In this focus group signal processing related aspects are bundled to minimize redundancy among the projects and allow for common research on overlapping topics. Such topics start with very basic preprocessing steps such as offset removal (high pass filtering) for the recorded ME signals. Several of the medical projects need 3-dB cut-off frequencies of about 0.1 to 1 Hz at sample rates of 100 kHz and more. This results in sophisticated filter structures even for hardware components with 32-bit floating-point precision. The same is true for notch filters (removal of 50 Hz distortions and multitudes of this basis frequency). Furthermore, the removal of artifacts and noise, either in terms of temporal exclusion or attenuation as well as subtraction (using adaptive filters), is necessary in a variety of B projects. The same is true for multi-channel localization approaches such as beamforming or correlation-based approaches. After such preprocessing steps, a multitude of signal analyses, either of single ME signals or of a whole set of simultaneously recorded ME signals, are performed. This includes, for example, coherence estimations with electrical counterparts of the ME signals or visualization of the data in different domains (time-domain analyses, frequency-domain conversion with different resolutions, mixed-time-frequency-plots, short-term auto- and cross-correlation analyses, inverse solutions, Kalman filtering, beamformer techniques, to name just a few).
The participating projects are B2, B3, B5, B6, B7 and Z2. The activities of the focus group are coordinated by Gerhard Schmidt. During the meetings, current measurement and research results are presented. Data are shared among the projects and the strengths of the data analysis competence in the different projects are capitalized on. The focus group is the place to exchange data, new ideas on data analysis and results. Furthermore, signal analyses that are important for more than one project will be presented and reference implementation are generated using, for example, the simulation tool Matlab.