Simulcast process
The simulcast method is the simultaneous transmission of an analog amplitude-modulated signal and a signal transmitted using the Digital Radio Mondiale (DRM) method in the same (SingleChannel Simulcast - SCS) or an adjacent channel (MultiChannel Simulcast - MCS).
For this purpose, the DRM signal is modulated to the carrier using the quadrature modulation method and the analog signal is then modulated onto this signal, using conventional amplitude modulation or AM-compatible single sideband modulation, depending on the available bandwidth. The simulcast method has the advantage over the pure DRM method that the signal can also be received by old AM receivers.
However, compared to the pure DRM process, this method has the disadvantage of a poorer transmission quality, and even when receiving with conventional AM radios, there may be more noise than when receiving a pure AM station.