Need AC coupling circuit for AT-mio-64 configured in NRSE mode

[Castro]

I am using a Physiodata amplifier(for EMG recording) output as the input for my AT-MIO-64. There is a strong DC component this signal that swings slowly when the EMG signal changes its amplitude rapidly.

The AT-MIO-64 is configured in NRSE mode, the ground terminal from the EMG amplifier is connected to AISENSE.

I need to get rid of this DC offsetting.
I thought that using a Capacitor connected between the this signal and the input of AT-MIO-64 aichannel will reject this DC component, but this solution is not working!!

Do you guys have any idea what is happening AND ANY RECOMENDATION to AC coupling my system.

Thanks,
Rafael

[RIO-Todd]

Hello Rafael,

I had answered your question via Email but thought I should post it on the developer zone for other users to see.

To AC couple a signal, you could build a highpass RC filter and place the filter in front of the AT-MIO-64E-3 device. This would eliminate the DC component of the signal.

A capacitor in series with a signal should also
AC couple the signal.

I hope this helps and good luck with your project.

Regards,

Todd D.
NI Applications Engineer

[RIO-Todd]

Some additional info: Below you'll find a link that I found that discuss building simple RC
filters. I hope this helps.

Introduction to filters
http://www.csupomona.edu/~apfelzer/209/209-14.pdf