Since 2002 every AM broadcaster in the United States is allowed to broadcast digitally by using HD Radio – a system that permits spreading to 3 thematic channels and provides services, such as the visualisation of songs’ or artists’ names (in addition to the analogue signal – still receivable by traditional receivers). However, this system can’t always be used; in fact, the digital signal occupies 40 kHz of the band – compared to the standard frequency range of 20 kHz – making digital broadcasting not possible if other radio stations are operating on nearby frequencies.
Since listening to AM stations has become difficult due to the rising of radio electric interferences – caused by increasing proliferation of electronic devices- FCC is trying to promote and increase AM stations ratings by proposing broadcasters to switch to all digital broadcasting, meeting the standards set by the regulations (not exceeding 20 kHz) and thus minimising interferences. This is just one of the various initiatives taken by the American regulator almost one hundred years from the first radio transmission in the US: the Agency has also allowed the opening of some new broadcasting facilities.
Today, only one AM station is all digital
Today just one broadcaster in the US is allowed to operate all digital on AM. It is WWFD – a broadcaster from Frederick, Maryland (70 km from Washington). Since 16th July, 2019 this broadcaster – better known as The Gamut – transmits its digital-only AM signal on 820 kHz. Additionally, the station transmit its digital signal on 103.5 MHz in HD (a standard that allows to transmit up to four channels on the same frequency). Today -in the United States – 4,580 broadcaster are operating on AM and 10,850 on FM, divided in commercial (6,728) and non-commercial (4,122). In total there are 20,342 FM transmitters. You can find the complete list on FMList.
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