Abstract: An electrode cap for obtaining EPM signals from a head of a subject, the cap comprising: (i) an insulating layer (33) for positioning adjacent to the head of the subject; (ii) an electrically conductive layer (29) comprising ionic conduction means, situated above the insulating layer so that in use, it is separated from the head of the subject by the insulating layer; (iii) a plurality of measurement signal electrodes (13) extending through the electrically conductive layer and the insulating layer for contacting the head of the subject, the measurement signal electrodes being electrically insulated from the electrically conductive layer; and (iv) at least one reference node (53, 55) electrically connected to the electrically conductive layer.

Abstract: An electrode cap for obtaining EPM signals from a head of a subject, the cap comprising: (i) an insulating layer (33) for positioning adjacent to the head of the subject; (ii) an electrically conductive layer (29) comprising ionic conduction means, situated above the insulating layer so that in use, it is separated from the head of the subject by the insulating layer; (iii) a plurality of measurement signal electrodes (13) extending through the electrically conductive layer and the insulating layer for contacting the head of the subject, the measurement signal electrodes being electrically insulated from the electrically conductive layer; and (iv) at least one reference node (53, 55) electrically connected to the electrically conductive layer.

Abstract: In an electronic circuit and method for reducing interference in a measurement signal or signals, wherein the interference comprises a plurality of interference components: (a) There is at least one primary signal processing unit, each having a primary signal processing unit comprising a respective measurement signal input for receiving a respective one of said measurement signal or signals. The or each primary signal processing unit comprises a plurality of interference reduction modules. (b) A respective compensation signal component input is provided for each interference reduction module. (c) A compensation signal processing unit is provided, having a compensation signal input and comprising means for deriving from at least one compensation signal, a plurality of compensation signal components each of which is related to a respective one or more of the interference components.

Abstract: An electronic apparatus for reducing interference in a desired signal, the apparatus comprising: (a) a plurality of measurement signal lines, each connected to a respective measurement signal electrode; and (b) one or more reference signal lines, each connected to respective one or more reference electrodes; each of said measurement signal lines or a respective group of said measurement signal lines being associated by being in close physical proximity with a respective one of said reference signal lines for a substantial part of their lengths, so that each measurement signal line or signal line group with its corresponding reference signal line forms a measurement signal line or measurement signal line group/reference signal line pair, said electronic apparatus further comprising subtraction means for subtracting an interference on each reference signal line from an interference signal on the associated measurement signal line or from each measurement signal line in the measurement signal line group in that