Modulation and demodulation of a combination of analog and digital signals

摘要

In order to transmit a combination of modulated analog and digital signals in which a digital data signal (Dl) is modulated by means of multicarrier quadrature amplitude modulation and an analog signal (Al) is modulated by means of single side band modulation (SSB), a multicarrier quadrature amplitude base modulation of the digital data signal (Dl) and a SSB base modulation of the analog signal (Al), is performed. Corresponding components of the modulated and optionally upsampled digital (o'I(n),o'Q(n)) and analog (s'''I(n) s'''Q(n)) signals are added, and a carrier frequency modulation (4) of the added components is performed. In a receiver, the same carrier frequency demodulator 8 is used for the superimposed modulated analog and digital signals, which then are base band demodulated separately (6,7). The invention reduces the total computational effort for modulating the digital and analog signals by performing the carrier frequency modulation or demodulation only once.