| |
|
AM Broadcast Band
|
The band 535-1705 kHz is used for AM broadcast in the U.S. (among other countries). Stations are assigned center frequencies every 10 kHz starting at 540 kHz and ending at 1700 kHz, and each analog broadcast has a bandwidth of approximately 5 kHz. There is a total of 117 available AM broadcast frequencies in the band.
Because radio signals in this range can travel a long distance by bouncing off the ionosphere (especially at night, when the densest parts of the ionosphere are at very high altitude), careful frequency coordination of the AM broadcast band is required. Some stations are required to reduce power at night, or go off the air completely, to avoid interference to other stations using the same frequency.
Some AM stations are also transmiting an "In-Band, On-Channel" (IBOC) digital signal, which is implemented using far-out sidebands of the analog signal. Digital broadcasting has not had a large uptake in the U.S., and there are lingering problems and concerns with the digital sidebands creating interference to other stations, especially at night when propagation can reach great distances.
As of March, 2012, there were 4,762 AM broadcast stations on the air in the U.S., or about 41 stations per channel on average.
|
Frequency Bands |
| Band | Use | Service11 | Table |
| 535 - 1705 kHz | AM Broadcast | Broadcasting | N |
|
|
|
|
|