Method and device for detecting figure infra-acoustic frequency signals

Abstract

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.

Description

technical field [0001] The invention relates to the field of walkie-talkies, in particular to a method and device for detecting digital sub-audio signals. Background technique [0002] In the process of using the walkie-talkie to transmit audio signals, in order to avoid mutual interference between different users, a coded identification signaling technology that adds a signal with a frequency lower than the audio frequency to the audio signal and transmits it together is called sub-audio technology. The frequency of the additional signal is lower than the audio frequency, which is called sub-audio signal. The transmitter transmits the modulated audio signal and the sub-audio signal at the same time; the receiver demodulates the received signal, and then detects whether there is a sub-audio signal. If a sub-audio signal is detected, the squelch circuit is turned on and the audio signal is output. Sound through the speaker. [0003] Sub-audio technology is divided into two ...

AI Technical Summary

Problems solved by technology

[0012] use figure 2 When the method shown detects the digital sub-audio signal, Gray decoding is performed, which requires a large amount of calculation; in addition, if the signal is inverted and the polarity of the transmitter and receiver signals are opposite, then the digital sub-audio signal will not be detected. Therefore, the squelch circuit cannot be opened normally

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