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Topic: Carrier wave


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  T-carrier - Wikipedia, the free encyclopedia
The basic unit of the T-carrier system is the DS0, which has a transmission rate of 64 kbit/s, and is commonly used for one voice circuit.
Originally the T1 format carried 24 pulse-code modulated, time-division multiplexed speech signals each encoded in 64 kbit/s streams, leaving 8 kbit/s of framing information which facilitates the synchronization and demultiplexing at the receiver.
Technically a DS1 is the data carried on a T1 circuit, and likewise for a DS3 and a T3, but the terms are almost always used interchangeably.
en.wikipedia.org /wiki/T-carrier   (914 words)

  
 Carrier wave - Wikipedia, the free encyclopedia
A carrier wave, or carrier is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted.
This carrier wave is usually of much higher frequency than the modulating signal (the signal which contains the information).
Carrier waves are used when transmitting radio signals to a radio receiver.
en.wikipedia.org /wiki/Carrier_wave   (263 words)

  
 Encyclopedia: Carrier wave   (Site not responding. Last check: 2007-10-20)
In the case of Single-sideband modulation (SSB) the carrier is suppressed and must be reintroduced at the receiver by a beat frequency oscillator (BFO.) Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave.
In trigonometry, an ideal sine wave is a waveform whose graph is identical to the generalized sine function y = Asin[ω(x − α)] + C, where A is the amplitude, ω is the angular frequency (2π/P where P is the wavelength), α is the phase shift, and C is the...
In telecommunication, a carrier system (loosely, a synonym with carrier) is a multichannel telecommunications system in which a number of individual circuits (data, voice, or combination thereof) are multiplexed for transmission between nodes of a network.
www.nationmaster.com /encyclopedia/Carrier-wave   (1047 words)

  
 [No title]   (Site not responding. Last check: 2007-10-20)
The signals modulate the carrier wave and the carrier waves are transmitted to the radio path using a radio channel.
The means 203 amplify the carrier wave in such a manner that the carrier wave propagates far enough from the base station 200 to the subscriber terminals 100.
Several generated carrier waves are combined in the means 204, whereby the signals generated by several trans- mitters 201 are connected to the same antenna 206.
www.wipo.int /cgi-pct/guest/getbykey5?KEY=98/19465.980507&ELEMENT_SET=DECL   (2124 words)

  
 Modulation Techniques   (Site not responding. Last check: 2007-10-20)
In amplitude modulation, the circuit or the modulator combines the carrier wave (Fig 1) and the message signal (Fig 2) to form a modulated wave (Fig 3) that is a carrier wave with change in amplitude.
Carrier Wave - A cosine wave with amplitude 3 and frequency 100 Hz.
This is the same for a carrier wave except its frequency is very large when compare to the frequency of the message signal.
www-ee.eng.hawaii.edu /~sasaki/Undergrad/WaveCalc/ZeLi/modulation.html   (651 words)

  
 Amateur Radio application of Frequency Modulation
Phase Modulation (PM) is a similar system where the phase of the carrier wave is varied in sympathy with the voltage of the modulating signal, and as in frequency modulation, the amplitude of a carrier is held constant.
Now Phase and Frequency are related, an incremental frequency shift of the carrier wave frequency causes a continuing change in phase (wrt the original carrier), the rate of change of phase is proportional to the frequency shift.
Note the large number of sidebands and the carrier (in the centre of the diagram) is near to zero at this level of modulation (modulation index is 2.5).
www.vk1od.net /FM/FM.htm   (3127 words)

  
 United States Patent Application: 0040121739
Thus, when a wireless channel having a reception carrier frequency in the vicinity of the frequency of the electromagnetic-interference wave is being received by the cellular phone, the electromagnetic-interference wave interferes with communication in the wireless channel, causing degradation in the reception sensitivity.
As is apparent from equation (5), the reception carrier frequency of the cellular phone falls in the vicinity of the frequency of the EMI wave generated by the contactless-IC-card reader writer.
The second carrier frequency is controlled so that the frequency of an electromagnetic-interference wave that is generated together with the second electromagnetic wave does not fall within a predetermined frequency range with which reception sensitivity to the first electromagnetic wave is degraded.
appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040121739".PGNR.&OS=DN/20040121739&RS=DN/20040121739   (5861 words)

  
 carrier wave --  Encyclopædia Britannica
Most familiar are surface waves on water, but both sound and light travel as wavelike disturbances, and the motion of all subatomic particles exhibits wavelike properties.
This is represented graphically in the as a wave form, in which the range of electrical values (voltage or current) is plotted vertically and time is plotted horizontally.
A train of waves used for broadcasting at a particular frequency is called a carrier wave.
www.britannica.com /eb/article-9020505   (707 words)

