Inaudible transmission system with selective dual frequencies robust to noisy surroundings

This paper proposes an inaudible communication method with high reception rate which is resistant to ambient noise using selective dual frequency. Dual frequencies allow combine more signals than a single frequency in a given frequency band, thereby reducing the error recognition rate. The proposed system also measures the frequencies occurring in the environment. After that, the system selectively uses frequencies in the unmeasured band to avoid interference and increase reception. Inaudible sound uses a high frequency of 16-22kHz, which humans hard to hear, but microphones can recognize. Thus, this method of transmission allows the use of speakers and microphones inside smart devices and consumer electronics. It can be used for near field communication instead of Bluetooth, NFC, Zigbee, and Wi-Fi. We provide a communication solution that increase the reception rate through different speaker outputs, variable frequency bands, and hardware direction. Experiments uses selective dual frequency resulted in the reception rate of at most 90% for distances of 12m, respectively.