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1240:
997:
977:
59:
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4064:
2022:
4074:
4053:
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2459:
767:, providing a frequency and phase reference to extract the modulation from the sidebands. In some modulation systems based on AM, a lower transmitter power is required through partial or total elimination of the carrier component, however receivers for these signals are more complex because they must provide a precise carrier frequency reference signal (usually as shifted to the
33:
2923:
2167:. Even (analog) television, with a (largely) suppressed lower sideband, includes sufficient carrier power for use of envelope detection. But for communications systems where both transmitters and receivers can be optimized, suppression of both one sideband and the carrier represent a net advantage and are frequently employed.
2175:
and would return to full power during periods of high modulation levels. This has the effect of reducing the overall power demand of the transmitter and is most effective on speech type programmes. Various trade names are used for its implementation by the transmitter manufacturers from the late 80's
2333:
are the modulation amplitude and carrier amplitude, respectively; the modulation amplitude is the peak (positive or negative) change in the RF amplitude from its unmodulated value. Modulation index is normally expressed as a percentage, and may be displayed on a meter connected to an AM transmitter.
2150:
Another improvement over standard AM is obtained through reduction or suppression of the carrier component of the modulated spectrum. In figure 2 this is the spike in between the sidebands; even with full (100%) sine wave modulation, the power in the carrier component is twice that in the sidebands,
1222:
formulated the first mathematical description of amplitude modulation, showing that a signal and carrier frequency combined in a nonlinear device creates a sideband on both sides of the carrier frequency. Passing the modulated signal through another nonlinear device can extract the original baseband
1172:
to make an AM transmitter. Modulation did not have to be done at the output but could be applied to the signal before the final amplifier tube, so the microphone or other audio source didn't have to modulate a high-power radio signal. Wartime research greatly advanced the art of AM modulation, and
2591:
obtained a patent for synthesizing a modulated high-power carrier wave from a set of digitally selected low-power amplifiers, running in phase at the same carrier frequency. The input signal is sampled by a conventional audio analog-to-digital converter (ADC), and fed to a digital exciter, which
2116:
The short-term spectrum of modulation, changing as it would for a human voice for instance, the frequency content (horizontal axis) may be plotted as a function of time (vertical axis), as in figure 3. It can again be seen that as the modulation frequency content varies, an upper sideband is
1049:
Fessenden was a significant figure in the development of AM radio. He was one of the first researchers to realize, from experiments like the above, that the existing technology for producing radio waves, the spark transmitter, was not usable for amplitude modulation, and that a new kind of
2436:
referred to as "AM" even though it generates an identical RF waveform as standard AM as long as the modulation index is below 100%. Such systems more often attempt a radical reduction of the carrier level compared to the sidebands (where the useful information is present) to the point of
762:
AM is also inefficient in power usage; at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the original information being transmitted (voice, video, data, etc.). However its presence provides a simple means of demodulation using
835:
A simple form of amplitude modulation is the transmission of speech signals from a traditional analog telephone set using a common battery local loop. The direct current provided by the central office battery is a carrier with a frequency of 0 Hz. It is modulated by a microphone
2420:. In that case, negative excursions beyond zero entail a reversal of the carrier phase, as shown in the third waveform below. This cannot be produced using the efficient high-level (output stage) modulation techniques (see below) which are widely used especially in high power
2518:
Older designs (for broadcast and amateur radio) also generate AM by controlling the gain of the transmitter's final amplifier (generally class-C, for efficiency). The following types are for vacuum tube transmitters (but similar options are available with transistors):
1993:
1135:
inserted directly in the antenna or ground wire; its varying resistance varied the current to the antenna. The limited power handling ability of the microphone severely limited the power of the first radiotelephones; many of the microphones were water-cooled.
1046:, over a distance of one mile (1.6 km) at Cobb Island, Maryland, US. His first transmitted words were, "Hello. One, two, three, four. Is it snowing where you are, Mr. Thiessen?". The words were barely intelligible above the background buzz of the spark.
1059:, was needed. This was a radical idea at the time, because experts believed the impulsive spark was necessary to produce radio frequency waves, and Fessenden was ridiculed. He invented and helped develop one of the first continuous wave transmitters – the
1722:
2536:(high-value inductor). The AM modulation tube plate is fed through the same inductor, so the modulator tube diverts current from the RF amplifier. The choke acts as a constant current source in the audio range. This system has a low power efficiency.
2142:
techniques; it thus may be viewed as spectrally inefficient. Within a frequency band, only half as many transmissions (or "channels") can thus be accommodated. For this reason analog television employs a variant of single-sideband (known as
2389:, it varies by 100% as shown in the illustration below it. With 100% modulation the wave amplitude sometimes reaches zero, and this represents full modulation using standard AM and is often a target (in order to obtain the highest possible
1486:
840:) in the telephone set according to the acoustic signal from the speaker. The result is a varying amplitude direct current, whose AC-component is the speech signal extracted at the central office for transmission to another subscriber.
2170:
A technique used widely in broadcast AM transmitters is an application of the
Hapburg carrier, first proposed in the 1930s but impractical with the technology then available. During periods of low modulation the carrier power would be
1004:
AM radio transmitters, built by
Meissner in 1913 with an early triode tube by Robert von Lieben. He used it in a historic 36 km (24 mi) voice transmission from Berlin to Nauen, Germany. Compare its small size with above transmitter.
2467:
Modulation circuit designs may be classified as low- or high-level (depending on whether they modulate in a low-power domain—followed by amplification for transmission—or in the high-power domain of the transmitted signal).
2568:
Two tubes are operated in parallel, but partially out of phase with each other. As they are differentially phase modulated their combined amplitude is greater or smaller. Efficiency is good and distortion low when properly
1009:
Amplitude modulation was used in experiments of multiplex telegraph and telephone transmission in the late 1800s. However, the practical development of this technology is identified with the period between 1900 and 1920 of
865:
of the audio aids intelligibility. However it is absolutely undesired for music or normal broadcast programming, where a faithful reproduction of the original program, including its varying modulation levels, is expected.
