H - Electricity – 04 – B
Patent
H - Electricity
04
B
325/71
H04B 1/16 (2006.01) H03L 7/087 (2006.01) H04L 27/227 (2006.01) H04L 27/00 (2006.01)
Patent
CA 1304450
PHF 87.573 1 September 1988 ABSTRACT: "Circuit for recovering the carrier of digital transmission systems". A circuit for recovering the carrier of a digitally modulated wave comprising a voltage-controlled oscillator (17) that is controlled by an error signal .epsilon.(.PHI.) in order to adjust the phase of the oscillator, the modulated wave being introduced into two channels, the one in phase (10) and the other in quadrature (20) with the carrier, the two channels being joined together by a phase comparator arrangement (25) which produces the error signal and a sampling clock (H1). The phase comparator arrangement (25) alternately operates as a phase detector and as a frequency detector and therefore comprises means for selecting received signal points with the aid of selection zones formed by ring segments, situated around certain states of the signal constellation. The signals of the in-phase and quadrature channels are used to address a memory (26) that contains the information belonging to or not belonging to the signal point received in one of the selected zones as well as the amplitude and the error sign that relate thereto. In addition, the phase comparator arrangement (25) comprises means (28, 29) for generating the sampling clock (H1) which, in the acquisition mode (off-hook), validates the basic clock H only for these selected zones and, in the permanent mode (on-hook), validates all the edges of the clock H for forming the sampling clock.
578103
Fetherstonhaugh & Co.
N.v. Philips Gloeilampenfabrieken
Sari Hikmet
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