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# Topic: Amplitude modulation

###### In the News (Wed 17 Apr 19)

 Amplitude modulation - Sinusoidal Amplitude Modulation (AM) amplitude modulation (AM): Modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal. Amplitude modulation (AM) is a method of impressing data onto an alternating-current (AC) carrier waveform. Sinusoidal Amplitude Modulation (AM) Sinusoidal Amplitude Modulation (AM) It is instructive to study the modulation of one sinusoid by another. xn--5m4as4o.com /ieua/amplitude-modulation.html   (226 words)

 Multiplying Signals (Amplitude Modulation) Amplitude modulation is an example of the reverse situation, multiplication in the time domain corresponds to convolution in the frequency domain. Modulation is the process of merging two signals to form a third signal with desirable characteristics of both. modulated signal is equal to the audio spectrum shifted to the frequency of the carrier. www.dspguide.com /ch10/5.htm   (729 words)

 Amplitude_Modulation   (Site not responding. Last check: ) Amplitude modulation spectrum of two sine waves, carrier C and modulator M, showing the addition of a pair of sidebands, C + M and C - M, around the carrier. The amplitude of the modulating signal controls the amplitude of the carrier frequency, as well as that of the sidebands, in the resulting spectrum. The strength of the modulation is called the depth of modulation or percentage of modulation and is defined as 100 x (A - B)/(A + B) where A and B are the maximum and minimum peak-to-peak amplitudes of the modulated signal respectively. www.sfu.ca /sonic-studio/handbook/Amplitude_Modulation.html   (301 words)

 Amplitude modulation - Wikipedia, the free encyclopedia Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. This is single-sideband modulation, widely used in amateur radio due to its efficient use of both power and bandwidth. An approach which marries the advantages of low-level modulation with the efficiency of a Class C power amplifier chain is to arrange a feedback system to compensate for the substantial distortion of the AM envelope. en.wikipedia.org /wiki/Amplitude_modulation   (1146 words)

 Amplitude Modulation Amplitude modulation is the simplest way of increasing the frequency of a signal one wishes to transmit. Amplitude modulation consists of multiplying a relatively slowly varying signal by a relatively quickly varying periodic signal. We modulate the first signal to be transmitted by a cosine wave at the carrier frequency, and the second by a sine wave. documents.wolfram.com /applications/signals/AmplitudeModulation.html   (861 words)

 Modulation - DSPWiki Modulation is defined as varying one signal according to changes in a second signal. AM is the less complicated form of modulation, and unsurprisingly involves modulating the amplitude of the carrier signal. When the modulator signal is set to sub-audio frequencies, the increase in its amplitude is heard as an increase in the range of the vibrato caused by the modulator. www.gersic.com /dspwiki/index.php?title=Modulation   (2378 words)

 Optical amplitude modulation modulator - Patent 4086484 In this case the discontinuity is a sinusoidal modulation of a transmission characteristic of the optical fiber material, such as the index of refraction of the optical fiber material, induced by an AM modulated acoustic wave. When the modulated acoustic wave is digital in nature the acoustic wave will be in the form of the presence and absence of pulses of the acoustic wave according to a predetermined digital code to convey a users intelligence into interaction region 2 for interaction with waveguide 1. When the modulated acoustic wave is analog in nature, the acoustic wave is continuous and is amplitude modulated to convey the users intelligence into interaction region 2 for interaction with waveguide 1. www.freepatentsonline.com /4086484.html   (3062 words)

 Definition: amplitude modulation   (Site not responding. Last check: ) amplitude modulation (AM): Modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal. (188) Note: Amplitude modulation implies the modulation of a coherent carrier wave by mixing it in a nonlinear device with the modulating signal to produce discrete upper and lower sidebands, which are the sum and difference frequencies of the carrier and signal. The instantaneous value of the resultant modulated wave is the vector sum of the corresponding instantaneous values of the carrier wave, upper sideband, and lower sideband. www.its.bldrdoc.gov /fs-1037/dir-002/_0277.htm   (133 words)