2441:
where the carrier is (ideally) reduced to zero. In all such cases the term "modulation index" loses its value as it refers to the ratio of the modulation amplitude to a rather small (or zero) remaining carrier amplitude.
2286:
2480:(DSP). With DSP many types of AM are possible with software control (including DSB with carrier, SSB suppressed-carrier and independent sideband, or ISB). Calculated digital samples are converted to voltages with a
848:
An additional function provided by the carrier in standard AM, but which is lost in either single or double-sideband suppressed-carrier transmission, is that it provides an amplitude reference. In the receiver, the
2121:
the carrier frequency, and the same content mirror-imaged in the lower sideband below the carrier frequency. At all times, the carrier itself remains constant, and of greater power than the total sideband power.
2134:") signal, since the upper and lower sidebands around the carrier frequency each have a bandwidth as wide as the highest modulating frequency. Although the bandwidth of an AM signal is narrower than one using
750:
where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast is not favored for music and
1173:
after the war the availability of cheap tubes sparked a great increase in the number of radio stations experimenting with AM transmission of news or music. The vacuum tube was responsible for the rise of
2462:
Anode (plate) modulation. A tetrode's plate and screen grid voltage is modulated via an audio transformer. The resistor R1 sets the grid bias; both the input and output are tuned circuits with inductive
2542:
The operating bias and gain of the final RF amplifier can be controlled by varying the voltage of the control grid. This method requires little audio power, but care must be taken to reduce distortion.
599:
1531:
2163:
and regeneration of the carrier frequency. For that reason, standard AM continues to be widely used, especially in broadcast transmission, to allow for the use of inexpensive receivers using
1768:
2577:
A highly efficient high voltage power supply is applied to the tube plate. The output voltage of this supply is varied at an audio rate to follow the program. This system was pioneered by
2151:
yet it carries no unique information. Thus there is a great advantage in efficiency in reducing or totally suppressing the carrier, either in conjunction with elimination of one sideband (
861:
circuit which holds the AGC level for a second or more following such peaks, in between syllables or short pauses in the program. This is very acceptable for communications radios, where
853:(AGC) responds to the carrier so that the reproduced audio level stays in a fixed proportion to the original modulation. On the other hand, with suppressed-carrier transmissions there is
701:
For example, in AM radio communication, a continuous wave radio-frequency signal has its amplitude modulated by an audio waveform before transmission. The message signal determines the
1131:
transmitter (arc converter), invented in 1903. The modifications necessary to transmit AM were clumsy and resulted in very low quality audio. Modulation was usually accomplished by a
2488:
to the desired frequency and power level (linear amplification must be used to prevent modulation distortion). This low-level method for AM is used in many
Amateur Radio transceivers.
1512:> 1 then overmodulation occurs and reconstruction of message signal from the transmitted signal would lead in loss of original signal. Amplitude modulation results when the carrier
1330:
799:
broadcasting, standard AM with the full carrier allows for reception using inexpensive receivers. The broadcaster absorbs the extra power cost to greatly increase potential audience.
4657:
2409:
circuit (especially for voice communications) in order to still approach 100% modulation for maximum intelligibility above the noise. Such circuits are sometimes referred to as a
1526:
857:
transmitted power during pauses in the modulation, so the AGC must respond to peaks of the transmitted power during peaks in the modulation. This typically involves a so-called
2090:
may be considered to consist of an equal mix of positive and negative frequency components, as shown in the top of figure 2. One can view the sidebands as that modulation
1364:
672:) is constant and the second term of the equation has a functional relationship to the modulating message signal. Angle modulation provides two methods of modulation,
658:
2859:
2184:
The AM modulation index is a measure based on the ratio of the modulation excursions of the RF signal to the level of the unmodulated carrier. It is thus defined as:
2086:. The collection of the former frequencies above the carrier frequency is known as the upper sideband, and those below constitute the lower sideband. The modulation
629:
400:
AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with
2387:
2361:
1063:, with which he made what is considered the first AM public entertainment broadcast on Christmas Eve, 1906. He also discovered the principle on which AM is based,
2592:
modulates overall transmitter output power by switching a series of low-power solid-state RF amplifiers on and off. The combined output drives the antenna system.
2331:
2310:
2552:, which reduces voltage according to the modulation signal. It is difficult to approach 100-percent modulation while maintaining low distortion with this system.
2526:
In plate modulation, the plate voltage of the RF amplifier is modulated with the audio signal. The audio power requirement is 50 percent of the RF-carrier power.
2560:
One tube provides the power under carrier conditions and another operates only for positive modulation peaks. Overall efficiency is good, and distortion is low.
791:
and other voice communications because it has power and bandwidth efficiency (cutting the RF bandwidth in half compared to standard AM). On the other hand, in
3328:
723:
to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called "double-sideband amplitude modulation" (DSBAM).
787:(SSB-SC), leading to the characteristic "Donald Duck" sound from such receivers when slightly detuned. Single-sideband AM is nevertheless used widely in
424:
uses bandpass filters to eliminate one of the sidebands and possibly the carrier signal, which improves the ratio of message power to total transmission
2190:
2130:
The RF bandwidth of an AM transmission (refer to figure 2, but only considering positive frequencies) is twice the bandwidth of the modulating (or "
2653:
2438:
2397:, causes a standard AM modulator (see below) to fail, as the negative excursions of the wave envelope cannot become less than zero, resulting in
2159:). While these suppressed carrier transmissions are efficient in terms of transmitter power, they require more sophisticated receivers employing
2152:
930:
784:
776:
341:
2432:
is incapable of properly demodulating such a signal. Rather, synchronous detection is required. Thus double-sideband transmission is generally
2684:
2674:"Father Landell de Moura : Radio Broadcasting Pioneer : FABIO S. FLOSI : UNICAMP – University of Campinas, State of São Paulo"
2112:
of an AM voice broadcast shows the two sidebands (green) on either side of the carrier (red) with time proceeding in the vertical direction.