  
 Untitled Document   (Site not responding. Last check: 2007-10-20)
In frequency modulation we leave the amplitude of the radio frequency EM carrier wave constant and vary the frequency of the carrier wave in proportion the signal from the microphone.
The frequency of the carrier wave is less susceptible to change than its amplitude, so the receiver reproduces the signal more accurately.
Waves will bend easily around obstacles comparable to or smaller than a wavelength, but the bending is less obvious around obstacles that are large compared to a wavelength (see figure below).
www.vuw.ac.nz /scps-students/tech102/lectures/week9/9Mon_and_Wednesday/Summary_9_Weds.htm   (1957 words)

  
 X-Man Al's Marvel Super Heroes Classic RPG Web Source - Database of Powers - Travel Powers - Carrier Wave   (Site not responding. Last check: 2007-10-20)
The carrier wave is temporarily solid and visible.
For example, a sonic carrier wave is limited to SX speed.
Carrier waves can be affected by the appropriate Energy Emission and Control Powers.
www.angelfire.com /rpg2/xmanalb/CarrierWave.html   (279 words)

  
 Digital Transmission -- Digital Modulation and Fourier Series   (Site not responding. Last check: 2007-10-20)
Both the carrier and the encoded signal were assumed to be simple sine waves and it was in understanding the complex modulated signal that was actually transmitted that we used a simple special case of a sum of sine waves to describe a complex wave.
In the case of an audio signal described by a simple sine wave, we saw that the transmitted signal consisted of a pair of sine waves whose frequencies fell above and below the frequency of the carrier wave by an amount equal to the frequency of the audio signal.
The differences between the frequencies of the sine waves that compose a modulated signal and the carrier frequency are determined by the frequencies of the sine wave that compose the original signal.
www.cs.williams.edu /~cs105/s01/text/ch3/DigitalTrans_17.html   (2881 words)

  
 Frequency Modulation   (Site not responding. Last check: 2007-10-20)
A Frequency Modulated wave is a sine wave with a periodically varying instantaneous frequency and a constant amplitude.
If this were an FM radio transmission, the carrier frequency would be the station you tune to, and you would hear a pure audio tone at the modulation frequency, with a loudness derived from the modulation depth.
The stationary fl wave is the strong carrier frequency; the weaker red and blue ones are lower and higher frequencies.
www.chemistry.bnl.gov /gpmd/old-pages/FM.HTML   (574 words)

  
 Communications Glossary   (Site not responding. Last check: 2007-10-20)
Type of modulation in which the amplitude of a carrier wave is caused to vary in accordance with the amplitude variations of the information to be transmitted.
The upper sideband corresponds to the sum of the carrier and modulating frequencies, whereas the lower sideband corresponds to the difference between the carrier and modulating frequencies.
Modulation in which the frequency of the carrier is caused to vary in an amount proportional to the amplitude of the modulating wave.
research.umbc.edu /~cellis3/glossary.html   (5989 words)

  
 [No title]   (Site not responding. Last check: 2007-10-20)
The 250 kc transmitting frequency is called the carrier wave because it may be thought of as carrying the audio.
The lower wave is the modulated carrier wave and 75 cycles are visible.
When the modulating wave is at zero (the point where it begins and ends) the carrier wave is at its middle or unmodulated value.
www.angelfire.com /electronic/funwithtubes/How_AM_Works.html   (641 words)

  
 MY PRACTICE WEB PAGE   (Site not responding. Last check: 2007-10-20)
The carrier signal amplitude (height) is altered, or modulated, to reflect changes in the audio signals amplitude.
Inpuse-coded modulation (pcm) the intelligence signal converts the carrier into a series of constant-amplitude pulses spaced in such a manner that the described inteloligence is contained in coded form.
The phase of a carrier wave is varied in response to the vibrations of the sound source in phase modulation (pm).
www.mbhs.edu /~jkaluta/fall2000/809904ranold-tv.htm   (387 words)