 Multiplication: amplitude modulation The operation is known as amplitude modulation, because the instantaneous amplitude of the carrier signal varies with the amplitude of the modulation signal. Amplitude modulated long, medium and short wave radio signals are produced by multiplying a radio frequency signal (the carrier wave) with an audio frequency signal superimposed on a constant positive signal (DC component) of at least its own amplitude, the modulation signal. Technically, segment is not `simply' a chunk of the signal, but a window, which is an amplitude modulation of the signal by a value of 0 for all signals outside the window time segment, and by 1 for all values within the window time segment. www.csis.ul.ie /ccmcm/cs5611/acoustics/analysis/node61.html   (392 words)

 MODULATION Modulation may be defined as the process by which a parameter of a high frequency signal termed as carrier, is varied in accordance with the signal to be transmitted. Amplitude modulation (AM) may be categorized as AM with side bands and carrier (AM/DSB), vestigial side band (VSB), double side - band suppressed carrier (DSB/SC), single side - band suppressed carrier (SSB/SC), and independent side - band suppressed carrier (ISB/SC). In angle modulation, the instantaneous angle of a sinusoidal carrier is varied as per the instantaneous amplitude of the modulating signal. www.sem.mosaic-service.com /electron2/modulation.htm   (199 words)

 Measuring modulation   (Site not responding. Last check: ) The average textbook definition of modulation reads: modulation is a process in which the frequency, phase or amplitude of a carrier wave varies in step with the instantaneous value of the modulating signal. The carrier amplitude does not vary with modulation and modulation is usually performed in the oscillator stage at a low level. Modulation measuring equipment has been on the market for a long time, but there are times when a modulation monitor is not available or the monitor's accuracy is in doubt. radiomagonline.com /transmission/radio_measuring_modulation   (927 words)

 Agilent | IQ Modulation In part (a), since the plot of the modulated carrier is relative to the unmodulated carrier, an unmodulated carrier appears as a fixed vector along the positive I axis. Euler's identity is utilized to show that the modulating signal comprises both a positive and negative frequency component; otherwise the modulated carrier would not stay on the I axis. The spectrum of the modulated carrier, shown in the upper left corner of the simulation screen, is that of double-sideband, suppressed-carrier amplitude modulation. education.tm.agilent.com /index.cgi?CONTENT_ID=4   (1081 words)

 ``Classical'' Amplitude Modulation A modulation index, m, is used to control the modulating oscillator amplitude in proportion to the unmodulated carrier oscillator amplitude A. When m = 1, the amplitude of the modulating oscillator is equal to the unmodulated carrier amplitude, which represents 100% modulation. The modulation index controls the amplitude of each of the sideband frequencies by a factor m/2, but does not affect the carrier frequency amplitude. www.music.mcgill.ca /~gary/307/week8/node2.html   (210 words)

 Beats and amplitude modulation   (Site not responding. Last check: ) From what we have seen previously, when the two waves are "in phase" there is constructive interference, meaning the amplitudes of the two waves add to make a wave with twice the amplitude (and hence, four times the intensity) of the individual pure tones. The consequence of the two pure tones alternating between being "in phase" and "out of phase" is evident by the modulation of the amplitude of the superposed wave. Amplitude Modulation (AM) is one of the two basic ways that radio signals are transmitted (the other is frequency modulation or FM). hep.physics.indiana.edu /~rickv/Beats.html   (573 words)

 Modulation Techniques 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. The constant Ka is the amplitude sensitivity of the modulator or the transmitter. If the percentage of modulation is less than or equal to 100%, then the demodulation circuit used to recover the message signal from the incoming AM wave is greatly simplified. www-ee.eng.hawaii.edu /~sasaki/Undergrad/WaveCalc/ZeLi/modulation.html   (651 words)

 Definition: amplitude modulation   (Site not responding. Last check: ) Note: Amplitude modulation implies the modulation of a coherent carrier wave by mixing it in a nonlinear device with the modulating signal to produce discrete upper and lower sidebands, which are the sum and difference frequencies of the carrier and signal. The envelope of the resultant modulated wave is an analog of the modulating signal. The instantaneous value of the resultant modulated wave is the vector sum of the corresponding instantaneous values of the carrier wave, upper sideband, and lower sideband. www.atis.org /tg2k/_amplitude_modulation.html   (154 words)

