BSL PRO 4 Manual - Biopac

Part C — Analysis Functions 243Adaptive Filtering See the Adaptive Filtering CalculationChannel on page 143.Adaptive filtering is a signal processing technique thatprocesses two different signals in relation to one anotherand can be used for noise estimation, noise reduction,general-purpose filtering, and signal separation. Adaptivefiltering creates efficient high-quality filters with a minimalnumber of terms, which can be very useful in blockingmains interferences or other known periodic disturbances.• Useful for noise filtering where it is possible to acquirea signal that is correlated to the noise (similar to theway noise-cancelling headphones detect and removeoutside noise). Applications include removing EMGfrom ECG or EOG from EEG.The weights within an adaptive filter are modified on a step-by-step basis. BSL PRO uses the N-tap FIRadaptive filter, with coefficients updated using least means squares (gradient) feedback.Source signalThe source channel will be replaced by the adaptive filter results.Noise signalThe noise channel is the signal that is correlated with the noise to be eliminated from the Source; it isnot modified by adaptive filtering.Source and Noise channels must have the same sampling rate.OrderSpecify a positive integer for the number of terms to be used in the internal FIR filter.Step sizeProvides mu, the rate of adaptation of the coefficients within the FIR filter.Comb Band Stop FilterComb Band Stop filters out a fundamental frequency and its overharmonics (integer multiples of the base).Resonance, aliasing, and other effects may generate interference at multiples of a base frequency. The CombBand Stop filter combines all the required filters instead of requiring a separate filter for each interferingoverharmonic.Transformation DialogCalculation Channel DialogBSL PRO Manual