Pulse or digital communications – Repeaters – Testing
Patent
1990-01-23
1992-08-04
Safourek, Benedict V.
Pulse or digital communications
Repeaters
Testing
375 96, 375 97, 375111, 371 46, H04B 126, H04L 704
Patent
active
051366169
ABSTRACT:
The invention relates to a method and to an arrangement for rapidly controlling the frequency of a radio-receiver which receives signal-sequences which have been subjected to interference and which include a synchronizing-sequence and a data sequence. The signal-sequence is converted in an A/D-converter to provide signal-points (E.sub.T) which are intended for analysis, and a Viterbi-algorithm (10) is adapted (12,13) with the aid of adaption signals (U.sub.1.sup.K) obtained from the synchronizing-sequence of the prevailing interferences. The data-sequence is Viterbi-analyzed through a large number of calculating stages, for the purpose of determining the bit-sequence (S1) of the data-sequence. According to the invention the signal-point (E.sub.T) is branched-up to branch-signal points (E.sub.T), the number of which is equal to the number of states of the Viterbi-algorithm (10). Each individual branch-signal point is phase-shifted (20) to a corrected signal-point (E.sub.T,1) and is compared (21) with its adaptation signal (U.sub.1.sup.K), which has separate (K) signal points. Distances (.DELTA.S.sub.T,1.sup.K) and angular deviations (.DELTA..phi..sub.T,1.sup.K) are calculated between the corrected signal-point (E.sub. T,1) and the adaptation-signal (U.sub.1.sup.K) signal points. A transition (K.sup.1) is selected through the Viterbi-algorithm (10), with the aid of the distances (.DELTA.S.sub.T,1.sup.K) and the angular deviation (.DELTA..phi..sub.T,1.sup.K) corresponding thereto is selected (22). Selected angular deviations (.DELTA..phi..sub.T,1.sup.K) for successive incoming signal-points (E.sub.T) are low-pass filtered and integrated (22) to form a phase correction signal (V) through which the phase of the successively incoming branch-signal points (E.sub.T) are shifted (20). Corresponding phase correction signals are calculated for the remaining states of the Viterbi-algorithm (10).
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Safourek Benedict V.
Telefonaktiebolaget L. M. Ericsson
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