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Topic: Carrier frequencies

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  Amplitude modulation - Wikipedia, the free encyclopedia
The output of this process is a signal with the same frequency as the carrier but with peaks and troughs that vary in proportion to the strength of the modulating signal.
Its output is a signal at the carrier frequency, with peaks that trace the amplitude of the unmodulated signal.
In practice, a capacitor is used to undo the DC shift introduced by the transmitter and to eliminate the carrier frequency by connecting the signal peaks.
en.wikipedia.org /wiki/Amplitude_modulation   (1251 words)

 Carrier wave - Wikipedia, the free encyclopedia
Carrier waves are used when transmitting radio signals to a radio receiver.
Frequency modulation (FM) and amplitude modulation (AM) signals are both transmitted with the help of carrier frequencies.
The frequency for a given radio station is actually the carrier wave's center frequency.
en.wikipedia.org /wiki/Carrier_wave   (230 words)

 Digital Synthesis
These sidebands are symmetrically spaced about the frequency of the carrier[3], and the size of the spaces is equal to the frequency of the modulator.
If the frequencies of the carrier and modulator are not rationally related, the tone will have a less definite pitch, and will have a rich sound.
By applying an envelope function to the amount of modulation or the frequencies of carrier and modulator, sounds can be produced that have a life and excitement far beyond that available with the older synthesis methods.
arts.ucsc.edu /ems/music/tech_background/TE-17/teces_17.html   (876 words)

 Communications Glossary   (Site not responding. Last check: 2007-11-07)
Frequencies resulting from the combination of two or more different frequencies in a non-linear device, such as an amplifier, numerically equal to the sum and the difference of these frequencies.
Modulation in which the frequency of the carrier is caused to vary in an amount proportional to the amplitude of the modulating wave.
The frequency of the carrier is shifted rapidly between two frequencies, known as the mark and space frequencies.
userpages.umbc.edu /~cellis3/glossary.html   (5989 words)

 Time and Frequency from A to Z   (Site not responding. Last check: 2007-11-07)
When the calibration is finished it should be possible to state the estimated time offset and/or frequency offset of the device under test with respect to the standard, as well as the measurement uncertainty.
The base frequency of a transmitted electromagnetic pulse or wave on which information can be imposed by varying the signal strength, varying the base frequency, varying the wave phase, or other means.
If the carrier frequency is derived from a cesium oscillator, the received signal can be used to calibrate other frequency sources.
www.boulder.nist.gov /timefreq/general/enc-c.htm   (872 words)

 Radio Broadcast Signals
The carrier frequency is directly modulated with the sum of the left and right channel audio signals.
An electromagnetic carrier wave which is carrying a signal by means of amplitude modulation or frequency modulation can transfer that signal to a carrier of different frequency by means of a process called heterodyning.
This process produces a beat frequency equal to the difference between the frequencies, and this difference frequency constitutes a third carrier which will be modulated by the original signal.
hyperphysics.phy-astr.gsu.edu /hbase/audio/radio.html   (438 words)

 AM transmitter principles
The frequency of 95 kilohertz, for example, is heterodyned with the frequency of 100 kilohertz and the sum and difference frequencies are again produced.
However, when the carrier and sidebands are combined in a single impedance and viewed simultaneously with an oscilloscope, the resultant waveform appears as shown in figure 1-39.
Carrier assignments start at 540 kilohertz and continue in a succession of 10-kilohertz increments until the upper limit of the broadcast band is reached.
www.tpub.com /neets/book12/48k.htm   (1417 words)

 Frequency Modulation
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)

 Electromagnetic Spectrum
Carrier frequencies of 540 to 1600 kHz are assigned at 10 kHz intervals.
The frequencies from the top end of the AM band to the bottom of the VHF television band are generally called the "short wave" range, a historical term.
The RF frequency range around 40-50 MHz is important as the proton resonance frequency range used in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).
hyperphysics.phy-astr.gsu.edu /hbase/ems2.html#c4   (585 words)

 Carrier wave -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-07)
This carrier wave is usually of much higher (The number of occurrences within a given time period (usually 1 second)) frequency than the modulating signal (the signal which contains the information).
Carrier waves are used when transmitting (A communication system based on broadcasting electromagnetic waves) radio signals to a radio receiver.
The frequency for a given radio station is actually the carrier wave's (Click link for more info and facts about center frequency) center frequency.
www.absoluteastronomy.com /encyclopedia/c/ca/carrier_wave.htm   (230 words)

 [No title]
The ratio of carrier to the peak of the distortion is defined as the CTB.
Carrier to Noise is the ratio of the carrier to the noise in some specified channel.
The carrier is used as a reference and the noise is usually measured using the “Noise Marker” of the spectrum analyzer set to a quite spot in the band.
www.matrixtest.com /FAQsonDistortion.htm   (2330 words)

