Analog/Digital Anti-Aliasing Filters

The design issues of anti-aliasing filters (AAF), which are included in the input circuit of the analog sensor signals, are considered. Analog (AAAF) and digital (DAAF) AAFs provide a aliasing error (γA) at the time sampling of sensor signals in control and monitor systems (CMSs). It is shown that AAAF can't be formed only on the basis of DAAF. This is due to the fact that in CMSs the value γ
_H
is determined to a large extent by the parameters of input AAAF, without which it can not be done. The function of AAAFs can sometimes be discharged by unitizing transducers of sensors or simple additional analog filters of low order. Numerical values are determined in the NI LabVIEW software environment at low orders of the AAAF. It is shown that the efficiency of AAAF is improved with a decrease of the permitted value of γ
_H
. It is established that the calculation of the dynamic error of the analog-digital AAF is complicated by the signal delay, but the order of value of the error remains the same as in AAAF. It is concluded that the separation of filtering between the analog and digital parts of AAAF should be solved as a part of the task of allocation of the error in the input circuits of CMSs.