EMG shields - powerline noise

[caro]

Hello,

We've recently purchased 2 Olimex EMG Shields and have been trying to use them with an Arduino Duemilanove board - we've sent output to ElectricGuru and Matlab, but we just seem to be recording high-amplitude 50-Hz powerline noise.  The noise amplitude drops slightly when we connect the electrodes to a person in appropriate places, but not as much as expected - and not enough for us to see a signal, even an ECG.

Can you suggest where we should be looking for the source of the problem?

We're using your suggested code to connect to ElectricGuru and have followed the setup instructions exactly - to the best of our knowledge.  But we're new to this, so any advice gratefully received!

Many thanks in advance
Caro

[LubOlimex]

Hey Caro,

It is impossible to filter the utility frequency 50Hz (60Hz in Americas) completely on an embedded board. If you want to remove the 50Hz hum forver I'd suggest to use impulse powering. Easy way to do so is to power your Arduino Duemilanove and the ECG/EMG shield from a charged laptop that is disconnected from the AC socket.

Best regards,
Lub/OLIMEX