Symbol rate - Revision history

en>Dondervogel 2: /* Relationship to gross bitrate */ megabaud

2014-12-09T17:56:06Z

Relationship to gross bitrate: megabaud

← Older revision		Revision as of 19:56, 9 December 2014
Line 1:		Line 1:
	~~In [[plasma physics]], an '''electromagnetic electron wave'''~~ is ~~a [[Waves in plasmas\|wave]] in a [[plasma (physics)\|plasma]] which has a [[magnetic field]] component and in which primarily the [[electron]]s oscillate.~~		The author is known by the name of Numbers Lint. Hiring is her working day job now and she will not alter it anytime quickly. What I love performing is performing ceramics but I haven't produced a dime with it. Puerto Rico is where he's always been living but she needs to move because of her family members.<br><br>Here is my blog :: [http://www.pinaydiaries.com/blog/104745 http://www.pinaydiaries.com]

	~~In an unmagnetized plasma, an electromagnetic electron wave is simply a [[light]] wave modified~~ by the ~~plasma. In a magnetized plasma, there are two modes perpendicular to the field, the O and X modes, and two modes parallel to the field, the R and L waves.~~

	~~==Cut-off frequency and critical density==~~
	~~In an unmagnetized plasma in the high frequency or low density limit, i.e. for <math>\omega >> (4\pi n_ee^2/m_e)^{1/2}</math>~~
	or
	~~<math>n_e << m_e\omega^2\,/\,4\pi e^2</math>,~~
	~~the wave speed is the [[speed~~ of ~~light]] in vacuum~~. As the density increases, the [[phase velocity]] increases and the [[group velocity]] decreases until the '''[[cut-off frequency]]''' where the light frequency is equal to the plasma frequency. This density is ~~known as the '''critical density''' for the [[angular frequency]] ω of that wave~~ and is given by <ref name=Chen>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=116\|edition=2nd\|isbn=0-306-41332-9}}</ref>

	~~:<math>n_c = \frac{\varepsilon_o\,m_e}{e^2}\,\omega^2</math>~~.

	~~If the critical density~~ is ~~exceeded, the plasma is called '''over-dense'~~''.

	In a ~~magnetized plasma, except for the O wave, the cut-off relationships are more complex.~~

	~~==O wave==~~
	~~The '''O wave''' is the "ordinary" wave in the sense that its [[dispersion relation]] is the same as that in an unmagnetized plasma. It is [[Plane polarization\|plane polarized]]~~ with
	~~'''E'''<sub>1</sub> \|\| '''B'''<sub>0</sub>.~~
	~~It has a cut-off at the [[plasma frequency]].~~

	~~==X wave==~~
	~~The '''X wave''' is the "extraordinary" wave because~~ it ~~has a more complicated dispersion relation~~. It is ~~partly transverse (with~~ '~~''E'''<sub>1</sub>⊥'''B'''<sub>0</sub>)~~
	~~and partly longitudinal~~. ~~As the density is increased, the phase velocity rises from ''c'' until the cut-off at ω~~<~~sub~~>R<~~/sub~~> is reached. As the density is further increased, the wave is evanescent until the resonance at the upper hybrid frequency ω<sub>h</sub>. Then it can propagate again until the second cut-off at ω<sub>L</sub>. The cut-off frequencies are given by <ref name=Chen2>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=127\|edition=2nd\|isbn=0-306-41332-9}}</ref>
	:~~<math>\omega_R = \frac{1}{2}\left~~[ ~~\omega_c + (\omega_c^2+4\omega_p^2)^{1/2} \right]</math>~~
	:~~<math>\omega_L = \frac{1}{2}\left[ -\omega_c + (\omega_c^2+4\omega_p^2)^{1/2} \right]<~~/~~math>~~
	~~where <math>\omega_c<~~/~~math> is the [[electron cyclotron resonance]] frequency, and <math>\omega_p</math> is the electron [[plasma frequency]]~~.

