Telecommunication
The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel, which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in the neighborhood of 94.5 MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighborhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180 kHz (kilohertz), centered at frequencies such as the above, which are called the "carrier frequencies". Each station in this example is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system.
Felixstowe
Radio Caroline ship MV "Caroline" was outside the three-mile limit at Easter 1964. It was the very first UK radio station aboard a ship in the North Sea, and intended to break the monopoly of the BBC. Radio Caroline had about seven million listeners in its first week on air. The station's slogan was "Your all-day music station", and it initially broadcast from 6am to 6pm, seven days a week. The transmitter had a power of 10 kW on 199 metres – 1.520 kHz. The ship moved to waters off the Isle Of Man in summer 1965 to become Radio Caroline North, while MV "Mi-Amigo" of Radio Atlanta on 201 metres became Radio Caroline South, broadcasting on first 199 later on 259 metres – 1.178 kHz with 50 kW of power on medium wave. Later the ship moved to waters off Clacton-On-Sea, Essex.