823:
where it is known as continuous wave (CW) operation, even though the transmission is not strictly "continuous". A more complex form of AM,
4120:
4036:
4008:
4003:
3028:
2417:
1200:
were developing the other large application for AM: sending multiple telephone calls through a single wire by modulating them on separate
4422:
4172:
2041:
can be expressed as the sum of a set of sine waves of various frequencies, amplitudes, and phases. Carrying out the multiplication of
305:
1087:(1906) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem.
1030:, pulses of radio waves that declined to zero, and sounded like a buzz in receivers. In effect they were already amplitude modulated.
694:
The modulating message signal may be analog in nature, or it may be a digital signal, in which case the technique is generally called
2963:
4461:
4030:
2632:
2484:, typically at a frequency less than the desired RF-output frequency. The analog signal must then be shifted in frequency and
523:
428:, reduces power handling requirements of line repeaters, and permits better bandwidth utilization of the transmission medium.
4432:
4025:
4015:
3995:
3797:
2834:
2809:
2784:
1231:
transatlantic telephone service beginning 7 January 1927. After WW-II, it was developed for military aircraft communication.
875:
2851:
17:
3162:
2990:
4481:
4087:
4020:
3866:
2363:, carrier amplitude varies by 50% above (and below) its unmodulated level, as is shown in the first waveform, below. For
1988:{\displaystyle y(t)=A\sin(2\pi f_{c}t)+{\frac {1}{2}}Am\leftt+\phi \right)+\sin \left(2\pi \leftt-\phi \right)\right].\,}
334:
250:
2996:
1223:
signal. His analysis also showed that only one sideband was necessary to transmit the audio signal, and Carson patented
726:
A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects
3792:
2416:
However it is possible to talk about a modulation index exceeding 100%, without introducing distortion, in the case of
2156:
819:
are represented by the presence or absence of a carrier. On–off keying is likewise used by radio amateurs to transmit
3886:
2984:
2949:
2918:, "Amplitude modulation using digitally selected carrier amplifiers", published 1986-04-01, assigned to
502:
which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal,
229:
4113:
3671:
3219:
3021:
123:
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224:
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163:
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90:
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represents the time-varying amplitude of the sinusoidal carrier wave and the cosine-term is the carrier at its
327:
1014:
transmission, that is, the effort to send audio signals by radio waves. The first radio transmitters, called
4442:
3802:
720:
1717:{\displaystyle {\begin{aligned}y(t)&=\leftc(t)\\&=\leftA\sin \left(2\pi f_{c}t\right)\end{aligned}}}
742:
improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to
4369:
4077:
3838:
3735:
3278:
3073:
3045:
909:
772:
731:
4667:
4106:
4067:
3574:
3014:
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827:
is now more commonly used with digital data, while making more efficient use of the available bandwidth.
506:
the information. At the receiving station, the message signal is extracted from the modulated carrier by
128:
4640:
4609:
4354:
4264:
3926:
3848:
3787:
3494:
2974:
2940:
Newkirk, David and
Karlquist, Rick (2004). Mixers, modulators and demodulators. In D. G. Reed (ed.),
1224:
1042:
on 23 December 1900 using a spark gap transmitter with a specially designed high frequency 10 kHz
919:
906:
421:
280:
100:
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3698:
3659:
3504:
3404:
3333:
3266:
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2477:
2406:
862:
153:
2673:
1227:(SSB) on 1 December 1915. This advanced variant of amplitude modulation was adopted by AT&T for
1079:
or "liquid baretter", in 1902. Other radio detectors invented for wireless telegraphy, such as the
4057:
3299:
3234:
3187:
3147:
2643:
2147:, somewhat of a compromise in terms of bandwidth) in order to reduce the required channel spacing.
984:
from 1906. The carrier wave is generated by 6 electric arcs in the vertical tubes, connected to a
401:
290:
173:
1751:
660:. This description directly provides the two major groups of modulation, amplitude modulation and
109:
4619:
4518:
4471:
4379:
3896:
3881:
3725:
3676:
3599:
3499:
3177:
3063:
3058:
2172:
1481:{\displaystyle m(t)=M\cos \left(2\pi f_{m}t+\phi \right)=Am\cos \left(2\pi f_{m}t+\phi \right)\,}
1124:
1060:
187:
66:
2424:
transmitters. Rather, a special modulator produces such a waveform at a low level followed by a
2033:
is usually more complex than a single sine wave, as treated above. However, by the principle of
373:(signal strength) of the wave is varied in proportion to that of the message signal, such as an
4513:
4427:
4269:
3818:
3604:
3419:
3364:
3359:
3172:
3137:
2749:
Innovation and the
Communications Revolution: From the Victorian Pioneers to Broadband Internet
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AM may also be generated at a low level, using analog methods described in the next section.
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2034:
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2340:
2135:
940:
743:
673:
420:), because the standard method produces sidebands on either side of the carrier frequency.
386:
365:
technique used in electronic communication, most commonly for transmitting messages with a
143:
80:
2449:
Figure 4: Modulation depth. In the diagram, the unmodulated carrier has an amplitude of 1.
8:
4349:
4220:
3644:
3584:
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3305:
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3088:
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1019:
452:
168:
4098:
2393:) but mustn't be exceeded. Increasing the modulating signal beyond that point, known as
1336:
The message signal, such as an audio signal that is used for modulating the carrier, is
4486:
3871:
3828:
3759:
3629:
3559:
3534:
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and has a number of variations, all of which achieve high efficiency and sound quality.
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or DSB-RC) to use in the demodulation process. Even with the carrier eliminated in
708:
703:
691:), of the equation has a functional relationship to the modulating message signal.
677:
661:
394:
378:
275:
270:
95:
85:
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A simple form of digital amplitude modulation which can be used for transmitting
488:
436:
432:
425:
210:
976:
755:
broadcasting, but rather for voice communications and broadcasts (sports, news,
4214:
3742:
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3549:
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3182:
3157:
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1201:
1043:
1011:
491:
409:
37:
2613:, can provide better-quality demodulation with additional circuit complexity.