 Superheterodyne Receivers
These are beat frequencies (normally the beat frequency is associated with the lower side-band, the difference between the two).
It is in fact, the local oscillator (a operating at radar frequencies) of the superheterodyne radar receiver that makes your radar detector detectable by the police (in VA for example, where the use of radar detectors are illegal).
Frequently, the receiver bandwidth is some fraction of the carrier frequency.
www.fas.org /man/dod-101/navy/docs/es310/superhet.htm   (1244 words)

 MSN Encarta - Print Preview - Television
This transmitting antenna radiates the carrier waves in all directions, and the waves travel through the air to antennas connected to television sets or relay stations.
The amplitude of one carrier wave is modulated to carry the video signal (amplitude modulation, or AM) and the frequency of another wave is modulated to carry the audio signal (frequency modulation, or FM).
The frequency of carrier waves is measured in hertz (Hz), which is equal to the number of wave peaks that pass by a point every second.
encarta.msn.com /text_761559903___32/Television.html   (1140 words)

 Primer: Sampling Oscilloscope Techniques
Distortion occurring at the third harmonic, the sums and differences of three fundamental frequencies, or the combination of the second harmonic of one signal and the fundamental of another, is called third-order distortion.
Disable the carrier for the channel-under-test at the headend.
In that case, either the modulator's unmodulated carrier level must be increased to equal its peak output when modulated or a substitution carrier, equal in amplitude to the peak of the modulated carrier, must be used.
www.tek.com /Measurement/App_Notes/2EW_10598/advanced.html   (10556 words)

 [No title]
Frequency modulation refers to periodic changes in the frequency of the carrier wave.
Audio frequencies from a source that fall into the range of 200 Hz - 5 kHz are used to amplitude modulate a carrier wave with frequency in the range 535-1605 kHz.
For AM broadcasting, the rate at which the amplitude of the carrier changes is proportional to the frequency of the modulating (audio) signal, while the degree to which the carrier wave amplitude changes is related to the amplitude of the modulating signal.
abacus.bates.edu /~jsmedley/phys104/chapt8.htm   (772 words)

 8.6: FM Systems
This disadvantage is also reflected in the fact that the FM function requires a wider range of frequencies near the carrier frequency to achieve the modulation over that required with AM systems.
The difference between the upper frequency of the required range, which is fc+fm and the lower frequency of the range, which is fc-fm, is called the bandwidth requirements of the system.
Thus, an AM system broadcasting audio frequencies up to 10 kilohertz on a carrier frequency of 1 megahertz would require frequencies after modulation of from 990,000 hertz to 1,010,000 hertz for a band width of 20,000 hertz.
campus.murraystate.edu /tsm/tsm118/Ch8/Ch8_6/ch8_6.htm   (822 words)

 Pad versus Plasma tube Rife Instruments
Audio frequencies will not broadcast; therefore, they were modulated upon the carrier frequency so that they would penetrate the body where they would devitalize microorganisms.
Audio frequencies without the carrier will only work in the connective tissues but with a carrier frequency the audio frequencies can enter the cell where the virus is located.
In order to have a carrier frequency a second function generator will have to be obtained or you will have to purchase one that has a built in carrier frequency.
www.emfsafe.com /rife/padvplasma.htm   (4611 words)

 [No title]   (Site not responding. Last check: 2007-11-07)
The 250 kc transmitting frequency is called the carrier wave because it may be thought of as carrying the audio.
Connecting the peaks is done by using a capacitor to charge up to the peak value and discharge through a resistor just fast enough to follow the modulating frequency but not so fast as to cause a large variation at the carrier frequency.
The frequencies chosen for this drawing are fairly close together to make it possible to see the individual cycles on your computer screen.
www.angelfire.com /electronic/funwithtubes/How_AM_Works.html   (641 words)

 Articles - Transmitter   (Site not responding. Last check: 2007-11-07)
The modulator is the device which piggybacks (or modulates) the signal information onto the carrier frequency, which is then broadcast.
In the early days of radio engineering, radio frequency energy was generated using arcs or mechanical alternators (of which a rare example survives at the SAQ transmitter in Grimeton, Sweden).
Often the transmitter frequency is not the frequency produced by the oscillator, but one of its harmonics.
www.zgrey.com /articles/Transmitter   (1680 words)

 [No title]
Specifically, the Commission stated that an existing private operational fixed licensee operating on frequencies shared with common carriers, i.e., frequencies in the 4, 6, 10, 11, 18, 31, and 38 GHz bands, may elect common carrier status simply by notifying the Commission of its change in status by filing the appropriate form and tariff information.
We find that Westinghouse has failed to demonstrate that the underlying purpose of the rules will not be served or would be frustrated by their application in its particular case, and that grant of the waiver is in the public interest.
In addition, Westinghouse did not submit any information that indicates that it cannot transmit common carrier traffic at another higher-frequency band where such communications are permitted, or that migration to another band would result in degradation of service quality that would be unacceptable for the communications carried on the system.
www.fcc.gov /Bureaus/Wireless/Orders/2000/da000393.txt   (2063 words)

