LiveAmp with Sensor & Trigger Extension for GSR signal recording
The LiveAmp is an ultra-lightweight, wearable amplifier that can record referential EEG Electroencep- halography channels and bipolar channels. BP Brain Products GmbH sensors can be used with the LiveAmp in combination with the Sensor & Trigger extension, providing 8 AUX Auxiliary channels ( Figure 8 ).
LiveAmp - Sensor and Trigger extension AUX ports technical specifications
The Brain Products sensors can be used with the LiveAmp in combination with the Sensor & Trigger extension, providing 8 AUX channels ( Figure 8 ). The sensors connected to the AUX ports receive power supply from the the Sensor & Trigger extension’s dedicated battery. The pin-out of the AUX ports and additional technical data are indicated in Figure 7 and Table 2 .
Figure 7 Pin-out (View from the top) of the AUX ports of the Sensor and trigger extension for LiveAmp.
Pin No. | Function |
---|---|
1 |
+5 V DC |
2 |
+Signal |
3 |
Ground |
4 |
-Signal |
5 |
-5 V DC |
Table 2 Technical data of the AUX ports in the Sensor and trigger extension for LiveAmp.
Number of AUX channels |
8 |
Input voltage range |
± 4.8 V |
Max. current for all AUX channels together |
80 mA (either 1x80 mA or 8x10 mA) |
Amplitude resolution |
1.07288 µV/bit. |
Max. Bandwidth |
SR = 1000 Hz: 262 Hz SR = 500 Hz: 131 Hz SR = 250 Hz: 65 Hz |
Figure 8 LiveAmp and LiveAmp Sensor & Trigger extension. The GSR module is connected to one of the AUX ports of the Sensor & Trigger extension.
The BrainVision Recorder workspace should be set as in Figure 9 for GSR Galvanic Skin Response recordings, given the following considerations.
The lowest available sampling rate is sufficient to record the GSR signal. However, the sampling rate set in the workspace applies to all recorded signals. If GSR is recorded simultaneously with other signals, e.g. EEG, a higher sampling rate may be required depending on the specific application. If needed, downsampling can be easily applied to the GSR signal offline.
The correct physical channel number must be indicated in the column “Phys. Chn” of the channel table ins the workspace. The AUX channels always correspond to the last 8 physical channels, therefore in the BrainVision Recorder workspace settings, if you have a LiveAmp 32, the AUX channels will correspond to physical channels 33-40, if you have LiveAmp 64, the AUX ports will be physical channels 65-72 ( Figure 9 ).
In order to set the correct units, gradient and offset in the channel table, check the box “Diff. Unit”, write “µS” as “Unit”, 25 as “Gradient” and 0 as “Offset”.
The other settings are dependent on your individual experimental requirements. For additional information about setting up a BrainVision Recorder workspace, please refer to the Recorder user manual.
Figure 9 BrainVision Recorder workspace settings for recording GSR with LiveAmp: in the channel table check the box “Diff. Unit”, write “µS” as “Unit”, 25 as “Gradient” and 0 as “Offset”. The other settings are dependent on the individual experimental requirements.