Patent ID: 11870489
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Telecommunications (Electrical engineering)
Classification: CPC H | IPC H

Claim 3:
4. An adaptive filter circuit, comprising:
a filter unit that filters a received signal on the basis of a filter coefficient;
a tentative decision unit that makes a tentative decision for symbols on the basis of the received signal that has been filtered and a decision threshold, and outputs a tentative decision signal including a sequence of the symbols;
an updating unit that updates a scale value indicating a rate of increase or reduction of the received signal that has been filtered or updates a threshold change rate indicating a degree of change in the decision threshold so that an appearance frequency of each of the symbols included in the tentative decision signal output by the tentative decision unit matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission, the modulation method being shared between a transmitting side and a receiving side; and
a filter coefficient updating unit that, on the basis of the received signal, the received signal that has been filtered, and the tentative decision signal output by the tentative decision unit, calculates an update value for the filter coefficient, and provides the update value for the filter coefficient that has been calculated to the filter unit,
wherein when the scale value is updated by the updating unit, the tentative decision unit makes a tentative decision for the symbols on the basis of the received signal that has been filtered and has been increased or reduced by the scale value that has been updated, and the decision threshold, and when the threshold change rate has been updated by the updating unit, the tentative decision unit makes a tentative decision for the symbols on the basis of the received signal that has been filtered and the decision threshold to which the threshold change rate that has been updated is applied.