Abstract: When a data signal of a first channel is an RZ signal having a pulse period T1 and a logic “1” pulse width m, a data signal of a second channel is an RZ signal having a pulse period T2 and a logic “1” pulse width n and the relation n<m is satisfied, a multiplexed signal D obtained by time-division multiplexing the data signals of two channels is input. A pulse signal with a pulse width k satisfying n<k<min(m, T2) is generated at timing of a leading edge of the data signal of each channel. When the multiplexed signal D is judged as logic “1” at timing of a trailing edge of the pulse signal, the data signal of the first channel is output. Similarly, when the multiplexed signal D is judged as logic “O”, the data signal of the second channel is output.

Abstract: A receiving section of an infrared receiver includes an error detecting section that detects, through an integrating circuit, a direct-current component of a 1-bit data sequence that is supplied in a form of a PDM signal. The direct-current component thus detected is compared with a reference voltage by the comparing circuit to determine whether the direct-current component is greater or smaller than the reference voltage, and a signal is outputted on the basis of a result of the comparison. When the direct-current component is decreased, it is determined that a bit error rate is greater. At this time, an output of sound from the infrared receiver is caused to become OFF.