Hello all, we are exploring our options to buy a data acquisition system and a physiological amplifier for recording ERGs. We want to get a system that can be triggered for acquisition and event marking through Psychtoolbox that will be displaying the ERG stimulus on a screen.
For the project we are working on, timing is really important. We have identified a couple of instruments, but the salespeople are a bit skeptical about the speed and synchronization of the DAQ system with Psychtoolbox.
Does anyone in the forum have any suggestions regarding hardware? We are running psychtoolbox on the latest version of Ubuntu on a high spec/speed computer. We are pretty flexible on the trigger signal as we haven’t settled with any method yet.
I have checked other posts regarding DAQ system, but they are pretty low specs for our project, i.e. not enough resolution (i.e. not 16- or 24bit).
I appreciate any input
Thanasis
A robust system will separate the stimulus generation and data acquisition to two seperate machines, so then to sync these require a “reliable” sync trigger: for visual stimulation with a trigger precision in the order of µs you can use either a DataPixx or a Display++, this is the hardware map as an example (opticka is the PTB machine, DAQ is an omniplex):
It is the display device that generates the trigger itself, so this overcomes the potential for scheduling issues in stimulus system. These systems can generate strobed words, so that they can signal the stimulus value or other data directly, rather than having to deal with aligning data post-hoc. Such systems bring other benefits, such as higher bitrange outputs etc.
BUT, for less time sensitive systems I’ve also used simpler and cheaper USB DAQs like the LabJack controlled by PTB, and they are really reliable and offer close to msec latency. Running test experiments and using a photodiode for ground-truth, I never found any significant scheduling errors in testing. Even more reliable is to use a hardware serial or parallel port if your machine has one…
So for your DAQ system, ideally it should be able to receive strobed words or at least single triggers, and also offer something like an API. For the omniplex, I can communicate via TCP/UDP and then get an online data display during data collection lnked to the variables used by the stimulus computer…
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