User manual

Appendix A: Using the EyeLink 1000 Analog and Digital Output Card

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Gaze: This is actual gaze position on the display screen. A calibration

must be performed to obtain this measure.

The EyeLink 1000 system offers integrated data recording and digital data

transfer methods, which do not suffer from the timebase, resolution, and noise

degradation inherent in analog systems.

7.2 Analog Data Quality

The EyeLink 1000 analog output system is intended for use with commercial

data-collection systems such as LabView, or for backwards compatibility with

existing eye-tracking software and systems. However, analog data transfer may

significantly degrade data quality compared to recording to file or digital

transfer via the link. Typically, at least 1 or 2 bits of noise are added by the

analog output, cabling, and re-digitization of analog signal transfer. The typical

EyeLink noise level is 0.01 degree RMS: analog data transfer can increase the

noise level by a factor of 2 to 20.

The EyeLink 1000 system offers integrated data recording to file, and digital

data transfer through the Ethernet link, which has latency comparable to the

analog link and does not suffer from the time base, resolution, and noise

degradation inherent in analog systems. SR Research Ltd. is committed to

improving access to the Ethernet link data transfer methods, and supplies an

analog output option for backwards compatibility with existing experimental

systems and as requested by users, but does not encourage its use in new

systems.

7.3 Setting up the EyeLink 1000 Analog Card

7.3.1 Installing Analog Output Hardware

The EyeLink 1000 frame grabber PCI card and DLINK Ethernet card should be

installed before the analog card can be accessed.

To install the analog output card, open the case of EyeLink Host PC, install the

card into an empty PCI slot, and secure the rear bracket of the card with the

bracket screw or card clamp (depending on your computer model). The EyeLink

1000 tracker software will automatically find and use the analog card.