Troubleshooting / Problem Solving

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Revision as of 11:25, 8 November 2013 by Giulio.ruffini (talk | contribs) (Using the testboard)
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Troubleshooting connectivity issues with Bluetooth

Basic Information

The Enobio/StarStim NECBOX connects to the computer using the windows bluetooth stack. It is important to check if the computer has the Windows stack installed and working. This is not obvious when:

The computer is a toshiba Laptop (it might use the Toshiba Stack)
The computer has Windows XP (The stack depends on the dongle used)

If the computer has integrated bluetooth hardware, the system shall be used with their integrated bluetooth. Do not use the provided dongle in a computer that has integrated bluetooth (such as a Mac).

Some known problems and solutions:

After a certain time, the device doesn't connect anymore : remove the bluetooth device from the BT device manager and remove the associated COM ports from the device manager. Let NIC install them again.

With a Windows 8 installation you find it is impossible to connect: contact NE for a new Bluetooth library.

EEG recording issues

If you find noisy signals even after waiting for a few minutes for the electrochemistry to stabilize, check first the DRL/CMS electrode placement. If all electrode signals are noisy you may have a bad DRL/CMS setup. Remove these electrodes, clean the area (mastoid) with a napkin and water/alcohol, and reattach with fresch StickTrodes.

You should also ensure you have a reasonable battery charge (>20%).

If a single channel is at fault, add more gel (unless you are using a DryTrode) and try to establish a good mechanical contact between the electrode and the scalp, removing some hair if you can. If this still does not work, try replacing the electrode using a new (or othewise well-behaved one).

If the problem persists, you may have cabling issue. Try to swap cables across two electrodes (one behaving well, the other bad) to see if the problem follows the cable or the electrode.

If you have a NE Testboard, you can check that the NECBOX is functioning properly by connecting it to the testboard and observing signal quality in all electrodes. If a channel is misbehaving, contact our Technical Support.

Stimulation issues

Problem: the impedance check returns too high impedances.

Note: normally the measured impedances of the impedance check might be higher before stimulation, but when the experiment starts after some time they might fall down. This is normal (stimulation can itself lower impedance).

If impedances are too high you can: - Add more saline solution to the electrodes and check again - Move your hair to avoid as much hair as possible under the electrode - Add some saline solution directly at the hair at the electrode zone - Check that the DRL/CMS electrodes are correctly placed

Impedances depend on skin type, and can vary quite a bit across individuals.

You should also ensure you have a reasonable battery charge (>20%).

Using the testboard

A good tool for debugging is our testboard (contact us if you want one).

This board connects to your NECBOX and allows to test different system functionalities as well as discard problem areas.

You can use your the testboard to record EEG, for example. The testboard is just a bunch of resistors connected so that the impedance seen by any electrode wire is about 5 KOhm (the resistors have a precision of about 5%). Resistors produce (Nyquist) noise as well as pick up noise from the environment (try waiving a magnet near the board, for example).

With a testboard you should see small EEG signals, with an STD of about 1-2 uV in the 1-40 Hz band. If this checks, your device is working properly. If you see larger signals, there may be an issue with your device (contact us).