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Mediumwave radio transmissions are those between the frequencies of 300 kHz and 3000 kHz. In most of the world, mediumwave serves as the most common band for broadcasting. The standard AM broadcast band is 535kHz to 1705kHz in North America, but remains only up to 1615kHz elsewhere.Mediumwave signals have the properties of following the curvature of the earth (the groundwave) and reflecting or refracting off the ionosphere at night ( skywave). This makes this frequency ideal for both local and continent-wide service, depending on the time of day. For example, during the day a radio receiver in the state of Maryland is able to receive reliable but weak signals from high-power stations WFAN, 660 kHz, and WOR, 710 kHz, 400 km in New York City, due to groundwave propagation. At night, the same receiver picks up signals as far away as Mexico City and Chicago reliably.
In the Americas, mediumwave stations are separated by 10 kHz and have two sidebands of ±5kHz. In the rest of the world, the separation is 9 kHz, with sidebands of ±4.5kHz. This provides adequate audio quality for voice, but is insufficient for high-fidelity broadcasting, which is reserved for the VHFVery high frequency (VHF is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). Common uses for VHF are FM radio broadcast at 88-108 MHz and television broadcast (together with UHF). VHF is also commonly used for terrestri FMFM redirects here, for alternate uses, see Fm Frequency modulation (FM) is the encoding of information in either analogue or digital form into a carrier wave by variation of its instantaneous frequency in accordance with an input signal. This is typically bands.
In the United States, in SeptemberSeptember is the ninth month of the year in the Gregorian Calendar, with 30 days. The name comes from the Latin septem for " seven" September was originally the seventh month of the year, before January and February were inserted. In Greek civilization, S 20022002 is a common year starting on Tuesday (see link for calendar). 2002 was the first palindromic year since 1991 and the last until 2112. 2002 was also designated: International Year of Ecotourism and Mountains National Science Year in the United Kingdom, the Federal Communications CommissionThe Federal Communications Commission (FCC) is an independent United States government agency, created, directed, and empowered by Congressional statute. The FCC was established by the Communications Act of 1934 as the successor to the Federal Radio Commi approved the iBiquityiBiquity is a company formed by the merger of USA Digital Radio and Lucent Digital Radio, with the goal of creating an in-band on-channel digital radio system for the United States. in-band on-channelIn-band on-channel IBOC is a method of transmitting digital and analog radio broadcast signals simultaneously on the same frequency. By utilizing a subcarrier, digital information is "piggybacked" on a normal AM or FM analog signal, thus avoiding any comp (IBOC) system of digital broadcasting , which is meant to improve the audio quality of signals. The Digital Radio Mondiale (DRM) IBOC system has been approved by the ITU for use outside the Americas.
Radio spectrum