2401:("clipping") of the received modulation. Transmitters typically incorporate a
2281:{\displaystyle m={\frac {\mathrm {peak\ value\ of\ } m(t)}{A}}={\frac {M}{A}}}
4686:
4589:
4314:
4194:
4133:
3891:
3664:
3654:
3569:
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1747:) thus corresponds to the top graph (labelled "50% Modulation") in figure 4.
1149:
1112:
1080:
985:
981:
788:
752:
747:
727:
683:
In amplitude modulation, the angle term is held constant and the first term,
444:
440:
390:
1026:. They could not transmit audio because the carrier consisted of strings of
58:
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2049:
as above, the result consists of a sum of sine waves. Again, the carrier
1145:
1128:
1120:
1027:
1001:
792:
780:
472:
2852:"RF and Microwave Power Amplifier and Transmitter Technologies – Part 2"
1038:
The first AM transmission was made by
Canadian-born American researcher
711:, amplitude modulation produces a signal with power concentrated at the
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4452:
4154:
3974:
3681:
3379:
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1998:
Therefore, the modulated signal has three components: the carrier wave
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Early experiments in AM radio transmission, conducted by
Fessenden,
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2131:
2003:
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medium. Amplitude modulation was virtually the only type used for
716:
480:
47:
2898:
National
Association of Broadcasters Engineering Handbook, 11th Ed
2800:
Silver, Ward, ed. (2011). "Ch. 15 DSP and
Software Radio Design".
412:
experiments in 1900. This original form of AM is sometimes called
4319:
4274:
4228:
3949:
3934:
3152:
2648:
2402:
1022:, using pulses of the carrier wave to spell out text messages in
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2006:
with frequencies slightly above and below the carrier frequency
431:
AM remains in use in many forms of communication in addition to
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4238:
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Pulse-width modulation (PWM) or pulse-duration modulation (PDM)
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One of the crude pre-vacuum tube AM transmitters, a
Telefunken
2021:
32:
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4259:
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3964:
3901:
3209:
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2476:
In modern radio systems, modulated signals are generated via
2458:
2410:
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265:
2993:
including related topics of modulators, demodulators, etc...
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494:
with an information-bearing modulation waveform, such as an
3906:
734:
in equal proportion to the signal. Increasing the received
2025:
Figure 2: Double-sided spectra of baseband and AM signals.
4128:
2772:
2716:, 2nd Edition, Bell Center for Technical Education (1977)
824:
460:
815:, the simplest form of amplitude-shift keying, in which
594:{\displaystyle m(t)=A(t)\cdot \cos(\omega t+\phi (t))\,}
2895:
2829:(Eighty-eighth ed.). American Radio Relay League.
2804:(Eighty-eighth ed.). American Radio Relay League.
898:
a full-carrier – the basic amplitude modulation scheme
2053:
is present unchanged, but each frequency component of
2752:. Inst. of Electrical Engineers. pp. 59, 61–62.
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2343:
2318:
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2193:
1771:
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988:. Modulation is done by the large carbon microphone
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617:
526:
2944:(81st ed.), pp. 15.1–15.36. Newington: ARRL.
1144:
The 1912 discovery of the amplifying ability of the
878:(ITU) designated the types of amplitude modulation:
36:
Figure 1: An audio signal (top) may be carried by a
965:(a submode of any of the above ITU Emission Modes)
2997:Analog Modulation online interactive demonstration
2601:The simplest form of AM demodulator consists of a
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2355:
2325:
2304:
2280:
1987:
1762:) can be shown to be the sum of three sine waves:
1716:
1480:
1324:
652:
623:
593:
2849:
2825:Silver, Ward, ed. (2011). "Ch. 14 Transceivers".
2548:The screen-grid bias may be controlled through a
2515:stages, modulated by varying the supply voltage.
2117:generated according to those frequencies shifted
4684:
2125:
1115:, were hampered by the lack of a technology for
2439:double-sideband suppressed-carrier transmission
2428:. What's more, a standard AM receiver using an
2153:single-sideband suppressed-carrier transmission
785:single-sideband suppressed-carrier transmission
777:double-sideband suppressed-carrier transmission
4114:
3022:
2727:Engineering and Operations in the Bell System
2101:as depicted at the bottom right of figure 2.
771:) from a greatly reduced "pilot" carrier (in
335:
2532:RF amplifier plate voltage is fed through a
2418:double-sideband reduced-carrier transmission
517:may be described by the following equation:
4037:Global telecommunications regulation bodies
2850:Frederick H. Raab; et al. (May 2003).
2094:having simply been shifted in frequency by
1508:is always positive for undermodulation. If
779:, carrier regeneration is possible using a
513:In general form, a modulation process of a
4121:
4107:
4073:
3029:
3015:
2942:The ARRL Handbook for Radio Communications
2827:The ARRL Handbook for Radio Communications
2802:The ARRL Handbook for Radio Communications
2710:Telecommunication Transmission Engineering
2405:circuit to avoid overmodulation, and/or a
1152:, solved these problems. The vacuum tube
1127:, developed 1906–1910, or versions of the
1119:. The first practical continuous wave AM
342:
328:
2881:Laurence Gray and Richard Graham (1961).
2322:
2301:
2002:which is unchanged in frequency, and two
1984:
1477:
1325:{\displaystyle c(t)=A\sin(2\pi f_{c}t)\,}
1321:
1123:were based on either the huge, expensive
631:, and the instantaneous phase deviation
590:
2494:
2457:
2444:
2103:
2020:
1516:is multiplied by the positive quantity
1238:
995:
975:
869:
31:
2910:
2596:
2471:
14:
4685:
3036:
2824:
2799:
2779:. Technical Publications. p. 36.
