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Training on Data for a Two-Phase DPSK Modem

IP.com Disclosure Number: IPCOM000057895D
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15

Publishing Venue

IBM

Related People

Authors:
Maddens, F Mauduit, D [+details]

Abstract

Training on data is the way by which a modem recovers from line drops, or initializes its receiver after power-on. In all these cases, the modem has to retrieve the coefficients of the adaptive equalizer which compensates for the amplitude and phase distortion introduced by the telephone channel. With a two-phase DPSK modem, the two-phase signal contains no quadrature component. The effect of amplitude and delay distorsion is to introduce such a component. This undesirable component may be amplified by the adaptive equalizer which, at the initialization, may converge into a stable state, exhibiting, for example, a four-phase received signal instead of the two expected phases.