EKG/EMG too noisy

Started by YotMagnet, December 20, 2012, 02:32:22 pm

Previous topic - Next topic

YotMagnet

December 20, 2012, 02:32:22 pm Last Edit: December 20, 2012, 02:49:52 pm by YotMagnet
Hello,

I've just received the Olimex EKG/EMG shield and the EKG/EMG-PA electrodes.

I've followed every steps in the manual but the result is far from expected.

Here :


Same bad results on brainbay...

Please help...

Stan12

December 27, 2012, 09:11:13 pm #1 Last Edit: January 02, 2013, 09:35:38 pm by Stan12
What electrodes placement do you use?
I was using R+DLR on right forearm, L on left forearm. Metal plates are located on inner parts of forearms (less hair).
Keep hands close to each other, don't move  (and don't breathe :) )
The board is just a set of amplifiers, all noise is generated by electrodes/cabling system.
From your results it looks like DLR electrode is not connected.
Pls see mine recordings:
https://www.olimex.com/forum/index.php?topic=572.0

BTW, I tried snap connectors cable (see the picture in my post) and surprisingly, it works even worse.
May be, bad wires :(


YotMagnet

Hi Stan,

First, happy new year.

Thanks for your answer. For placement, I put L on left forearm, R on right forearm and D on right leg. I'll try D on right forearm as you said and maybe switch to 3V to see the difference.
Also your other post is well detailed. I I'll keep you posted...

olimex

our cable is specially made, the casual anti-static bracelets with cable have 1M ohm resistor inside the snap cap and will not work

Stan12

January 04, 2013, 11:47:20 pm #4 Last Edit: January 05, 2013, 12:00:54 am by Stan12
Hm.. has anybody mentioned  "the casual anti-static bracelets" here before? I don't quite get your comment.

Your cable could be good for resting EKG if only it has  leads long enough.


PS
Oh, are you referring to my remark
"I tried snap connectors cable (see the picture in my post) "?
Well, the cable I meant is shown in my post https://www.olimex.com/forum/index.php?topic=572.0 and IT IS NOT "casual anti-static". It is quite  usual ECG cable (although on a cheap side) designed to use snap connectors and disposable ECG electrodes. Disposable foam electrodes are most common in ECG(at least here in US).

olimex

yes stan12 your message for the snap on cable misleaded me to think that you try to use normal anti-static bracelet cable :)

MaxPaine

Hi,
The screenshot of my setup looks exactly like the posted one.
Did anyone find a solution to this problem?

Regards,
Max

TecFun

Hi there .. i also experimented with the Shield the Video: http://www.youtube.com/watch?v=uuGDnuqZqu8 is from me f.e.

I noticed that on the Screenshots theres a stable 50Hz Noise =)
So what power-source you are using to Power the Shield?! .. if its not a power-converter ... you should check if some powerline is producing this effect ... atleast a 50Hz signal is mostly produced by a bad power-supply ...