 Cystic fibrosis carrier frequencies in populations of African origin -- Padoa et al. 36 (1): 41 -- Journal of Medical ...
carrying this mutation was identified by means of the PCR assay.
A mutation carrier frequency in unaffected African fls is 1 in 128 (9/1152) (table 1).
A mutation carrier frequency is 1 in 91.
www.jmedgenet.com /cgi/content/full/36/1/41   (2575 words)

 EDN Access--06.05.97 Modulator draws just 5 mA at 2.7V
The traditional method for producing SSB signals is to modulate a carrier and then filter the output to remove the unwanted sideband and carrier frequencies.
No filtering is necessary to suppress the carrier and sideband frequencies because frequency cancellation is inherent in modulation.
Measurements of the circuit operating with an oscillator frequency of 142 MHz and a carrier of 71 MHz indicate carrier suppression of ­27 dB, which is 8 dB short of the typical data-sheet performance specification.
www.edn.com /archives/1997/060597/12di_02.htm   (497 words)

 NIST Calibration Services: Tests of PM/AM Noise Measurement Systems
The calibrated PM or AM noise is typically constant with Fourier frequency offset to +0.1 dB out to 3 % of the carrier frequency.
Given two or more oscillators, synthesizers, frequency multiplier/dividers, or amplifiers, relative phase noise can be measured with low uncertainty and the frequency for the measurement is not as restrictive as above.
Also, the 1 pulse per second output of atomic frequency standards can be measured with a standard uncertainty of 0.5 ns given an adequately defined pulse.
ts.nist.gov /ts/htdocs/230/233/calibrations/time_freq/pm_am_noise.htm   (659 words)

 NPS GPS Support Facility Website   (Site not responding. Last check: 2007-11-07)
It provides reliable, repeatable information that is unaffected by rough terrain and bad weather, and is highly resistant to multipath errors and interference.The satellites broadcast on two carrier frequencies in the L-band of the electromagnetic spectrum.
On these carrier frequencies are broadcast codes, much like a radio or television station broadcast information on their channels (frequencies).
There are two basic types of SPS receivers, those that use the broadcasted code to do their positioning (code-phase) and those that do carrier phase measurements (carrier-phase).
www.sep.nps.gov /gis/gps/feature.html   (266 words)

 Cable TV Channel Frequencies
Cable channels operating on frequencies used in the aeronautical radiocommunications bands 118-137, 225-328.6 and 335.4-400 MHz are required to be offset by 12.5 kHz from 25 kHz-spaced channels [FCC Rules section 76.612 (a)].
Cable channels operating on frequencies used in the aeronautical radiocommunications bands 108-118 and 328.6-335.4 MHz are required to be offset by 25 kHz from 50 kHz-spaced channels [FCC Rules section 76.612 (b)].
The frequency of over-the-air broadcast channels 2 through 69 is specified in FCC Rule 73.603.
www.jneuhaus.com /fccindex/cablech.html   (395 words)

 Holistic Health Encyclopedia - B   (Site not responding. Last check: 2007-11-07)
But it wasn't until the early 1970's that neuroscientists confirmed that with the use of sound it is possible to stimulate the brain to move to or through any of the four main brainwave states.
But by using these lower carriers, we have created a stronger version of that alpha state; a version which saturates the nervous system with stimulus which, in turn, produces improved functioning.
This herb is frequently used in preparations for increasing human stamina and physical endurance.
www.findhealer.com /glossary/B.php3   (10216 words)

 EE113L, Fall 95, Experiment 3   (Site not responding. Last check: 2007-11-07)
, the input signal frequency F and the carrier frequency Fc.
Find the one frequency that is the original and filter out the rest.) Do this question graphically using the relationships derived previously.
You may assume that the signal frequency F is relatively small compared to the sampling frequency.
www.icsl.ucla.edu /~spapl/course/exp3r.html   (298 words)

 Determine your cellphone - carrier frequency range - Criterion Cellular   (Site not responding. Last check: 2007-11-07)
They may have changed their names several times but not their frequencies.
If your carrier has been around for that long, chances are that they are using 800MHz.
Too many times the customer service folks at the carriers blurt out the wrong answer and end up causing you to purchase the wrong frequency antenna (which defeats the whole purpose!) Another possibility is to call the local cellular shop and ask them.
cellular-amplifier.com /tutorials/findfrequencies.html   (499 words)

 Rockwell Automation - Electronic Application Note (E-Note) D-152
Higher drive carrier frequencies lower the audible noise emitted from a motor.
The a-weighted 2,000 center frequency octave value of a motor running at 2 kHz is 75.13 compared to 66.17 at 4 kHz.
Maximum carrier frequency is a major factor in setting this turn-on time, it is not user selectable.
www.reliance.com /prodserv/standriv/hvac/d152.htm   (699 words)

 Carrier frequencies (%) for major haemoglobin disordersin selected countries of the SEA Region
Carrier frequencies (%) for major haemoglobin disordersin selected countries of the SEA Region
This page must be viewed with IE4 or above, and with Active Scripting enabled.
Table 63: Carrier frequencies (%) for major haemoglobin disordersin selected countries of the SEA Region
w3.whosea.org /eip/tab63.htm   (108 words)

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