ADAPTIVE EQUALISER IMPROVEMENTS FOR 16 QAM AND 64 QAM DIGITAL RADIO

摘要

The performance of transversal and decision feedback equalisers is compared for multipath fading effects on 16 QAM and 64 QAM digital radio systems. The effect of tap spacing is examined by comparing results of baud period spacing with fractionally spaced equalisers.Results indicate that for minimum phase fades a decision feedback equaliser with fractional spacing on the feedforward part offers the best performance. During non minimum phase fades, to best utilise the presence of feedback taps, a modified timing recovery scheme is proposed by means of which a NMP fade is seen by the equaliser as a psuedo MP condition. The performance of the receiver during MP fades with the modified timing remains uncompromised.