In the product FAQ it mentions that Muse has seven sensors. In the Hardware FAQ is references the 10-20 points (FP1, FP2, A1, A2). So my question is what do the other 3 sensors measure?
I’m not from the Muse team, just a future owner. But I think the following can help a bit:
Those 3 other sensor are used as reference sources for the 4 data sensors (like the ground in any electrical system) and also for noise supression.
Take a look at the Muse hardware description at the developer site bellow:
There is the accelerometer and the rear channels. If you want to capture ECG you can strip a usb cable and use the specific preset “13” and “15” and D- as a contact lead. There is a temperature sensor on board too but that is not exported (not sure anyone would want it). The research firmware (not released yet) can do 500hz concurrent sampling of all analog channels.
Thanks Eduardo and Matt, that is what I was looking for (and hoping for), must have missed the top level page on the hardware description (whoops!)
Matt, can you elaborate a little more on what you mean for the USB? I dont have the muse yet (should arrive today) but I thought it was bluetooth (not usb) so I’m not sueI follow. Also what is the “13” and “15” preset?
That hardware document says Muse has “1 DRL sensor at Fpz” - what is that? A google search reveals nothing useful.
Indeed, a google search for DRL brings far more references to controlling circuits of lamps in automobiles, the same acronym is used for other purposes.
Instead, do a search for “driven-right-leg circuit” and you will get a page full of references to reducing noise circuits used in biomedical instrumentation.
- from Wikipedia:
- from YouTube, a high level tutorial on the subject (more than half an hour in four videos):
I can be quite outdated, but from what I can remember since my graduation in electrical engineering (almost 40 years ago) I suppose that only one reference point is enough.
So I think that what we have is only one “reference” sensor in the center at Fpz, and two DRL sensors near Fp1 and Fp2 responsible for removing noises.
Also de two sensors behind the ears seems to be the points FP9 and FP10 (not A1, A2).
Please, don’t trust everythig I say (write). I am just trying to help with what I have been reading for the last two months, since I knew about Muse.
Anyway, perhaps this can be confirmed by reading another Muse Technical Specificatons DOC (PDF) that may be missed among the long Product FAQ page, see:
Good description of the points here…