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Collect PPG data from Muse S #9

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ErikBjare opened this issue Oct 26, 2020 · 2 comments
Open
2 of 3 tasks

Collect PPG data from Muse S #9

ErikBjare opened this issue Oct 26, 2020 · 2 comments

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@ErikBjare
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ErikBjare commented Oct 26, 2020

@chatchavan
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TL;DR: I suggest using PPG2.

PPG data has three channels: ambient, infrared, red (source: muse-lsl code). Muse S has a green LED instead of the red one.

Although you have obtained data from all three PPG channels, your code currently uses PPG1.

I've logged Bluetooth packets that the iOS Muse app communicates with my Muse S while using the "heart meditation" (using XCode PacketLogger). The log shows data from only the PPG2 channel. From the sensor, only the green light appears. Therefore, I suspect that Muse S uses the green light and stream it through the PPG2 channel.

Maeda et al. (2008) correlates signals from infrared vs. green light with a reference signal from ECG. They found that green light has a better correlation than infrared. Therefore, it is possible that Muse S uses only the green light at the moment.

@ErikBjare
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ErikBjare commented Jul 24, 2021 via email

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