subsection_Multifrequency_The_stability_of__.tex

\subsection{Multifrequency}
The stability of the system across frequency previously demonstrated in the resistor phantom experiments was also present in recordings in stroke patients, as SNR did not demonstrate a significant frequency dependence. However, overall the SNR did decrease compared to recordings in subjects at rest in section \ref{scalp}, which were largely a result of a greater prevalence of motion artefacts from patient movement. The stability over frequency and increased electrode movement were further demonstrated in the drifts over the 25 minute recordings, which were similar for all three frequencies. Whilst the imaging in these applications is still the subject of research \cite{malone2015} \cite{jang2015detection}, the datasets collected with this system constitute the most comprehensive recorded, and form a basis for future research.