Method and device for detecting figure infra-acoustic frequency signals

The invention discloses a method and a device for detecting figure infra-acoustic frequency signals. The method comprises: A. signals in an infra-acoustic frequency segment can be acquired form received signals; B. the signals in the infra-acoustic frequency segment can be in hard decision to obtain an objective sequence; C. the obtained objective sequence and a preinstalled figure infra-acoustic frequency sequence can be compared; D. when the objective sequence and the preinstalled figure infra-acoustic frequency sequence are identical and different in digits to satisfy a setting scope, the figure infra-acoustic frequency signals are ensured to be detected. In a detective process, the setting scope is used and a gray coding process can be omitted so as to effectively reduce calculated amount and simply the detective process. Furthermore, polarity of signals of a sending side and a receiving side can be taken into consideration. Therefore, the method and the device for detecting figure infra-acoustic frequency signals can be applied to rapidly and accurately to detect the figure infra-acoustic frequency signals so that a squelch circuit can be normally guaranteed to be opened and closed.