Documentation of nrec Parameters

1. Data Acquisition

•  sampling rate 

  • Acquired samples per second by the daq card.

•  SubdeviceID for AIn eye position recording (16ch) 

  • The ID of the analog input subdevice (find out via comedi_test -t info).

•  SubdeviceID for DIn spike recording (24ch) 

  • The ID of the digital input subdevice (find out via comedi_test -t info). If no spikes or comparable digital signals are to be recorded, set this value to -1.

•  SubdeviceID for other DIO (8ch) 

  • The ID of the digital in-/output subdevice (find out via comedi_test -t info). The trial trigger is on channel 0 output. The other channels may be used for response buttons, reward signals, LEDs and similar things.

2. Experiment file

•  Experiment file 

  • Path and filename of the last experiment configuration used. Usually this is not modified here.

3. Eye position module

3.1. Calibration

•  Channel 0 

  • Currently used horizontal calibration coefficients. These are the 6 coefficients a,b,c,d,e,f in the voltage (x) to gaze_angle funtion:
    ganze_angle = a + b * x + c * y + d * x² + e * x * y + f * y².
    Usually this is not modified here.

•  Channel 1 

  • Currently used vertical calibration coefficients. These are the 6 coefficients a,b,c,d,e,f in the voltage (x) to gaze_angle funtion:
    ganze_angle = a + b * x + c * y + d * x² + e * x * y + f * y².
    Usually this is not modified here.

•  # Channels 

  • Number of channels used for eye position calibration. Use 1 for x-only mode or 2 for x-y-mode.

•  # Coefficient/channel 

  • Number of calibration coefficients per channel. Order of the polynomial in the above equations. Currently only a value of 6 is implemented.

3.2. Input hardware

•  # Channels 

  • Number of channels used for eye position measurement. Currently only a value of 2 is implemented.
    Usually this is not modified here.

•  Device ID 

  • Device ID for eye movement data acquisition. Usually 0.

•  Subevice ID  

  • Subdevice ID for eye movement data acquisition. Usually equals DAQ/SUBDEVICE_ID_AIN.

•  X Channel ID 

  • ID of channel for horizontal eye position. Usually 0.

•  Y Channel ID 

  • ID of channel for vertical eye position. Usually 1.

4. Local system setup

4.1. Monitor

•  Distance 

  • Viewing distance between eyes and screen in mm.

•  Frame rate 

  • Refresh rate of the screen.

•  Height 

  • Height of the screen in mm.

•  Width 

  • Width of the screen in mm.

4.1.1. Resolution

•  Horizontal 

  • Number of horizontal pixels (columns).

•  Vertical 

  • Number of vertical pixels (rows).

4.2. Stimuli

•  Clear Screen at the End of Experiment 

  • If activated, the screen is cleared when the experiment is finished or stopped.

•  Frameerror handling 

  • 0: strict, system assumes that calculation of a new frame lasts less than 1/framerate seconds.
    1: tolerant, system allows the frame calculation to be longer than 1/framerate seconds. Especially useful in conjunction with movie primitives.

•  Minimum trial duration 

  • Use this parameter, if you want to ensure, that the time between the start of two consecutive trials is constant. Deactivated, if set to -1.

4.3. Stimulus window

Parameters defining the graphics output. You will have to restart nrec to apply these settings.

*  Full screen 

• If activated, the whole screen is used instead of a window.

*  Graphics system 

• DirectFB is obsolete. Use "X Window".

•  Height 

  • Number of vertical pixels (rows).

•  Width 

  • Number of horizontal pixels (columns).

•  X Display Name 

  • Choose the appropriate X Display. For Notebooks e.g., the external screen normally is :0.1
    Caution: If the chosen display is not GLX capable, nrec might not start up anymore. You will then have to edit .nrec.cfg manually or using a XML-editor and set this parameter back to a valid value.

... to be continued