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Currently, we're trying to carry out electrophysiological recordings from the mouse brain using Open Ephys acquisition box and a silicon probe, and we are suffering from severe noise in probe signals.

This page in Open Ephys documentation says:

Line Noise caused by USB ground

Sometimes, the USB cable that connects the acquisition board to the PC (which is grounded to the building ground via the power supply) isn't good enough - grounding the external shield of the USB cable that connects the FPGA to the computer can help.

We really wonder how to ground the external shield of the USB cable (we know which USB cable he is talking about). We tried to find answers on the Internet, but could not find one. Could someone elaborate this further, so we can actually make some actions?

SamGibson
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Kouichi C. Nakamura
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    I love this part of the cited documentation: "**Avoiding ground loops**: _add info here_". Sounds easy to me :). But yes, this is a common source of conducted noise. Check into this. – Chris Knudsen Nov 01 '19 at 14:54
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    related (if not duplicate): [How to connect USB Connector shield?](https://electronics.stackexchange.com/q/4515/7036) and [Portable device shielding & ESD](https://electronics.stackexchange.com/a/167555/7036) – Nick Alexeev Nov 01 '19 at 15:02

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Test to make sure the outer shell of the cable connects to the USB connector it plugs in to with a multimeter. If so, then test and see if that is connected to Gnd on the board it is installed on, or to the case of the PC. If so, try making a better connection from the PC case to local Gnd.

CrossRoads
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