2741:
2739:
2737:
2735:
2633:Amplitude modulation signalling system
843:
4499:
4102:
3010:
2529:Heising (constant-current) modulation
2453:
1739:= 0.5 the amplitude modulated signal
1732:
1090:
876:International Telecommunication Union
707:of the transmitted waveform. In the
385:of the carrier wave is varied, as in
4083:
2773:Atul P. Godse; U. A. Bakshi (2009).
2745:
2155:) or with both sidebands remaining (
1243:Illustration of amplitude modulation
1192:At the same time as AM radio began,
414:double-sideband amplitude modulation
2732:
2690:from the original on 9 October 2022
2609:. Another type of demodulator, the
2545:Clamp tube (screen grid) modulation
2179:
1500:is the amplitude of modulation. If
1033:
830:
27:Radio modulation via wave amplitude
24:
4500:
2240:
2237:
2231:
2228:
2225:
2222:
2219:
2213:
2210:
2207:
2204:
2157:double sideband suppressed carrier
1213:
1177:around 1920, the first electronic
931:single-sideband suppressed-carrier
25:
4704:
2985:Federation of American Scientists
2956:
2862:from the original on 6 March 2016
2064:has two sidebands at frequencies
664:. In angle modulation, the term
4655:
4082:
4072:
4063:
4062:
4051:
3672:Free-space optical communication
2896:Cavell, Garrison C. Ed. (2018).
1067:, and invented one of the first
377:. This technique contrasts with
57:
2934:
2904:
2889:
2507:) are based on high-efficiency
1207:frequency division multiplexing
1139:
1050:transmitter, one that produced
825:quadrature amplitude modulation
802:
738:, say, by a factor of 10 (a 10
487:means varying some aspect of a
369:. In amplitude modulation, the
4595:Error detection and correction
2969:Wolfram Demonstrations Project
2885:. McGraw-Hill. pp. 141ff.
2874:
2843:
2818:
2793:
2766:
2719:
2702:
2666:
2605:which is configured to act as
2256:
2250:
1818:
1796:
1781:
1775:
1599:
1593:
1576:
1570:
1543:
1537:
1496:is the amplitude sensitivity,
1377:
1371:
1318:
1296:
1281:
1275:
647:
641:
587:
584:
578:
563:
551:
545:
536:
530:
13:
1:
2991:Amplitude Modulation tutorial
2900:. Routledge. pp. 1099ff.
2659:
2138:(FM), it is twice as wide as
2126:Power and spectrum efficiency
1018:, transmitted information by
498:which represents sound, or a
466:
4058:Telecommunication portal
3839:Telecommunications equipment
773:reduced-carrier transmission
732:electromagnetic interference
719:. Each sideband is equal in
7:
4668:Comparison of radio systems
3575:Alexander Stepanovich Popov
2616:
2482:digital-to-analog converter
2029:A useful modulation signal
2016:
1752:prosthaphaeresis identities
1234:
10:
4709:
4641:International broadcasting
4610:FM extended band in Brazil
3279:Telecommunications history
1225:single-sideband modulation
1189:began after World War II.
971:
422:Single-sideband modulation
251:Capacity-approaching codes
4649:
4628:
4567:
4527:
4506:
4495:
4451:
4408:
4378:
4342:
4307:
4300:
4252:
4181:
4150:
4143:
4046:
3988:
3925:
3887:Public Switched Telephone
3847:
3811:
3768:
3709:
3699:telecommunication circuit
3660:Fiber-optic communication
3643:
3405:Francis Blake (telephone)
3352:
3200:Optical telecommunication
3044:
2776:Communication Engineering
2478:digital signal processing
783:. This does not work for
3798:Orbital angular-momentum
3235:Satellite communications
3074:Communications satellite
2644:Types of radio emissions
2503:(such as those used for
1735:, discussed below. With
1164:, was a cheap source of
781:Costas phase-locked loop
653:{\displaystyle \phi (t)}
402:Roberto Landell de Moura
4620:Shortwave relay station
4519:Audio signal processing
3677:Molecular communication
3500:Gardiner Greene Hubbard
3329:Undersea telegraph line
3064:Cable protection system
2539:Control grid modulation
1344:), and has a frequency
1125:Alexanderson alternator
1061:Alexanderson alternator
963:compressor and expander
859:fast attack, slow decay
624:{\displaystyle \omega }
515:sinusoidal carrier wave
188:Hierarchical modulation
40:using AM or FM methods.
4693:Radio modulation modes
4514:Audio data compression
3819:Communication protocol
3605:Charles Sumner Tainter
3420:Walter Houser Brattain
3365:Edwin Howard Armstrong
3173:Information revolution
2464:
2450:
2383:
2357:
2327:
2306:
2282:
2113:
2026:
1989:
1718:
1482:
1326:
1244:
1156:, invented in 1912 by
1148:, invented in 1906 by
1016:spark gap transmitters
1006:
993:
851:automatic gain control
769:intermediate frequency
696:amplitude-shift keying
654:
625:
595:
381:, in which either the
41:
4615:Multipath propagation
4438:MPEG-1 Audio Layer II
4308:Frequency allocations
4183:Frequency allocations
3793:Polarization-division
3525:Narinder Singh Kapany
3490:Erna Schneider Hoover
3410:Jagadish Chandra Bose
3390:Alexander Graham Bell
3121:online video platform
3001:Google Colab Platform
2983:, an introduction by
2856:High Frequency Design
2564:Outphasing modulation
2495:High-level generation
2461:
2448:
2391:signal-to-noise ratio
2384:
2382:{\displaystyle m=1.0}
2358:
2356:{\displaystyle m=0.5}
2328:
2307:
2283:
2161:synchronous detection
2107:
2035:Fourier decomposition
2024:
1990:
1719:
1483:
1327:
1242:
1077:electrolytic detector
999:
992:in the antenna lead.
