Band-width

Treatment of the signal

The band-width is the width, measured in hertz, of a beach of frequencies f₂ - f₁. It can also be used to describe a signal, in this case the term indicates the difference between highest and more the low frequency of the signal (what one calls also the obstruction spectral). It is usually noted B or BP.

The Band-width to -3 dB (Decibel) of an amplifier is the range of Fréquence S where the profit in tension of the amplifier is higher than the maximum profit minus three decibels. If one does not reason in decibel, that corresponds to the frequency band where the profit in tension higher than the maximum profit is divided by root of two, which corresponds to a division of the power provided to the load by two. Occasionally one meets broader band-widths, for example the band-width to -6 dB, frequency band where the profit in tension is higher than half of the maximum profit.

In a more general way, the band-width with - X dB is the frequency band where the profit of the filter is higher than the maximum profit divided by 10 x/20 … for -3dB: 10 0,15 = $\ sqrt {2}$ (≈1,41)

The extreme points of the band-width are called pulsations of cut .

Data processing and networks

In the field of data processing, the band-width indicates - by abuse language - a flow of information. The exact term is the binary debit.

The origin of the term is an analogy with the band-width in electronic. The band-width of a cable measuring the maximum number of oscillations a second a signal can take there without being too much attenuated, if the signal is that of a data-processing connection like a connection series, the number of oscillations will reflect the number of information which one can transfer during one second.

The band-width can relate to the flow of a peripheral (such as a memory, an hard drive, etc) or of a medium of communication (network, bus, etc) or in a general way any flow of information as between the Processeur and the Mémoire hiding place.

One generally measures this band-width in Octet S (byte in English) by second (o/s, or in English “Byte per second”, B/s) or in bits per seconds (bit/s or bps ), more generally used by the suppliers of access Internet to give the maximum capacity of a subscription.

Examples of band-widths

telephone Signal: 3400Hz
Signal of television STAKE for 1 channel:

See too

95e centile

References

Simple: Bandwidth

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