 Privateline.com: Digital Wireless Basics: Modulation Amplitude modulation, like that still used by Citizens' Band radios, produces a simple, robust wave that doesn't use much spectrum or radio bandwidth. Amplitude modulation means a carrier wave is modulated in proportion to the strength of a signal. We've looked at amplitude modulation, which changes the carrier wave by signal strength, and frequency modulation, which converts the originating signal into cycles. www.privateline.com /PCS/modulation.htm   (2492 words)

 Simon Collings - Principles of Modulation Modulation is the process needed to make a radio frequency wave carry a signal that conveys some sort of information (or intelligence). A variety of modulation techniques can be heard on the air, but you will need a receiver with a BFO or SSB detector to resolve many of them. This is combined amplitude and phase modulation to produce a high speed digital symbol stream which makes best use of the available bandwidth. www.scnt01426.pwp.blueyonder.co.uk /Articles/Modulation/Modulation.htm   (551 words)

 Amplitude modulation Summary Amplitude modulation was a great improvement in radio transmission, but it has limitations; interference caused by the earth's ionosphere is a big problem. Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. An approach which marries the advantages of low-level modulation with the efficiency of a Class C power amplifier chain is to arrange a feedback system to compensate for the substantial distortion of the AM envelope. www.bookrags.com /Amplitude_modulation   (1573 words)

 BOSS-FM: MODULATION CHAPTER-1 The peak amplitude of the wave is equal to the radius of the circle, and the peak-to-peak amplitude is equal to the diameter of the circle. In amplitude modulation, the amplitude of the carrier is varied in proportion to the amplitude of the modulating wave. The percentage of modulation of an a-m wave is the percentage ratio of the peak-to-peak amplitude of the modulating voltage to the peak-to-peak amplitude of the carrier. www.geocities.com /SoHo/Study/8903/fmod1.html   (4685 words)

 Pulse-amplitude modulation - Wikipedia, the free encyclopedia Pulse-amplitude modulation, acronym PAM, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. Demodulation is performed by detecting the amplitude level of the carrier at every symbol period. Pulse-amplitude modulation is now rarely used, having been largely superseded by pulse-code modulation, and, more recently, by pulse-position modulation. en.wikipedia.org /wiki/Pulse-amplitude_modulation   (386 words)

 Agilent Technologies | Educator's Corner - Resource Guide for Engineering Educators | Amplitude Modulation Amplitude modulation was the original method used for transmitting audio signals over radio frequency waves. Where Wc is the carrier frequency, Wm is the modulation frequency and m is the modulation index. A modulation index of 1 means that the modulation is just as big as the carrier, ie., 100% modulation. www.educatorscorner.com /index.cgi?CONTENT_ID=2485   (292 words)

 Types of Synthesis - The Sonic Spot The modulation signal can be used as an envelope which is applied to the carrier signal to determine the audio signals amplitude over time. The modulation signal can be also be used to quickly cycle the carrier signal's amplitude to form two additional frequencies known as sidebands, forming harmonic or non-harmonic sounds. When the modulation signal is used to quickly cycle the carrier signal's amplitude, like AM synthesis it forms two additional sidebands, but the carrier signal is cancelled out and disappears. www.sonicspot.com /guide/synthesistypes.html   (983 words)

 Agilent Technologies | Test & Measurement In amplitude modulation the amplitude of a slowly varying signal is impressed onto the amplitude of a rapidly varying signal. The mathematical description of the modulation of a sinusoidal carrier by another sinusoid is given in the formula below where wc is the carrier frequency, wm is the modulation frequency, and m is the degree of modulation. The two sideband components have equal amplitudes which are proportional to the amplitude of the modulating signal. contact.tm.agilent.com /Agilent/tmo/an-150-1/classes/liveAM.html   (313 words)

 Types of Modulation (AM, FM, PM) In Amplitude modulation (AM), the information signal is mixed with the carrier signal in such a way as to cause the AMPLITUDE of the carrier to vary at the frequency of the information signal. As the voltage of the modulating signal increases in the positive direction from A to B, the frequency of the carrier is increased in proportion to the to the modulating voltage. The modulated carrier wave is lagging the carrier wave when the modulating frequency is positive. cbdd.wsu.edu /kewlcontent/cdoutput/TR502/page21.htm   (272 words)

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