979:
870:ITU type designations
736:signal-to-noise ratio
655:
626:
596:
35:
4568:Technical (emission)
3635:Vladimir K. Zworykin
3595:Almon Brown Strowger
3565:Charles Grafton Page
3220:Prepaid mobile phone
3148:Electrical telegraph
2981:Amplitude Modulation
2975:Amplitude Modulation
2964:Amplitude Modulation
2597:Demodulation methods
2472:Low-level generation
2367:
2341:
2316:
2295:
2191:
2136:frequency modulation
1769:
1731:is identical to the
1727:In this simple case
1527:
1365:
1269:
1204:frequencies, called
1168:and could be easily
1075:and receive AM, the
941:independent-sideband
744:frequency modulation
674:frequency modulation
635:
615:
524:
387:frequency modulation
355:Amplitude modulation
18:Amplitude Modulation
3585:Johann Philipp Reis
3344:Wireless revolution
3306:The Telephone Cases
3163:Hydraulic telegraph
2746:Bray, John (2002).
2326:{\displaystyle A\,}
2305:{\displaystyle M\,}
1220:John Renshaw Carson
1194:telephone companies
1154:feedback oscillator
1020:wireless telegraphy
844:Amplitude reference
453:citizens band radio
3783:Frequency-division
3760:Telephone exchange
3630:Charles Wheatstone
3560:Jun-ichi Nishizawa
3535:Innocenzo Manzetti
3470:Reginald Fessenden
3205:Optical telegraphy
3038:Telecommunications
2883:Radio Transmitters
2589:Harris Corporation
2556:Doherty modulation
2486:linearly amplified
2465:
2454:Modulation methods
2451:
2379:
2353:
2323:
2302:
2278:
2165:envelope detection
2145:vestigial sideband
2114:
2027:
1985:
1714:
1712:
1478:
1351:, much lower than
1322:
1247:The carrier wave (
1245:
1183:radio broadcasting
1179:mass communication
1162:Alexander Meissner
1091:Early technologies
1040:Reginald Fessenden
1007:
994:
952:vestigial-sideband
765:envelope detection
650:
621:
591:
477:telecommunications
455:, and in computer
449:VHF aircraft radio
406:Reginald Fessenden
110:Digital modulation
42:
4680:
4679:
4676:
4675:
4600:FM broadcast band
4507:Technical (audio)
4404:
4403:
4296:
4295:
4096:
4095:
3834:Store and forward
3829:Data transmission
3743:Network switching
3694:Transmission line
3540:Guglielmo Marconi
3505:Internet pioneers
3370:Mohamed M. Atalla
3339:Whistled language
2967:by Jakub Serych,
2836:978-0-87259-096-0
2811:978-0-87259-096-0
2786:978-81-8431-089-4
2639:Modulation sphere
2607:envelope detector
2430:envelope detector
2276:
2263:
2245:
2236:
2218:
1832:
1583:
1133:carbon microphone
1000:One of the first
969:
968:
715:and two adjacent
713:carrier frequency
610:angular frequency
352:
351:
67:Analog modulation
16:(Redirected from
4700:
4662:Radio portal
4660:
4659:
4658:
4636:History of radio
4580:AM expanded band
4497:
4496:
4380:Commercial radio
4305:
4304:
4148:
4147:
4123:
4116:
4109:
4100:
4099:
4086:
4085:
4076:
4075:
4066:
4065:
4056:
4055:
4054:
3927:Notable networks
3917:Wireless network
3857:Cellular network
3849:Types of network
3824:Computer network
3711:Network topology
3625:Thomas A. Watson
3480:Oliver Heaviside
3465:Philo Farnsworth
3440:Daniel Davis Jr.
3415:Charles Bourseul
3375:John Logie Baird
3084:Data compression
3079:Computer network
3031:
3024:
3017:
3008:
3007:
2999:using Python in
2928:
2927:
2926:
2922:
2908:
2902:
2901:
2893:
2887:
2886:
2878:
2872:
2871:
2869:
2867:
2847:
2841:
2840:
2822:
2816:
2815:
2797:
2791:
2790:
2770:
2764:
2763:
2743:
2730:
2723:
2717:
2706:
2700:
2699:
2697:
2695:
2689:
2678:
2670:
2611:product detector
2523:Plate modulation
2426:linear amplifier
2388:
2386:
2385:
2380:
2362:
2360:
2359:
2354:
2332:
2330:
2329:
2324:
2311:
2309:
2308:
2303:
2287:
2285:
2284:
2279:
2277:
2269:
2264:
2259:
2246:
2243:
2234:
2216:
2201:
2180:Modulation index
1994:
1992:
1991:
1986:
1980:
1976:
1975:
1971:
1961:
1957:
1956:
1955:
1943:
1942:
1908:
1904:
1894:
1890:
1889:
1888:
1876:
1875:
1833:
1825:
1814:
1813:
1733:modulation index
1723:
1721:
1720:
1715:
1713:
1709:
1705:
1701:
1700:
1671:
1667:
1666:
1662:
1652:
1651:
1605:
1589:
1585:
1584:
1579:
1565:
1487:
1485:
1484:
1479:
1476:
1472:
1462:
1461:
1426:
1422:
1412:
1411:
1331:
1329:
1328:
1323:
1314:
1313:
1262:is expressed by
1166:continuous waves
1105:Quirino Majorana
1097:Valdemar Poulsen
1085:crystal detector
1056:continuous waves
1034:Continuous waves
881:
880:
831:Analog telephony
709:frequency domain
678:phase modulation
662:angle modulation
659:
657:
656:
651:
630:
628:
627:
622:
600:
598:
597:
592:
395:phase modulation
379:angle modulation
344:
337:
330:
61:
44:
43:
21:
4708:
