AGAIN, the MAIN problem with the slow adoption of DRM has been broadcasters' poor choice of 64 QAM modulation on the shortwave bands. Even AIR experimented with 64 QAM with ultra low bit-rates of ~ 8 kbps and the results like RNZI's use of 64 QAM were sub-optimal for shortwave when modest interference and propagation degraded the signal. * 64 QAM modulation has NEVER and will NEVER work well, i.e. reliably, on shortwave as thousands of logs demonstrate. Bit-rate certainly plays a role in a listener's ability to reliably decode a digital broadcast, but that role is clearly secondary to the modulation scheme. Unfortunately, this irresponsible use of 64 QAM modulation by digital broadcasters has given DRM a tarnished image on shortwave which will ONLY be overcome with the widespread adoption of 16 QAM modulation.
* RNZI's transmitter is located in a nearly perfect spot as well and it still didn't function reliably enough under the FREQUENTLY sub-optimal conditions found on shortwave.
Last edited by tpreitzel : 08-02-2018 at 00:13.