  
 Last modified   (Site not responding. Last check: 2007-10-20)
The carrier wave in pulse modulation is a series of pulses all the same amplitude, width and equal spacing.
In this diagram, the carrier wave is represented by white, the signal wave by fl.
A radio wave's frequency relates to the length of the wave, or the distance the wave is from peak to peak as it travels through the air.
www.gordon.army.mil /ocos/rdiv/FORKIDS/radowork.htm   (766 words)

  
 Modulators and Hybrids
The function is expressed as the sum of the carrier, and two sidebands, one the difference of the carrier and signal frequencies, and one the sum, called the lower and upper sidebands.
This sideband is produced with the aid of the carrier at the transmitting station, and is demodulated at the receiving station with the aid of a copy of the carrier.
Traditionally, an AM wave was created by changing the gain of an RF amplifier in time with the modulating signal, or by the use of a nonlinear amplifier.
www.du.edu /~etuttle/electron/elect61.htm   (3177 words)

  
 Carrier Wave Documentation
Carrier Wave was designed to allow interprocess communication between any application and a pool of pre-started programs.  For this document and the initial development the focus has been on communication between a web server and a pool of Progress batch clients, however, keep in mind that many other combinations are possible.
Carrier Wave was written in perl and therefore should be able to run on most popular platforms provided that the suitable perl modules are available.  It has currently been successfully run on the following platforms:
Progress Note:  I had trouble running Carrier Wave on NT with Progress 8.1A.  The problems seemed to involve the “input-output through” command.  Installing 8.2A fixed the trouble, I have not spent the time to go back and trouble shoot.  At this point versions of Progress prior to 8.2 may not work.
home.austin.rr.com /a3/cw_doc.html   (1718 words)

  
 Medcyclopaedia - Carrier wave
The information is modulated onto the carrier wave so that its amplitude and phase vary as a function of time.
In MR imaging the carrier wave is the radiofrequency wave oscillating at the Larmor frequency which carries the signals containing the tissue information out of the body.
The same principle also applies in ultrasonography: the sound wave radiated into the patient is the carrier wave which, as it is reflected or altered by Doppler shift (see Doppler ultrasound), is modulated thus containing information on tissue structure and properties.
www.medcyclopaedia.com /library/topics/volume_i/c/CARRIER_WAVE.aspx   (161 words)

  
 Re: what are the physics principles in televisions that relate to waves?
A great many carrier waves of different frequencies are being generated by radio and TV stations; electronic circuits known as "filters" allow a receiver of electromagnetic waves to select the particular frequency that the user wants.
Because the receiver has an easier time detecting the carrier wave if that wave is transmitted continually, the information is transmitted in the form of a sequence of higher-power and lower-power waves:.
The overall shape of each wave in the carrier wave is very smoothly wavelike, but the wave preceding or following it may have rather greater or lesser amplitude.
www.madsci.org /posts/archives/jun2000/960135604.Ph.r.html   (2634 words)

  
 Privateline.com: Digital Wireless Basics: Modulation
Amplitude modulation means a carrier wave is modulated in proportion to the strength of a signal.
For more on carrier waves: what they are, what they do, and why we need them, you may want to read my wireless history series from the start.
A carrier wave stays roughly on the same frequency, give or take, no matter if it is modulated by amplitude, frequency, or phase.
www.privateline.com /PCS/modulation.htm   (2492 words)

  
 Sum and Difference Frequencies, Sidebands and Bandwidth
The process of superimposing the "electrical image" of the sound information on the carrier wave is called modulation, and there are two commonly used schemes: amplitude modulation (AM) and frequency modulation (FM).
Either form of modulation produces frequencies which are the sum and the difference of the carrier and modulation frequencies - these frequencies are sometimes called sidebands.
But when you superimpose a signal on the carrier by AM or FM, you produce sidebands at the sum and difference of the carrier and modulation frequencies.
hyperphysics.phy-astr.gsu.edu /hbase/audio/sumdif.html   (455 words)

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