4707:
4703:
4702:
4701:
4699:
4698:
4697:
4683:
4682:
4681:
4672:
4656:
4654:
4645:
4624:
4605:FM broadcasting
4575:AM broadcasting
4563:
4523:
4502:
4491:
4447:
4400:
4374:
4343:Digital systems
4338:
4323:
4292:
4253:Digital systems
4248:
4177:
4139:
4127:
4097:
4092:
4052:
4050:
4042:
3984:
3921:
3843:
3807:
3764:
3713:
3705:
3646:
3639:
3545:Robert Metcalfe
3400:Tim Berners-Lee
3348:
3168:Information Age
3040:
3035:
2959:
2937:
2932:
2931:
2924:
2916:Swanson, Hilmer
2909:
2905:
2894:
2890:
2879:
2875:
2865:
2863:
2848:
2844:
2837:
2823:
2819:
2812:
2798:
2794:
2787:
2771:
2767:
2760:
2744:
2733:
2724:
2720:
2707:
2703:
2693:
2691:
2687:
2681:Aminharadio.com
2676:
2672:
2671:
2667:
2662:
2628:Shortwave radio
2619:
2599:
2584:Digital methods
2513:power amplifier
2505:AM broadcasting
2497:
2474:
2456:
2368:
2365:
2364:
2342:
2339:
2338:
2317:
2314:
2313:
2296:
2293:
2292:
2268:
2203:
2202:
2200:
2192:
2189:
2188:
2182:
2140:single-sideband
2128:
2099:
2084:
2080:
2073:
2069:
2062:
2019:
2011:
1951:
1947:
1938:
1934:
1933:
1929:
1922:
1918:
1884:
1880:
1871:
1867:
1866:
1862:
1855:
1851:
1844:
1840:
1824:
1809:
1805:
1770:
1767:
1766:
1711:
1710:
1696:
1692:
1685:
1681:
1647:
1643:
1636:
1632:
1616:
1612:
1603:
1602:
1566:
1564:
1557:
1553:
1546:
1530:
1528:
1525:
1524:
1457:
1453:
1446:
1442:
1407:
1403:
1396:
1392:
1366:
1363:
1362:
1356:
1349:
1309:
1305:
1270:
1267:
1266:
1256:
1251:) of frequency
1237:
1216:
1214:Single-sideband
1187:FM broadcasting
1175:AM broadcasting
1158:Edwin Armstrong
1142:
1109:Charles Herrold
1093:
1083:(1904) and the
1036:
982:arc transmitter
974:
920:single-sideband
910:reduced-carrier
907:single-sideband
896:double-sideband
872:
846:
833:
805:
636:
633:
632:
616:
613:
612:
525:
522:
521:
489:continuous wave
469:
459:in the form of
437:shortwave radio
433:AM broadcasting
348:
211:Spread spectrum
28:
23:
22:
15:
12:
11:
5:
4706:
4696:
4695:
4678:
4677:
4674:
4673:
4671:
4670:
4665:
4650:
4647:
4646:
4644:
4643:
4638:
4632:
4630:
4626:
4625:
4623:
4622:
4617:
4612:
4607:
4602:
4597:
4592:
4587:
4582:
4577:
4571:
4569:
4565:
4564:
4562:
4561:
4556:
4554:Kahn-Hazeltine
4551:
4546:
4541:
4535:
4533:
4525:
4524:
4522:
4521:
4516:
4510:
4508:
4504:
4503:
4501:Related topics
4493:
4492:
4490:
4489:
4484:
4479:
4474:
4469:
4464:
4458:
4456:
4449:
4448:
4446:
4445:
4440:
4435:
4430:
4425:
4420:
4414:
4412:
4406:
4405:
4402:
4401:
4399:
4398:
4397:
4396:
4385:
4383:
4376:
4375:
4373:
4372:
4367:
4362:
4357:
4352:
4346:
4344:
4340:
4339:
4337:
4336:
4331:
4326:
4321:
4317:
4311:
4309:
4302:
4298:
4297:
4294:
4293:
4291:
4290:
4285:
4282:
4277:
4272:
4267:
4262:
4256:
4254:
4250:
4249:
4247:
4246:
4236:
4218:
4208:
4198:
4187:
4185:
4179:
4178:
4176:
4175:
4170:
4165:
4159:
4157:
4145:
4141:
4140:
4126:
4125:
4118:
4111:
4103:
4094:
4093:
4091:
4090:
4080:
4070:
4060:
4047:
4044:
4043:
4041:
4040:
4033:
4028:
4023:
4018:
4013:
4012:
4011:
4006:
3998:
3992:
3990:
3986:
3985:
3983:
3982:
3977:
3972:
3967:
3962:
3957:
3952:
3947:
3942:
3937:
3931:
3929:
3923:
3922:
3920:
3919:
3914:
3909:
3904:
3899:
3894:
3889:
3884:
3879:
3874:
3869:
3864:
3859:
3853:
3851:
3845:
3844:
3842:
3841:
3836:
3831:
3826:
3821:
3815:
3813:
3809:
3808:
3806:
3805:
3800:
3795:
3790:
3785:
3780:
3778:Space-division
3774:
3772:
3766:
3765:
3763:
3762:
3757:
3756:
3755:
3750:
3740:
3739:
3738:
3728:
3723:
3717:
3715:
3707:
3706:
3704:
3703:
3702:
3701:
3691:
3690:
3689:
3679:
3674:
3669:
3668:
3667:
3657:
3651:
3649:
3641:
3640:
3638:
3637:
3632:
3627:
3622:
3617:
3615:Camille Tissot
3612:
3607:
3602:
3597:
3592:
3590:Claude Shannon
3587:
3582:
3580:Tivadar Puskás
3577:
3572:
3567:
3562:
3557:
3552:
3550:Antonio Meucci
3547:
3542:
3537:
3532:
3527:
3522:
3520:Charles K. Kao
3517:
3512:
3507:
3502:
3497:
3495:Harold Hopkins
3492:
3487:
3482:
3477:
3472:
3467:
3462:
3457:
3452:
3447:
3442:
3437:
3432:
3427:
3422:
3417:
3412:
3407:
3402:
3397:
3395:Emile Berliner
3392:
3387:
3382:
3377:
3372:
3367:
3362:
3356:
3354:
3350:
3349:
3347:
3346:
3341:
3336:
3334:Videotelephony
3331:
3326:
3325:
3324:
3319:
3309:
3302:
3297:
3291:
3286:
3281:
3276:
3271:
3270:
3269:
3264:
3259:
3249:
3248:
3247:
3237:
3232:
3230:Radiotelephone
3227:
3222:
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3116:Internet video
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3019:
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2977:, by S Sastry.
