequency of a signal in a given detector. If you are interested, I would recommend running such an example for different detectors (`H1`, `L1`) and see how a specific signal changes its evolution.\n\nAlternatively, @junkoda 's method of plotting strong signals is also a quick and safe option :+1:.", "1999970": "I don't know the details of gravitational wave detection, but we can check by generating simulated data with very strong signal, e.g., 'h0': 1.0.\n\nYes, as far as I see a few data, the frequency bin with maximum amplitude is almost the same between H1 and L1. There could be a little difference due to small difference in earth rotation doppler shift.\n\nThere are large differences in amplitude and phase, which I don't know well. I guess the orientation of the detector is different and the wave is projected to two different modes.\n\n" } }