There’ve been a couple of interesting developments out of the HD Radio trenches over the last few months. Both are touted as advanced “applications” for utilizing the HD Radio system — but in reality they’re band-aids that seek to fix fundamental flaws with the technology itself.
The first involves transmitter-manufacturer Nautel and its experiments with FM-HD multiplexing. This practice is inherent to the DAB/DAB+ radio systems adopted in Europe, Asia, and elsewhere: instead of every station having its own transmission infrastructure, stations send a stream to a multiplex transmitter where it’s combined with other stations and broadcast as a unifed signal. Instead of tuning to a particular frequency, DAB/DAB+ receivers look for the data-flags of the desired station and, once found, decode only that stream. In this configuration, DAB/DAB+ multiplexes can broadcast 10 or more channels of programming on a single unified digital radio signal.