With the introduction of stereo FM, the MPX signal was born, or was it the other way around? Regardless, the fact is that the multiplexed broadcast signal to this day represents all the artistic and technical efforts of radio production as an electrical signal. So, it is a valuable thing, this MPX signal.
In the pre-digital era, analog MPX demanded a lot of attention. Only proven experts were entrusted with monitoring and distributing MPX, which relentlessly relayed the effects of any error to all listeners.
This is the reason for the continuous effort to keep interferences away and to reduce the components within the MPX signal path. As a result, the time axis shows that there was and is an increasing integration density across both signal domains.
Digitization was a milestone in MPX signal creation and processing and resulted in the AES192 format. In the broadcast world, it describes the AES format sampled at 192kHz. It allows the transport of the entire MPX spectrum in the digital domain.
The advantages of such an approach to FM-MPX transmission are many. Most importantly, all MPX generation equipment can be located in the studio. Furthermore, if the STL, including the codecs, already supports AES192, only an AES192 capable exciter is needed at the transmitter site.