With very few exceptions, all digital broadcasting is done on commercial (non government)stations here in the states. It is done voluntarily by the stations. There is no current requirement that they have any digital broadcast. Many of the newer receivers are able to pick up the digital broadcast, but there is no requirement that all receivers be equipped with digital receivers. I have a digital receiver and sound is great (CD quality) but reception is not as wide spread as the analog signal. The receiver will automatically switch to analog at the loss of the digital signal. On a side note, at one of the transmitter sites here, 7 FM stations share 1 antenna for there analog broadcast. A very large combiner connects all 7 transmitters to the single antenna.
