A method for acquiring electrical signals from aliving subject, including injecting, via an injectionelectrode attached to the subject, a known calibrationsignal to the subject and measuring respective levels ofoutput signals generated at input electrodes attached tothe subject in response to the calibration signal. Themethod further includes deriving respective weightingfactors for the input electrodes in response to therespective levels, and applying the respective weightingfactors to physiological signals acquired by the inputelectrodes, so as to generate respective correctedphysiological signals.