	~~==R wave and L wave==~~
	~~The '''R wave''' and the '''L wave''' are right-hand and left-hand circularly polarized, respectively~~. ~~The R wave has a cut-off at ω<sub>R<~~/~~sub> (hence the designation of this frequency) and a resonance at ω<sub>c<~~/~~sub>. The L wave has a cut-off at ω<sub>L<~~/sub> and no resonance. R waves at frequencies below ω<sub>c</sub>/2 are also known as '''whistler modes'''. <ref name=Chen3>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=131\|edition=2nd\|isbn=0-306-41332-9}}</ref>

	~~==Dispersion relations==~~
	~~The [[dispersion relation]] can be written as an expression for the frequency (squared), but it is also common to write it as an expression for the [[index of refraction]] ''ck''/ω (squared).~~

	~~{\| class="wikitable"~~
	~~\|+ Summary of electromagnetic electron waves~~
	\|-
	~~! conditions !! dispersion relation !! name~~
	\|-
	~~\| <math>\vec B_0=0</math> \|\| <math>\omega^2=\omega_p^2+k^2c^2</math> \|\| light wave~~
	\|-
	~~\| <math>\vec k\perp\vec B_0,\ \vec E_1\\|\vec B_0</math> \|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2}{\omega^2}</math> \|\| O wave~~
	\|-
	~~\| <math>\vec k\perp\vec B_0,\ \vec E_1\perp\vec B_0</math> \|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2}{\omega^2}\,~~
	~~\frac{\omega^2-\omega_p^2}{\omega^2-\omega_h^2}<~~/~~math> \|\| X wave~~
	\|-
	~~\| <math>\vec k\\|\vec B_0</math> ([[Polarization (waves)\|right circ~~. ~~pol~~.~~]])\|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2/\omega^2}{1-(\omega_c/\omega)}</math> \|\| R wave (whistler mode)~~
	\|-
	~~\| <math>\vec k\\|\vec B_0</math> ([[Polarization (waves)\|left circ. pol.]])\|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2/\omega^2}{1+(\omega_c/\omega)}</math> \|\| L wave~~
	\|}

	~~==References==~~
	~~{{Reflist\|35em}}~~

	~~==See also==~~
	* [[Appleton-Hartree equation]]
	* [[List of plasma (physics) articles]]

	~~{{DEFAULTSORT:Electromagnetic Electron Wave}}~~
	~~[[Category:Waves in plasmas]~~]

92.224.234.18: /* Line codes for baseband transmission */

2014-01-31T20:12:52Z

Line codes for baseband transmission

← Older revision		Revision as of 22:12, 31 January 2014
Line 1:		Line 1:
	~~Hello. Allow me introduce~~ the ~~writer~~. ~~Her name~~ is ~~Emilia Shroyer but it's not~~ the ~~most female title out~~ there. In ~~her [http:~~//~~richlinked~~.~~com/index~~.~~php?do~~=~~/profile~~-~~32092~~/~~info~~/ over the ~~counter std test~~] ~~expert lifestyle~~ at ~~home~~ [~~http:~~//~~mirim~~.ir/~~index~~.~~php?do~~=/~~profile-699~~/~~info~~/ ~~http~~://~~mirim.ir~~/] ~~std testing she~~ is ~~a payroll clerk but she~~'~~s usually needed her own company~~. ~~Minnesota over~~ the ~~[http:~~//~~Goaskalice~~.~~columbia~~.~~edu/what~~-do-~~genital~~-~~warts-look counter std~~] ~~test is exactly where he's been residing~~ for ~~years. The factor she adores most~~ is ~~physique building and now she is over the counter std test trying~~ to ~~make money with~~ it.<br><br>~~Feel free to surf to my blog post~~ ..~~. [http:~~//~~www~~.~~escuelavirtual~~.~~registraduria.gov.co~~/~~user~~/~~view.php?id~~=~~140944&course~~=~~1 at home std test~~]		In [[plasma physics]], an '''electromagnetic electron wave''' is a [[Waves in plasmas\|wave]] in a [[plasma (physics)\|plasma]] which has a [[magnetic field]] component and in which primarily the [[electron]]s oscillate.

			In an unmagnetized plasma, an electromagnetic electron wave is simply a [[light]] wave modified by the plasma. In a magnetized plasma, there are two modes perpendicular to the field, the O and X modes, and two modes parallel to the field, the R and L waves.

			==Cut-off frequency and critical density==
			In an unmagnetized plasma in the high frequency or low density limit, i.e. for <math>\omega >> (4\pi n_ee^2/m_e)^{1/2}</math>
			or
			<math>n_e << m_e\omega^2\,/\,4\pi e^2</math>,
			the wave speed is the [[speed of light]] in vacuum. As the density increases, the [[phase velocity]] increases and the [[group velocity]] decreases until the '''[[cut-off frequency]]''' where the light frequency is equal to the plasma frequency. This density is known as the '''critical density''' for the [[angular frequency]] ω of that wave and is given by <ref name=Chen>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=116\|edition=2nd\|isbn=0-306-41332-9}}</ref>

			:<math>n_c = \frac{\varepsilon_o\,m_e}{e^2}\,\omega^2</math>.

