bandwidth

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Related to Bandwith: bandwidth, broadband, Internet bandwidth

bandwidth

1. The range of frequencies over which an instrument, such as a radio telescope, is sensitive. A wide bandwidth gives good sensitivity to sources that emit over a wide range of frequencies (e.g. by synchrotron emission), whereas a narrow bandwidth gives good sensitivity to spectral lines.
2. (coherence bandwidth) The range of frequencies over which electromagnetic or other emissions from a source maintain coherence.

bandwidth

[′band‚width]
(communications)
The difference between the frequency limits of a band containing the useful frequency components of a signal.
A measure of the amount of data that can travel a communications path in a given time, usually expressed as thousands of bits per second (kbps) or millions of bits per second (Mbps).

bandwidth

(communications)
The difference between the highest and lowest frequencies of a transmission channel (the width of its allocated band of frequencies).

The term is often used erroneously to mean data rate or capacity - the amount of data that is, or can be, sent through a given communications circuit per second.

bandwidth

(1) Computer people may use the term for capability and time. For example, "not enough bandwidth to get the job done" means not enough staff or time to do it. Its true meaning follows.

(2) The transmission capacity of an electronic pathway such as a communications line, computer bus or computer channel. Digital bandwidth is the number of pulses per second measured in bits per second (bps). For example, Ethernet transmits at different speeds, including 10 Mbps, 100 Mbps and 1000 Mbps (see Mbps and baseband).

When transmitting alternating frequencies, as with all wired analog, many wired digital and most wireless communications, the bandwidth is the difference between the highest and lowest frequencies, measured in cycles per second, or Hertz (Hz). For example, 802.11n Wi-Fi transmits in 20 MHz and 40 MHz channels within the 2.4 GHz and 5 GHz bands. The 20 and 40 MHz channel frequencies are the bandwidths, and each channel is divided into subchannels.

From Hertz to Bits - A Complicated Process
When using alternating frequencies for digital transmission, the frequencies are modified (modulated) by the digital input. Using the 802.11n Wi-Fi example, the resulting bit rate can range from 6.5 Mbps to 600 Mbps. This extremely wide range is determined by the signal strength and interference in the environment at any given moment. Any one of more than 30 combinations of channel bandwidth (20, 40 MHz), modulation scheme, error correction rate, channel spacing and number of antennas may be selected, on a packet-by-packet basis. See modulation, video bandwidth, space/time and bandwidth junkie.


Bandwidth in Hertz to Bandwidth in Bits
This quadrature PSK (QPSK) example is one of the simplest modulation schemes. Each set of two input bits modifies the carrier into four phase angles. The amplitude remains constant, unlike QAM modulation, in which the amplitude is varied (see QAM).











References in periodicals archive ?
It is difficult to combine the diode with the E-shaped arm (L), as the arm (L) is not long enough and the rejection bandwith changed with the diversification of the arm (L).
(1999) Recommendations for standardization and specifications in automated electrocardiography: Bandwith and digital signal processing.
He admits he enjoys chatting with ham radio friends in the car to and from work, but said sending and receiving Morse code requires much less bandwith on all frequencies.
Data management in the application will have to be done considering device storage and internet bandwith. There should be a balance between the two, conidering that not all data connections are free, and the more bandwith the application uses the more the carrier will charge the user.
It will then be ready to run a growing range of web based applications, including video distribution, this is protected by Play Ready DRM.Making use of adaptive streaming technology adjusting video resolution according to available IP bandwith, Altech multimedia's hybrid box will ensure a smooth and uninterrupted user viewing experience.
As a precautionary measure, the bandwith for internet was decreased considerably thereby leaving the customers without any mobile internet.
Constant Size Loading bandwith elements [12] Yes 0.06[lambda]g x 0.2[lambda]g Si varactor [13] Yes > (0.15[lambda]g x 0.13[lambda]g Si varactor [14] No 0.25[lambda]g x 0.11[lambda]g Si varactor this work No 0.15[lambda]g x 0.07[lambda]g Si varactor Ref.
But, he added, the new services would require "a ton of bandwith," a need for online infrastructure that they may not yet be able to meet.
It's true that the rush of readers coming to the Lehrer story was much larger than normal, but I am assured by our IT team that we had more than sufficient bandwith and server memory to handle it.
Bandwith available for voice, video and Internet are amazing, as in the case of copper the bandwith is limited and has less speed.Ee In the case of FTTH, a single fibre will be terminated to a CPE (Customer Premises Equipment) with which the customer can avail all the three integrated services at a much higher bandwidth rather than providing different services through multiple copper cables with a limitation on the bandwidth," he added.
Turner, who hosted a weekly webcast from his home in suburban New Jersey, claimed the group took his website offline with a denial-of-service attack and cost him thousands of dollars in bandwith bills due to the group flooding his site.
Reuters' reports last year said that the telecommunications services firm could be attractive for mobile operators seeking increased bandwith to meet growing demand for mobile Internet.Country: UK, Sector: TelecommunicationsTarget: Cable & Wireless Worldwide plcBuyer: Vodafone PlcType: Corporate acquisitionStatus: Bidding, SpeculationComment: Possible bid reported at USD1.1bn.