Blind equalisation of multilevel PAM data for nonminimum phase channels via second- and fourth-order cumulants

This paper introduces a new blind equalisation algorithm for the pulse amplitude modulation (PAM) data transmitted through nonminimum phase (NMP) channels. The algorithm itself is based on a noncausal AR model of communication channels and the second- and fourth-order cumulants of the received data series, where only the diagonal slices of cumulants are used. The AR parameters are adjusted at each sample by using a successive over-relaxation (SOR) scheme, a variety of the ordinary LMS scheme, but with a faster convergence rate and a greater robustness to the selection of the ‘step-size’ in iterations. Computer simulations are implemented for both linear time-invariant (LTI) and linear time-variant (LTV) NMP channels, and the results show that the algorithm proposed in this paper has a fast convergence rate and a potential capability to track the LTV NMP channels.

Virgil's fourth Eclogue and the visual arts

Virgil's poetry has frequently appeared in illustrated editions, and has regularly provided subjects for other works of art, including some of the most celebrated masterpieces of the western tradition. In view of its constant appropriation in literary contexts over the course of the centuries, we might expect the famous fourth Eclogue (the so-called ‘messianic’ eclogue) to have exerted more of an impact on visual culture than it appears to have done. This paper considers some of the possible reasons for the apparent scarcity of engagement with Virgil's poem beyond the literary sphere, and examines the uses to which the poet's text is put when it does make an appearance in visual media — perhaps more often than has sometimes been supposed.