2006-12-18 16:48:55 · 2 answers · asked by Ruth929 2 in Consumer Electronics ➔ Other - Electronics
It's digital modulation.
FM = Frequency Modulation
AM = Amplitude Modulation
DM = HD = Digital Modulation. In recent times, with the popularity of HD TV, marketers have started calling digital modulation HD to try and get more attention for it. It has been around for a decade or more. Digital modulation can be carried on an FM or AM signal, and results in a very high quality signal that does not interfere with it's carrier signal... so an existing broadcast license can send it out on top of their old signal wihtout needing to get another license.
2006-12-18 16:54:18 · answer #1 · answered by Jay 3 · 0⤊ 0⤋
HD Radio is iBiquity's trademark for their digital broadcast format used over commercial AM and FM bands in the US.
2006-12-19 10:18:32 · answer #2 · answered by CMass Stan 6 · 0⤊ 0⤋