Double-sideband suppressed-carrier transmission
Overview
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
in which (a) frequencies produced by amplitude modulation
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
are symmetrically spaced above and below the carrier frequency
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
and (b) the carrier level
Carrier wave
In telecommunications, a carrier wave or carrier is a waveform that is modulated with an input signal for the purpose of conveying information. This carrier wave is usually a much higher frequency than the input signal...
is reduced to the lowest practical level, ideally completely suppressed.
In the double-sideband suppressed-carrier transmission (DSB-SC) modulation, unlike AM, the wave carrier is not transmitted; thus, a great percentage of power that is dedicated to it is distributed between the sidebands, which implies an increase of the cover in DSB-SC, compared to AM, for the same power used.
DSB-SC transmission is a special case of Double-sideband reduced carrier transmission
Double-sideband reduced carrier transmission
Double-sideband reduced carrier transmission : transmission in which the frequencies produced by amplitude modulation are symmetrically spaced above and below the carrier and the carrier level is reduced for transmission at a fixed level below that which is provided to the modulator.Note: In...
.
This is used for RDS (Radio Data System
Radio Data System
Radio Data System, or RDS, is a communications protocol standard for embedding small amounts of digital information in conventional FM radio broadcasts. RDS standardises several types of information transmitted, including time, station identification and programme information.Radio Broadcast Data...
) because it is difficult to decouple.
This is basically an amplitude modulation
Amplitude modulation
Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...
wave without the carrier therefore reducing power wastage, giving it a 100% efficiency rate.
