Files & Formats

Neuroelectrics devices generate a series of files:

- The ".easy" data format (ASCII) 
- The ".info" file (ASCII)
- The ".edf" (EFF+) and ".nedf" data formats (binary)
- The ".stim" file (ASCII)
- SD card data formats

Stimulation generated files

Neuroelectrics stimulation StarStim class devices generate stimulation specific files as well as EEG data. Here we describe the former (for EEG see the EEG data section).

the .stim file

This ASCII file contains a record of the currents at each electrode. There is a row per time sample. The last column contains the time stamp.

the .info file associated with a stimulation session

Here is an example of the ASCII data file associated to a stimulation session. The name of the file would be something like 20130220112635_Patient01.stim:

StartDate (first EEG timestamp): 1361377909087 
Device class: StarStim
Device Mac: 00:07:80:58:9C:1A
NIC version: v1.1.9
Firmware version: 699
Line filter status: OFF
Additional channel status:OFF
Number of records of Stimulation: 46 (1 second/record)
Total number of channels: 8
Number of EEG channels: 6
Number of stimulation channels: 1
Stimulation sampling rate: 500 Samples/second
Stimulation units: uA
Ramp up duration (s): 15
Ramp down duration (s): 15
Shamp ramp duration (s): OFF
Stimulation duration (s): 1200
Type of stimulation: tACS+
Stimulation parameters:
Channel 1: 
 Position: C3
 Type: EEG Recording
 Channel 2: 
 Position: C4
 Type: Stimulation Anodal
 Amplitude (uA): 100
 Offset (uA): 0
 Frequency (Hz): 10
 Channel 3: 
 Position: Ch3
 Type: EEG Recording
Channel 4: 
 Position: Ch4
 Type: Return
 Percentage return: 100%
Channel 5: 
 Position: Ch5
 Type: EEG Recording
 Channel 6: 
 Position: Ch6
 Type: EEG Recording
Channel 7: 
 Position: Ch7
 Type: EEG Recording
 Channel 8: 
 Position: Ch8
 Type: EEG Recording
Trigger information:
 Code	Description
 1	Subject moved
 2	Eyes opened
 3	Eyes closed
 4	sleeping
 5	EEG signals are noisy
 6	
 7	
 8	
 9

EEG data files and formats

The .easy data format (ASCII)

 ABOUT THE NE ASCII DATA FORMAT (July 2012): 
       NE ASCII files contain one line per time sample. Each line contains
       first the EEG data (8 or 20 channels, depending on the device, with
       units in nV), followed by  three acceleration channels (aX,aY,aZ 
       in mm/s^2- millimeters per second squared), an *optional* external 
       input channel, a trigger flag (int32) and, finally, 
       a timestamp in Unix time (ms from Jan 1 1970):

 Ch1(nV) ... Ch8or20(nV) aX(mg) aY(mg) aZ(mg) AddSensor Flags(uint32) TimeStamp (ms)
   
 Therefore Enobio8/StarStim will have a minimum of 8+2 (10) columns, or 8+3=11 if no 
   accelerometer or >= 8+4 (with accelerometer). In summary:

   Enobio8/20
        10 Columns: no AddSensor, no accelerometer data:
        11 Comumns: no accelerometer, but there is AddSensor
        13 Columns: there is accelerometer, but no Addsensor
        14 Comumns: there is accelerometer, AddSensor.

   Enobio 20 will have >= 22 and >=24 columns if acc. data present:
        22 Columns: no AddSensor, no accelerometer
        23 Comumns: no accelerometer, but there is AddSensor
        25 Columns: there is accelerometer, no AddSensor 
        26 Comumns: there is accelerometer, AddSensor.

   Enobio 32 will have >=34 adn >=36 if acc data is present
        34 Columns: no AddSensor, no accelerometer
        35 Comumns: no accelerometer, but there is AddSensor
        37 Columns: there is accelerometer, no AddSensor 
        38 Comumns: there is accelerometer, AddSensor.

The .edf (binary, EDF+) data format

This is the standard | EDF data format. Files in this format can be opened from EDF data readers.

The .nedf (binary) data format

This is Neuroelectrics proprietary data format. It is lossless (full 24 bit) binary. It can be opened by NIC Offline.