Home > Sideband

Amplitude modulation of a carrier wave normally results in two sidebands. The frequencies above the carrier frequency constitute the upper sideband (USB), 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.

If part of one sideband and all of the other remain, it is called vestigial sideband, used mostly with television broadcasting, which would otherwise take up an unacceptable amount of bandwidth. Transmission in which only one sideband is transmitted is called single-sideband transmission (SSB, particularly USB and sometimes LSB), used mainly in amateur radio.

In many cases, paticularly in SSB amateur radio, a suppressed carrier is used, significantly reducing the amount of electrical power used (by up to 12 times), while still leaving the audioAudio can mean: sound that can be heard electronic or other signals of frequencies audible to humans (about 20--20,000 Hz) broadcasting or reception of sound high-fidelity sound reproduction sound recording and reproduction in general "I hear" in the Lati or other information present in the sideband. In this case, a beat frequency oscillatorA beat frequency oscillator or BFO in radio telegraphy, is a dedicated oscillator used to create an audio frequency signal for carrier wave transmissions to make them audible, as they are not broadcast as such. The signal from the BFO is then heterodyned must be used at the receiverThe word receiver has a number of different meanings: In communications and information processing, a receiver is the recipient ( observer) of a message ( information), which is sent from a source ( object). Receivers decode messages. A receiver (radio) i to reconstitute the signalA signal may refer to: an abstract element of information, or, more exactly, usually a flow of information (in either one or several dimensions). See Signal (information theory . in electronics) a signal is any physical phenomenon that can be modeled as a.

Sidebands are also what cause interferenceIn communications, interference is anything which alters, modifies, or disrupts a message; as it travels along a channel, between a source and a receiver. Below is an article about the physical phenomenon of wave interference. See also the legal concept o to adjacent channelIn broadcasting an adjacent channel is an AM, FM, or TV channel that is next to another channel. First-adjacent is immediately next to another channel, second-adjacent is two channels away, and so forth. Information on adjacent channels is used in keepings, and therefore they must be suppressed by filterThe term filter may refer to: Filter (chemistry) — a device to separate mixtures Electrostatic Dust Filter Filter (mathematics) — a certain kind of subset of a partially ordered set Filter program — in Unix, any program with standard I/O streams. Any softs, either before or after modulation (or often both). In frequency modulation (FM), subcarriers above 75 kHz are suppressed to a small percentage of modulation, and are prohibited above 99 kHz altogether, in order to protect the ±75 kHz normal deviation and ±100 kHz channel boundaries.

Source: partly from Federal Standard 1037C in support of MIL-STD-188