eego amplifier EE-21x EE-22x User Manual
Rev. 5, DRN-PDO-1664 14 of 26 2016-07-11
Regardless of referential or bipolar recordings the amplified data stream of input signals is converted
from analog (continuous in amplitude and time) to digital (discrete in amplitude and time). Both
dimensions – voltage and time – are digitized in a way that the analog waveforms can be
approximated without loss of quality in further review and analysis steps. The minimum step width is
in the order of (less than) ms (milliseconds) and a few nV (nano Volts), depending on the selected
sampling rate, signal range and resolution (see eego amplifier datasheet). Each signal is treated by its
own converter, so that no multiplexing effects occur.
The digital data stream is then converted into a protocol suitable for computer communication
(USB). Communication between computer and amplifier works in two ways: control commands sent
by the application software make sure that the amplifier takes the requested actions, and the
amplifier sends EEG data, trigger and status information in the respective operation mode.
The application software sets up communication with USB 2.0 (USB 3.0 is fully compatible with USB
2.0 standard) and provides user interfaces to display and record the measurements.
2.3 RECORDING TRIGGER INPUT
In case you want to record event-related activity, we assume you have available a PC with
presentation software, which is able to deliver TTL pulses along a parallel port cable (DSUB 25 pin
connector, male) with pinning compatible with the description in Appendix A.
WARNING: Make sure that the computer generating the trigger signals is compliant with
IEC 60950.
To run an ERP experiment, please insert the trigger adapter XS-230 into the high-density trigger input
of the amplifier. The DSUB connector at the other end of the adapter is connected with a parallel
port cable that links with the DB25 port of the presentation PC (cable, presentation PC and software
not provided with the eego amplifier).
The 8-bit trigger information is encoded in a decimal trigger code (from 1 to 255) in the recording
software.
Please be aware that only rising flanks are detected as triggers and as high trigger bits! A trigger
pulse should have a length of at least 2-3 times the reciprocal of the sampling rate. In between
triggers the Low level must also be hold for 2-3 times the reciprocal of the sampling rate.
2.4 MOUNTING OPTIONS FOR THE EEGO AMPLIFIER
The eego amplifier can be used as a stationary device or as a mobile device.
When using eego amplifier as a stationary device, please make absolutely sure that the amplifier
cannot drop from the table, e.g. when the patient is connected with the cap and tries to walk away
or when the USB cable is dragged over the table sides. You can for example put a string through the
mounting holes to fixate the amplifier box.
In mobile EEG applications, we strongly recommend to mechanically protect the amplifier with the
eego amplifier soft-shell. Do not remove the soft-shell from the amplifier.
To Next Page
Loading...
