Patent ID: 8817861

Claim:
A complex condition determination unit, comprising: an error-pulse switching determination unit that outputs, as error-pulse determination information, information indicating whether an accumulated value of the number of error pulses accumulated over a predetermined period is equal to or greater than a predetermined error-pulse threshold value, the error pulses indicating whether an error exists in a received signal; CNR (Carrier to Noise Ratio, i.e. carrier-wave power to signal power ratio) modulation scheme determination unit that outputs, as CNR determination information, a modulation scheme determined in accordance with a predetermined CNR threshold value and CNR information indicating a CNR of the received signal; RSL (Received Signal Level) modulation scheme determination unit that outputs, as RSL determination information, a modulation scheme determined in accordance with a predetermined RSL threshold value and RSL information indicating a RSL of the received signal; and complex modulation scheme determination unit that determines the modulation scheme for a transmission source of the received signal, in accordance with the error-pulse determination information, the CNR determination information, the RSL determination information, and received modulation scheme information indicating the modulation scheme of the received signal.