Adaptive filter method for deriving digital IF filters

For many modulation schemes it can be difficult to derive an IF filter which is best suited for all symbols. In particular, any tailoring of the symbol shaping, additional receiver out of band rejection, or difficult analytical solutions can lead to digital IF filters that produce sub-optimal performance. For these instances, an alternative solution for IF filter design methodology is proposed. Digital IF filters can be created in simulation using common adaptive filtering techniques. In a single step, the tap values for a digital IF filter with specified adjacent channel rejection can be generated. This paper verifies the adaptive filter method for deriving digital IF filters using a non-constant envelope 8-ary phase shift keying modulation and a constant envelope 8-ary continuous phase modulated waveform.