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| | I'm Theresa and I live with my husband and our two children in Chapelknowe, in the south part. My hobbies are Coin collecting, Footbag and Climbing.<br><br>Here is my weblog ... [http://boinc.gorlaeus.net/view_profile.php?userid=120535 Fotografia ślubna toruń] |
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| In [[telecommunication]] and [[electronics]], '''baud''' ({{IPAc-en|ˈ|b|ɔː|d}}, unit symbol "Bd") is synonymous to ''symbols per second'' or ''pulses per second''. It is the unit of [[symbol rate]], also known as ''baud'' or ''modulation rate''; the number of distinct [[symbol (data)|symbol]] changes (signaling events) made to the transmission medium per [[second]] in a digitally [[modulation|modulated]] signal or a [[line code]]. Baud is related to but should not be confused with [[gross bit rate]] expressed in bit/s.
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| However, though technically incorrect, in the case of modem manufacturers baud commonly refers to bits per second. They make a distinction by also using the term characters per second (CPS). In these anomalous cases, refer to the modem manufacturers documentation to ensure an understanding of their use of the term "baud". An example would be the 1996 User's guide for the U.S. Robotics Sportster modem, which includes these definitions.
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| The '''symbol duration time''', also known as [[Unit interval (data transmission)|unit interval]], can be directly measured as the time between transitions by looking into an [[eye diagram]] of an [[oscilloscope]]. The symbol duration time ''T''<sub>s</sub> can be calculated as:
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| :<math> T_s = {1 \over f_s}, </math>
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| where ''f''<sub>s</sub> is the symbol rate.
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| There is also a chance of miscommunication which leads to ambiguity.
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| :'''A simple example''': A baud of 1 kBd = 1,000 Bd is synonymous to a symbol rate of 1,000 symbols per second. In case of a [[modem]], this corresponds to 1,000 tones per second, and in case of a line code, this corresponds to 1,000 pulses per second. The symbol duration time is 1/1,000 second = 1 millisecond.
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| In [[Digital data|digital]] systems (i.e., using discrete/discontinuous values) with [[binary code]], 1 Bd = 1 bit/s. By contrast, non-digital (or [[Analog signal|analog]]) systems use a continuous range of values to represent information and in these systems the exact informational size of 1 Bd varies.
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| The baud unit is named after [[Émile Baudot]], the inventor of the [[Baudot code]] for [[telegraphy]], and is represented in accordance with the rules for [[International System of Units|SI units]]. That is, the first letter of its symbol is uppercase (Bd), but when the unit is spelled out, it should be written in lowercase (baud) except when it begins a sentence.
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| ==Relationship to gross bit rate==
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| {{Main|Gross bit rate}}
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| The symbol rate is related to but should not be confused with gross bit rate expressed in bit/s.
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| The term baud has sometimes incorrectly been used to mean bit rate,{{Citation needed|date=August 2012}} since these rates are the same in old [[modem]]s as well as in the simplest digital communication links using only one bit per symbol, such that binary "0" is represented by one symbol, and binary "1" by another symbol. In more advanced modems and data transmission techniques, a symbol may have more than two states, so it may represent more than one [[bit]] (a bit (binary digit) always represents one of exactly two states).
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| If ''N'' bits are conveyed per symbol, and the gross bit rate is ''R'', inclusive of channel coding overhead, the symbol rate ''f''<sub>s</sub> can be calculated as:
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| :<math> f_s = {R \over N}. </math>
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| In that case ''M''=2<sup>''N''</sup> different symbols are used. In a modem, these may be sinewave tones with unique combinations of amplitude, phase and/or frequency. For example, in a [[64QAM]] modem, ''M''=64, and so the bit rate is ''N''=6 times the baud. In a line code, these may be ''M'' different voltage levels.
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| The ratio might not even be an integer; in [[4B3T]] coding, the bit rate is 4/3 baud. (A typical [[basic rate interface]] with a 160 kbit/s raw data rate operates at 120 kbaud.) On the other hand, [[Manchester coding]] has a bit rate equal to 1/2 the baud.
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| By taking information per pulse ''N'' in bit/pulse to be the base-2-[[logarithm]] of the number of distinct messages ''M'' that could be sent, [[Ralph Hartley|Hartley]]<ref>{{cite book | title = Information Theory and its Engineering Applications | author = D. A. Bell | edition = 3rd | year = 1962 | publisher = Pitman | location = New York |oclc=1626214}}</ref> constructed a measure of the [[gross bitrate]] ''R'' as:
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| :<math> R = f_s \log_2(M). \, </math>
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| ==See also==
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| * [[Bandwidth (computing)|Bandwidth]]
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| * [[Bitrate]]
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| * [[Constellation diagram]], which shows (on a graph or 2D oscilloscope image) how a given signal state (a symbol) can represent three or more bits at once
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| * [[List of device bandwidths]]
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| * [[Modem]]
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| * [[Modulation]]
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| * [[Nyquist rate]]
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| * [[Pulse-code modulation|PCM]]
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| * [[Symbol rate]]
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| ==References==
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| {{Reflist}}
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| ==External links==
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| * {{cite web
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| | title=On the origins of serial communications and data encoding
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| | url=http://www.compkarori.com/dbase/bu07sh.htm
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| | accessdate=January 4, 2007
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| }}
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| * [http://electronicdesign.com/communications/what-s-difference-between-bit-rate-and-baud-rate What’s The Difference Between Bit Rate And baud?], Electronic Design Magazine
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| [[Category:Data transmission]]
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| [[Category:Units of measurement]]
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| [[Category:Units of frequency]]
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I'm Theresa and I live with my husband and our two children in Chapelknowe, in the south part. My hobbies are Coin collecting, Footbag and Climbing.
Here is my weblog ... Fotografia ślubna toruń