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Lena/Nov 2016: Difference between revisions
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TODO: add the plot
== 11/14/2016 ==▼
=== Pregnant patient ===▼
Measured a pregnant patient, the baby is 24 weeks old. The fetal signal is visible, but the S/N is really poor. The fetal signal is about 10% or less of the maternal signal. I spent rest of the day post-processing and trying to get the maternal and fetal separated, but I can barely identify the fetal QRS complexes.▼
== 11/16/2016 ==▼
=== Pregnant patient data processing ===▼
More data processing. Checked out the signals from SQUIDs and SERFs that Ron's group have taken. The SQUID signals typically have much higher fetal signal amplitude, typically 1/3 of that of the mom for the same age. Some older babies even have the same heartbeat signal amplitude as the mom.▼
Meeting with Thad to discuss the results. Thad suggests that probably our results are getting worse over time because the room hasn't been degaussed in a long time. And SQUIDs are not affected that much because they are gradiometers. We compared the "golden baby" signals taken by Bob several years ago, and we seem to have similar maternal MCG S/N, but his baby amplitude is larger, and our magnetic noise floor is significantly larger, especially at the low frequencies.▼
Thad suggested that we take the ICA data (independent component analysis that Saki outputs) and look at the noise FFT to see how Bob's data compares to ours.▼
=== Degaussing ===▼
Zack contacted Ron, and it looks like the room hasn't been degaussed in 7 years. Thad said if the room is not degaussed, the shielding factor goes down. Zack contacted the company that installed the shielded room (ETS Lindgren) to order degaussing.▼
=== Popcorn noise in the diff/sum circuit ===
Wanted to check whether some part of the measured magnetic noise might actually be coming from the pump power noise. First we tried to stabilize the power by feeding back on the LD current, but that didn't work. The laser current was changing, but we didn't observe significant change of laser power after the tapered amplifier. The we locked the power on the tapered amplifier itself, and that didn't reduce the measured magnetic field noise. So either the room is too noisy, or the power stabilization wasn't enough.
▲== 11/14/2016 ==
▲=== Pregnant patient ===
▲Measured a pregnant patient, the baby is 24 weeks old. The fetal signal is visible, but the S/N is really poor. The fetal signal is about 10% or less of the maternal signal. I spent rest of the day post-processing and trying to get the maternal and fetal separated, but I can barely identify the fetal QRS complexes.
▲== 11/16/2016 ==
▲=== Pregnant patient data processing ===
▲More data processing. Checked out the signals from SQUIDs and SERFs that Ron's group have taken. The SQUID signals typically have much higher fetal signal amplitude, typically 1/3 of that of the mom for the same age. Some older babies even have the same heartbeat signal amplitude as the mom.
▲Meeting with Thad to discuss the results. Thad suggests that probably our results are getting worse over time because the room hasn't been degaussed in a long time. And SQUIDs are not affected that much because they are gradiometers. We compared the "golden baby" signals taken by Bob several years ago, and we seem to have similar maternal MCG S/N, but his baby amplitude is larger, and our magnetic noise floor is significantly larger, especially at the low frequencies.
▲Thad suggested that we take the ICA data (independent component analysis that Saki outputs) and look at the noise FFT to see how Bob's data compares to ours.
▲=== Degaussing ===
▲Zack contacted Ron, and it looks like the room hasn't been degaussed in 7 years. Thad said if the room is not degaussed, the shielding factor goes down. Zack contacted the company that installed the shielded room (ETS Lindgren) to order degaussing.
== 11/17/2016 ==
=== OTS cells ===
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