Black Box IEEE 1284 Uživatelská příručka stáhnout pdf (Strana 27)

The Black Box Toolkit Page 27 of 98

7.3. Adjusting sensor thresholds for optimum performance

Before testing the timing accuracy of any paradigms running on a remote PC it is important

to ensure that any sensors being used have their thresholds set correctly. For example if

making use of the BBTKs digital microphones the trigger level, or “crossing threshold”, of

these will need to be set so that a stimulus sound triggers the appropriate line reliably.

To help ensure that the BBTK has been setup correctly a small utility program can be

installed on the remote PC. Please consult the “software installation” section for details of

how to do this. Also note that currently the “Sensor Check” software will only run on

Microsoft Windows based platforms. Another small utility, “Sensor Threshold Check”, is

automatically installed on BBTK host PCs. This is used alongside the main software to

help aid in final tuning of the opto-detectors and microphones.

Once installed the sensor check software on the remote PC contains features that are

commonly found in paradigms in the behavioural and brain sciences. For example it can

simulate a paradigm that involves simple visual reaction time, cross-modal priming or

complex video based presentations. In short it enables you to simulate running a paradigm

that contains many of the features of your own and enables you to alter sensor positioning

and trigger thresholds quickly and easily.

A screen shot of the sensor check utility running on a remote PC is shown below.

Remember the remote PC is the one which will ultimately be running your own paradigm

to be benchmarked.

7.3.1. Tutorial 1: Setting-up opto-detectors for monitoring visual stimuli

As can be seen from the screen shot there are numerous 32x32 white blocks strategically

positioned around the interface. To begin with you should check that the “Luminance

Sensitivity Threshold” for opto-detector you wish to use is set correctly. Using the fixing

strap position the opto-detector over the lower white block shown on the simulated TFT

display.

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Black Box IEEE 1284 Uživatelská příručka Strana 27