Overview of the standards described in the TOBI project

If you ever had a course on Standardization or did some research by yourself, probably the case of the Great Baltimore Fire rings a bell. The compatibility is always a great challenge when different systems with different requirements and outputs are combined. That is why through standards a great effort is made to increase the interoperability between systems. In order to do so it is often recommended to have standard interfaces that will adapt to different conditions, in different applications.

Unfortunately, I found that the description for each one of these standards is often vague and only one paper appears to be published describing TiA interface. However, short descriptions of each of the standards are available on the websites related to the project. Below you can find the information exactly how it is provided by the partners.

TiA - Data acquisition interface 
"With TiA we attempted to standardize the first interface shown in Mason and Birch's model between "Amplifier" and "Feature Extractor'". BCI as well as neuroscience research in general would benefit from this interface, as the used hardware becomes irrelevant and easily exchangeable as a result of a standardized abstraction layer. With TiA it is possible to reliably transmit data (e.g., for recording) using TCP or use unreliable transmission via UDP if needed based on the users choice. TiA is separated into two parts: (i) a meta information transmission (e.g., channel names, sampling rates) and (ii) the actual data transmission, transmitting the acquired data to the client(s) in an efficient way with minimal overhead also supporting multirate signals and different signal types (e.g. EEG, EOG, EMG, ... ). at the same time."

TiC - BCI output interface
"TiC defines the way classifiers in the BCI transmit their outputs to other modules. Thinking in terms of Mason and Birch’s BCI model, TiC is designed to provide a generic interface between the BCI Transducer and the Control Interface. It is based on XML and the usual way of transmission is network based (TCP/IP or UDP). It requires little setup. Also, TiC supports a hybrid setting, where multiple classifiers may be transmitting at any one time."

TiD - Markers and events interface
"TiD is designed for flexibility, whilst preserving compatibility with legacy implementations. What this means conceptually is that TiD can work in asynchronous mode, allowing the immediate distribution of markers to all modules that have registered to receive them. In the case of a synchronous BCI, as is the case for most current implementation, it simply means that a single module registers for getting the markers."

As it can be seen all three different standards are related to compatibility.  Because we are more interested in the stages behind the standardization than the technical details of each standard, I will stick to this descriptions. However, the following block diagram should provide an idea of where we can find this interfaces in a BCI system.

The figure was extracted from the paper "Tools for brain-computer interaction: a general concept for a hybrid BCI" and all rights belong to the original authors.

If you are interested in more technical details on the subject, a more detailed presentation can be found here.