Hi Guys,

I was wondering if someone would direct me toward resources regarding filtering high frequencies vs shielding a cable so that it doesnt act as an antenna in a high magnetic field environment. I am trying to figure out a way to eliminate noisy signals to be transmitted through a cable either by filtering it or shielding it, so that our images from the MRI don't have noise spikes in them. Any leads would be greatly appreciated.

V

 

There's always triax - http://en.wikipedia.org/wiki/Triaxial_cable

Ground the outer shield and drive the inner with the buffered signal - http://www.analog.com/static/imported-files/.../41727248AN_347.pdf

 

Ferrite beads or loop the cable a few times round a ferrite ring?

Gate stopper resistors?

Encode the signal to fibre optic and decode at the other end?

 

@beenthere

The issue we are facing is with a specific cable that is connected to a signal processing box and that is connected to the computer. It is an ECG cable to read the ECG of the patient on the computer. And with respect to grounding tthe outer shield, there is no shield. Even if we shield it until the end that connected to the ECG acquisition device on the patient, we disconnect it during imaging that makes it act as an antenna. Please see picture for more.


@studiot

there already is a ferrite bead on the cable just beneath the plug. And looping through a ferrite ring is not possible as we just have so much length of the cable for our purpose.

Gate stopping resistors? what are those?

Encoding would work but this is a commerically available product and until I would know what signals transfer through the cable, I wouldnt be able to encode and decode in the form of light.

Thanks!

V

 

Try using one or more snap-on ferrite noise suppressors close to the usb signal processor.

sth like this ... http://www.farnell.com/datasheets/26127.pdf
If you're in India you can order from in.farnell.com