Alternatively, each can carry one channel of a stereo broadcast. The two digital channels can also send two separate programs. Only one of the digital signals needs to be transmitted if spectrum conservation is a primary concern. The spectrum is shown in Figure 1. The digital signals are more efficient than analog.
Broadcasters can reduce power.
Error correction techniques developed for weak-signal space communications can actually detect and repair noise hits. Your CD player uses similar technology to correct errors. So the technology is available for adaptation to the unique problems of short-wave transmission. The Telefunken engineers claimed that quality equal to today's analog FM radio will certainly be possible. They even held out hope of CD quality audio.