An anti-interference acoustic detection method for cross-water-air medium communication

In cross-water-air medium communication using laser detection for signal reception, the detection signal is susceptible to external noise interference, leading to a degradation in communication quality. This paper proposes an anti-interference acoustic detection scheme for laser detection equipment. The scheme first transforms the traditional underwater MFSK (Multi Frequency Shift Keying) modulation method into M-LFM (Multi-Linear Frequency Modulated) modulation, encoding information into the slope information of the LFM signal. Subsequently, at the laser detection equipment signal reception end in the air, the received signal is preprocessed using optimal fractional Fourier transform to eliminate abnormal impulse noise and then inverse transformed into the time domain. Finally, the preprocessed signal is matched with the modulated baseband M-LFM signal to complete information demodulation. The simulation results show that the communication scheme in this paper can ensure the correct decoding of the signal under the external high-intensity and wide-band ambient noise interference, and at the same time, the effectiveness of the scheme is verified through the pool test, which confirms that it is able to enhance the quality of trans-water-air medium communication.