| 摘要 |
PURPOSE: A method and an apparatus for determining a signal in a digital signal receiving system are provided to improve the complexity and the resolution of an analog/digital converter by selectively performing a soft decision on a receiving signal of an ambiguous region. CONSTITUTION: A hard decision unit(51) compares a baseband signal generated based on a signal received through a transmitting channel with each of predetermined reference voltages(VTH1,VTH2,,,VTH(L-1)) and performs a hard decision to output decoded data. An ambiguous signal detecting unit(52) receives the baseband signal, reference voltages, predetermined voltages(Vd1,Vd2,...,Vdi) of an ambiguous region, and hard decision data to determine whether or not the received signal is located within a predetermined decision of the ambiguous region and to output the determined result as a signal. A subtraction unit(53) receives the baseband signal, hard decision result data, and the predetermined voltages(Vd1,Vd2,...,Vdi)to calculate a difference voltage between the baseband signal and the predetermined voltages(Vd1,Vd2,...,Vdi). A switching unit(54) selects an output of the subtraction unit(53) to output it if the received signal is in the ambiguous region. Otherwise, the switching unit(54) selects a reference potential to output it. A soft decision unit(55) receives an output of the switching unit(54) and performs a soft decision to output soft decision data.
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