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In
electronicsElectronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
,
voiceband means the typical human hearing frequency range that is from 20 Hz to 20 kHz. In
telephonyIn telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, it means the frequency range normally transmitted by a
telephone lineA telephone line or telephone circuit is a single-user circuit on a telephone communication system...
, generally about 200–3600 Hz.
Frequency-division multiplexingFrequency-division multiplexing is a form of signal multiplexing which involves assigning non-overlapping frequency ranges to different signals or to each "user" of a medium.- Telephone :...
in telephony normally uses 4 kHz carrier spacing. The
roll-offRoll-off is a term commonly used to describe the steepness of a transmission function with frequency, particularly in electrical network analysis, and most especially in connection with filter circuits in the transition between a passband and a stopband...
rate, or rate at which the amplitude of a signal drops off near the upper and lower limits can vary with the design of the
band-pass filterA band-pass filter is a device that passes frequencies within a certain range and rejects frequencies outside that range.Optical band-pass filters are of common usage....
s.
The question of frequency spacing was addressed at an international meeting in the 1930s. Germany and Britain favored 2 kHz spacing, while the Netherlands and some other countries preferred 6 kHz. The question was compromised at the American position, which was the 4 kHz spacing that remained standard and also fixed the standard PCM sample rate at 8 kHz, which in turn defines what "voiceband" means for this purpose. The abandonment of
in-band signalingIn telecommunications, in-band signaling is the sending of metadata and control information in the same band or channel used for data.-Telephone:...
in the late 20th century made available a larger voiceband for
modemA modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
s and voices.
See also
- A-weighting
A Weighting curve is a graph of a set of factors, that are used to 'weight' measured values of a variable according to their importance in relation to some outcome. The most commonly known example is frequency weighting in sound level measurement where a specific set of weighting curves known as A,...
- Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
- Frequency-division multiplexing
Frequency-division multiplexing is a form of signal multiplexing which involves assigning non-overlapping frequency ranges to different signals or to each "user" of a medium.- Telephone :...
- Time-division multiplexing
Time-division multiplexing is a type of digital multiplexing in which two or more bit streams or signals are transferred apparently simultaneously as sub-channels in one communication channel, but are physically taking turns on the channel. The time domain is divided into several recurrent...
- Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...