| 摘要 |
PROBLEM TO BE SOLVED: To perform sampling at a frequency lower than a carrier frequency. SOLUTION: An infrared communication signal converted into an electric signal is inputted to a data sampling circuit 1 and only a signal of a band below a frequency of a carrier signal is extracted by an LPF 1a. When the communication signal is inputted from the LPF 1a, a detection information holding unit 1b sets detection information indicating that the communication signal is detected, and holds the information for a predetermined time. When a sampling period comes, a communication signal detection unit 1c is driven and the detection information held by the detection information holding unit 1b is stored in a storage means. The detection information, stored in the storage means, in the last or more previous sampling period is then compared with the detection information in the present sampling period to determine whether the communication signal is inputted or not. On the basis of a measurement result, a measuring unit 1d measures a term during which communication signals are continuously inputted, or a term during which no communication signal is inputted. COPYRIGHT: (C)2008,JPO&INPIT
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