Research on FPGA-based modulation algorithm for directional sound sources

The directional sound source system can transmit the sound beam in a directional manner to achieve high directional sound propagation, which has a wide application prospect in the fields of public security, armed police, maritime surveillance and fishery administration, military, airport bird repelling, civil disaster relief department, border control, etc. The basic principle is to use the nonlinear characteristics of ultrasonic waves propagating in the air, and to self-demodulate the frequency-dependent audible sound signal during the propagation process. In this paper, the algorithms related to signal modulation and air nonlinear demodulation are studied, and the algorithms are derived using bilateral and single sideband modulation, respectively. The working principle of the digital control oscillator is described, a soft IP core is used to design the digital control oscillator, the waveform generation algorithm of the digital control oscillator is analyzed in detail, the phase addition jitter technique is introduced, and a high precision digital controllable sine wave is generated after simulation. The top-level documentation of the directional sound source system has been designed to facilitate modular applications. The system functions have been simulated to achieve the desired goal of bilateral band modulation and single sideband modulation.