A Simultaneous Analog-Digital Signal Transmission System Based on PFM and PWM

Simultaneous analog and digital signal transmission is useful for indoor applications. A simultaneous transmission of single channel analog audio signals and digital temperature values is illustrated in this paper. The analog and digital signals are firstly modulated by the pulse frequency modulation and the pulse width modulation respectively, which are then mixed together and transmitted with the infrared communication via a single bus. The received mixed signal is then demodulated with a certain algorithm. An ultra-low power repeater can be utilized in the system to forward the mixed modulated signal so that a required communication distance can be reached. The whole wireless communication system is cost efficient. Both simulation results and experiments for a real implementation show that the proposed method is effective.