CARRIER WAVE:
In telecommunications, a carrier wave, or carrier is a waveform (usually sinusoidal) that is modulated (modified) with an input signal for the purpose of conveying information.[1] This carrier wave is usually of much higher frequency than the input signal. The purpose of the carrier is usually either to transmit the information through space as an electromagnetic wave (as in radio communication), or to allow several carriers at different frequencies to share a common physical transmission medium by frequency division multiplexing (as is used in, for example, a cable television system). Frequency modulation (FM) and amplitude modulation (AM) are commonly used methods to modulate the carrier. In the case of single-sideband modulation (SSB) the carrier is suppressed (and in some forms of SSB eliminated). The carrier must be reintroduced at the receiver by a beat frequency oscillator (BFO). The frequency for a given radio or television station is actually the carrier wave's center frequency.
RADIO:
Radio frequency (RF) is a rate of oscillation in the range of about 30 kHz to 300 GHz, which corresponds to the frequency of electrical signals normally used to produce and detect radio waves. RF usually refers to electrical rather than mechanical oscillations, although mechanical RF systems do exist (see mechanical filter and RF MEMS). Radio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light.[1] Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space. Information is carried by systematically changing (modulating) some property of the radiated waves, such as amplitude, frequency, phase, or pulse width. When radio waves pass an electrical conductor, the oscillating fields induce an alternating current in the conductor. This can be detected and transformed into sound or other signals that carry information.
MEDIUM FREQUENCY:
Medium wave (MW) is that part of the medium frequency (MF) radio band used mainly for AM broadcasting. For Europe the MW band allocated for broadcasting is from 526.5 kHz to 1606.5 kHz[1] and in North America an extended MW broadcast band goes from 535 kHz to 1705 kHz.[2]
BAND:
A band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose.
DIAPHRAGM:
In a loudspeaker, a diaphragm (generally, but not exclusively cone shaped) is the thin, semi-rigid membrane attached to the voice coil, which moves in a magnetic gap,
vibrating the diaphragm, and producing sound. Diaphragms are also found in headphones, and microphones.
CONTINUOUS WAVE:
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio transmission, in which a carrier wave is switched on and off. Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave transmission.
SIDEBAND:
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier. All forms of modulation produce sidebands.[citation needed] Amplitude modulation of a carrier wave normally results in two mirror-image sidebands. The signal components above the carrier frequency constitute the upper sideband (USB) and those below the carrier frequency constitute the lower sideband (LSB). In conventional AM transmission, the carrier and both sidebands are present, sometimes called double sideband amplitude modulation (DSB-AM). In some forms of AM the carrier may be removed, producing double sideband with suppressed carrier (DSB-SC). An example is the stereophonic difference (L-R) information transmitted in FM stereo broadcasting on a 38 kHz subcarrier. The receiver locally regenerates the subcarrier by doubling a special 19 kHz pilot tone, but in other DSB-SC systems the carrier may be regenerated directly from the sidebands by a Costas loop or squaring loop. This is common in digital transmission systems such as BPSK where the signal is continually present.