			If the critical density is exceeded, the plasma is called '''over-dense'''.

			In a magnetized plasma, except for the O wave, the cut-off relationships are more complex.

			==O wave==
			The '''O wave''' is the "ordinary" wave in the sense that its [[dispersion relation]] is the same as that in an unmagnetized plasma. It is [[Plane polarization\|plane polarized]] with
			'''E'''<sub>1</sub> \|\| '''B'''<sub>0</sub>.
			It has a cut-off at the [[plasma frequency]].

			==X wave==
			The '''X wave''' is the "extraordinary" wave because it has a more complicated dispersion relation. It is partly transverse (with '''E'''<sub>1</sub>⊥'''B'''<sub>0</sub>)
			and partly longitudinal. As the density is increased, the phase velocity rises from ''c'' until the cut-off at ω<sub>R</sub> is reached. As the density is further increased, the wave is evanescent until the resonance at the upper hybrid frequency ω<sub>h</sub>. Then it can propagate again until the second cut-off at ω<sub>L</sub>. The cut-off frequencies are given by <ref name=Chen2>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=127\|edition=2nd\|isbn=0-306-41332-9}}</ref>
			:<math>\omega_R = \frac{1}{2}\left[ \omega_c + (\omega_c^2+4\omega_p^2)^{1/2} \right]</math>
			:<math>\omega_L = \frac{1}{2}\left[ -\omega_c + (\omega_c^2+4\omega_p^2)^{1/2} \right]</math>
			where <math>\omega_c</math> is the [[electron cyclotron resonance]] frequency, and <math>\omega_p</math> is the electron [[plasma frequency]].

			==R wave and L wave==
			The '''R wave''' and the '''L wave''' are right-hand and left-hand circularly polarized, respectively. The R wave has a cut-off at ω<sub>R</sub> (hence the designation of this frequency) and a resonance at ω<sub>c</sub>. The L wave has a cut-off at ω<sub>L</sub> and no resonance. R waves at frequencies below ω<sub>c</sub>/2 are also known as '''whistler modes'''. <ref name=Chen3>{{cite book\|last=Chen\|first=Francis\|title=Introduction to Plasma Physics and Controlled Fusion, Volume 1\|publisher=Plenum Publishing Corporation\|year=1984\|page=131\|edition=2nd\|isbn=0-306-41332-9}}</ref>

			==Dispersion relations==
			The [[dispersion relation]] can be written as an expression for the frequency (squared), but it is also common to write it as an expression for the [[index of refraction]] ''ck''/ω (squared).

			{\| class="wikitable"
			\|+ Summary of electromagnetic electron waves
			\|-
			! conditions !! dispersion relation !! name
			\|-
			\| <math>\vec B_0=0</math> \|\| <math>\omega^2=\omega_p^2+k^2c^2</math> \|\| light wave
			\|-
			\| <math>\vec k\perp\vec B_0,\ \vec E_1\\|\vec B_0</math> \|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2}{\omega^2}</math> \|\| O wave
			\|-
			\| <math>\vec k\perp\vec B_0,\ \vec E_1\perp\vec B_0</math> \|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2}{\omega^2}\,
			\frac{\omega^2-\omega_p^2}{\omega^2-\omega_h^2}</math> \|\| X wave
			\|-
			\| <math>\vec k\\|\vec B_0</math> ([[Polarization (waves)\|right circ. pol.]])\|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2/\omega^2}{1-(\omega_c/\omega)}</math> \|\| R wave (whistler mode)
			\|-
			\| <math>\vec k\\|\vec B_0</math> ([[Polarization (waves)\|left circ. pol.]])\|\| <math>\frac{c^2k^2}{\omega^2}=1-\frac{\omega_p^2/\omega^2}{1+(\omega_c/\omega)}</math> \|\| L wave
			\|}

			==References==
			{{Reflist\|35em}}

			==See also==
			* [[Appleton-Hartree equation]]
			* [[List of plasma (physics) articles]]

			{{DEFAULTSORT:Electromagnetic Electron Wave}}
			[[Category:Waves in plasmas]]

en>Wdwd: inter wikilink fix

2012-08-06T18:44:47Z

inter wikilink fix

New page

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