| 摘要 |
PROBLEM TO BE SOLVED: To provide a reliable device and method for detecting information.SOLUTION: The information detector includes a high-pass filter section that is composed to freely change a time constant and extracts a high-frequency component of a communication signal, a squelch detection section for detecting a part where a signal level in the high-frequency component of the communication signal exceeds a preset threshold for squelch detection, an information detection section for detecting information superimposed on the communication signal based on detection output of the squelch detection section, a DC variation detection section for detecting a variation in levels of DC components of the communication signal, a control section for controlling the high-pass filter section to reduce the time constant of the high-pass filter section for a fixed interval when the DC variation detection section detects the variation in levels of the DC component of the communication signal, and a mask section for masking a detection output of the squelch detection section so that the squelch detection section does not detect a part exceeding the threshold for squelch detection while the control section has reduced the time constant of the high-pass filter section. |
