reception facility with demoduleringsfunktion based on ortogonal detection and utju00e4mningsfunktion based on estimation of maximum sannolikhetssekvens

摘要

In a receiving device, a mixer combines a frequency which is different from a carrier frequency by (2n+½)omega0 and a reception signal, provided that n is an integer, omega0=2PI/T, and T is a transmission rate of a base band signal, a filter takes out a base band signal of a center frequency of (2n+½)omega0 and removes a DC component, so as to sample the signal and put it through A/D conversion, a multiplier combines the signal and a polarity signal, so as to obtain an in-phase component p(nT) of the reception signal at time nT and an orthogonal component q[(n+½)T] of the reception signal at time (n+½)T. A branch metric is calculated and maximum likelihood sequence estimation is executed on the basis of those components and a replica signals pR(nT) and qR[(n+½)T], so as to estimate a signal sequence. Thus the receiving device exhibits improved performance as it is capable of eliminating any phase difference and amplitude difference between Ich and Qch and any DC offset, without requiring any large-scale additional circuit.