Signal transmission using bipolar amplitude and frequency modulation of carrier oscillation

Introduction. The article considers the transmission of signals over a communication channel using bipolar amplitude and frequency modulation of the carrier harmonic oscillation. To organize an information channel, the positive half-waves of the carrier oscillation are modulated by one of the transmitted signals in amplitude or frequency, and the negative half-waves are modulated in amplitude or frequency by another signal. Goal. To demonstrate the possibility of transmitting two signals via a communication channel using bipolar amplitude and frequency modulation of the carrier oscillation with a limited bandwidth of the communication channel. Problem statement. Provide a mathematical description of the carrier oscillation with bipolar amplitude and frequency modulation. Determine the requirements for the frequency characteristics of the communication channel. Method. The research is based on the spectral representation of signals in the communication channel with bipolar amplitude and frequency modulation. Results. Analytical relationships are obtained for describing the carrier harmonic oscillation with bipolar amplitude and frequency modulation taking into account the limited bandwidth of the communication channel. The influence of the bandwidth of the communication channel on the quality of signal transmission is determined. Conclusion. The research has shown the possibility of transmitting two signals using one carrier oscillation via a communication channel with a limited bandwidth. In the case of using amplitude modulation of half-waves of the carrier oscillation by signals, the bandwidth of the communication channel must be no less than twice the greater modulation frequency of the transmitted signals. With frequency modulation, transmission of two independent signals is possible only with angular modulation indices much less than one.