| 摘要 |
A method and an arrangement are described for controlling the frequency of a radio receiver which receives signal sequences subject to interference and which include a synchronizing sequence and a data sequence. A signal sequence is A/D converted to signal points (I,Q) intended for analysis, and a Viterbi algorithm is adapted to the prevailing interference with the aid of the synchronizing sequence. The data sequence is Viterbi analyzed through a large number of calculating stages, for the purpose of determining the bit sequence of the data sequence. According to the invention, a bit sequence is extracted during the Viterbi analysis, with a time delay (TE), subsequent to effecting a few calculating stages, and a corresponding extracted signal point is calculated. The analysis intended signal point corresponding to the extracted signal point is divided and time delayed, and phase compared with the extracted signal point. Corresponding phase comparisons are made with respect to consecutive signal points in the data sequence and the angular magnitudes obtained in the phase comparison are lowpass filtered and integrated to form an angle shift signal. The analysis intended signal points are displaced angularly by the angle shift signal prior to the Viterbi analysis.
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