Response of an ultrasonic communication channel in air

The authors propose a model for estimating the response of an ultrasonic communication channel, where a specific type of capacitive transreceivers was used to give an effective bandwidth of over 1 MHz. Apart from the responses of transreceivers, the channel response at each location within the radiated field can be determined by attenuation response and special field response. The driving signal used to verify the model was a quadrature phase shift keying (QPSK) signal centred at 300 kHz, and with a signalling rate of 400 kbps. Simulations were firstly carried out to identify the variations in waveform as well as spectrum caused by predicted response at several coordinates. This is then compared with experimental results, and good agreements were found between the two.