FM broadcasting
VHF Radio waves do not travel far beyond the visual horizon, so reception distances for FM stations are usually limited to 30–40 miles (50–65 km) They can also be blocked by hills or buildings.
FM broadcasting in the United States
Because each channel is 0.2 MHz wide, the center frequencies of adjacent channels differ by 0.2 MHz. Because the lowest channel is centered on 87.9 MHz, the tenths digit (in MHz) of the center frequency of any FM station in the United States is always an odd number. FM audio for analog television channel 6 is broadcast at a carrier frequency of 87.75 MHz, and many radios can tune this low; full-power stations ceased analog operations in 2009 under FCC orders, but a few low-power stations are still operated solely for their right to use this frequency and broadcast only nominal video programming, if any (these, too, will reportedly eventually be forced to shut down). For the same reason, assignment restrictions between TV stations on channel 6 and nearby FM stations are stringent: there are only two stations in the United States (KSFH, a 10-watt student station in Mountain View, California; and CSN International translator K200AA in Sun Valley, Nevada) licensed to operate on 87.9 MHz, both because they were forced off of other channels. Therefore, in effect, the FM broadcast band comprises only FM channels 201 (88.1 MHz) through 300 (107.9 MHz).