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2957:External links
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2499:High-power AM
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2395:overmodulation
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2108:Figure 3: The
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2082:
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2071:
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2060:
2018:
2015:
2009:
1996:
1995:
1983:
1979:
1974:
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1277:
1274:
1258:and amplitude
1254:
1236:
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1215:
1212:
1141:
1138:
1092:
1089:
1035:
1032:
1012:radiotelephone
973:
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967:
966:
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938:
934:
933:
928:
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917:
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912:
904:
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893:
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871:
868:
845:
842:
832:
829:
817:ones and zeros
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649:
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589:
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583:
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556:
553:
550:
547:
544:
541:
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535:
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492:carrier signal
468:
465:
445:two-way radios
410:radiotelephone
350:
349:
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339:
332:
324:
321:
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106:
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104:
103:
98:
93:
88:
83:
78:
70:
69:
63:
62:
54:
53:
38:carrier signal
26:
9:
6:
4:
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2:
4705:
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4134:digital audio
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3803:Code-division
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3788:Time-division
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3722:
3719:
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3692:
3688:
3685:
3684:
3683:
3680:
3678:
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3665:optical fiber
3663:
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3655:Coaxial cable
3653:
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3648:
3642:
3636:
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3570:Radia Perlman
3568:
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3478:
3476:
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3468:
3466:
3463:
3461:
3460:Lee de Forest
3458:
3456:
3455:Thomas Edison
3453:
3451:
3448:
3446:
3445:Donald Davies
3443:
3441:
3438:
3436:
3433:
3431:
3430:Claude Chappe
3428:
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3408:
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3308:
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3301:
3298:
3295:
3292:
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3287:
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3280:
3277:
3275:
3274:Smoke signals
3272:
3268:
3265:
3263:
3260:
3258:
3255:
3254:
3253:
3252:Semiconductor
3250:
3246:
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3241:
3238:
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3149:
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3144:
3141:
3139:
3136:
3132:
3129:
3127:
3124:
3122:
3119:
3117:
3114:
3113:
3112:
3111:Digital media
3109:
3105:
3102:
3100:
3097:
3095:
3092:
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3087:
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3082:
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3018:
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3009:
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2950:0-87259-196-4
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2907:
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2686:
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2100:
2093:
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2063:
2056:
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2048:
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2032:
2023:
2014:
2012:
2005:
2001:
1981:
1977:
1972:
1968:
1965:
1962:
1958:
1952:
1948:
1944:
1939:
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1930:
1926:
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1199:
1195:
1190:
1188:
1184:
1180:
1176:
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1167:
1163:
1159:
1155:
1151:
1150:Lee de Forest
1147:
1137:
1134:
1130:
1126:
1122:
1118:
1117:amplification
1114:
1113:Lee de Forest
1110:
1106:
1102:
1098:
1088:
1086:
1082:
1081:Fleming valve
1078:
1074:
1070:
1066:
1062:
1058:
1057:
1053:
1047:
1045:
1041:
1031:
1029:
1025:
1021:
1017:
1013:
1003:
998:
991:
987:
986:tuned circuit
983:
978:
964:
960:
957:
956:
953:
950:
947:
946:
942:
939:
936:
935:
932:
929:
926:
925:
922:full-carrier
921:
918:
915:
914:
911:
908:
905:
902:
901:
897:
894:
891:
890:
886:
883:
882:
879:
877:
874:In 1982, the
867:
864:
860:
856:
852:
841:
839:
828:
826:
822:
818:
814:
813:on–off keying
810:
800:
798:
794:
790:
789:amateur radio
786:
782:
778:
774:
770:
766:
760:
758:
754:
753:high fidelity
749:
748:digital radio
745:
741:
737:
733:
729:
724:
722:
718:
714:
710:
706:
705:
699:
697:
692:
690:
686:
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679:
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581:
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569:
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511:
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501:
497:
493:
490:
486:
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478:
474:
464:
462:
458:
454:
450:
446:
442:
441:amateur radio
438:
434:
429:
427:
423:
419:
415:
411:
407:
403:
398:
396:
392:
388:
384:
380:
376:
372:
368:
364:
360:
356:
345:
340:
338:
333:
331:
326:
325:
323:
322:
317:
314:
312:
309:
307:
304:
302:
299:
297:
294:
292:
289:
287:
284:
282:
279:
277:
274:
272:
269:
267:
264:
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259:
257:
254:
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248:
247:
246:
242:
241:
236:
233:
231:
228:
226:
223:
221:
218:
217:
216:
215:
212:
209:
208:
203:
200:
198:
195:
194:
193:
192:
189:
186:
185:
180:
177:
175:
172:
170:
167:
165:
162:
160:
157:
155:
152:
150:
147:
145:
142:
140:
137:
135:
132:
130:
127:
125:
122:
120:
117:
116:
115:
114:
111:
108:
107:
102:
99:
97:
94:
92:
89:
87:
84:
82:
79:
77:
74:
73:
72:
71:
68:
65:
64:
60:
56:
55:
52:
49:
46:
45:
39:
34:
30:
19:
4653:
4162:
4137:broadcasting
3770:Multiplexing
3645:Transmission
3610:Nikola Tesla
3600:Henry Sutton
3555:Samuel Morse
3485:Robert Hooke
3450:Amos Dolbear
3385:John Bardeen
3304:
3284:Telautograph
3188:Mobile phone
3143:Edholm's law
3126:social media
3059:Broadcasting
2962:
2941:
2935:Bibliography
2906:
2897:
2891:
2882:
2876:
2864:. Retrieved
2855:
2845:
2826:
2820:
2801:
2795:
2775:
2768:
2748:
2729:(1984) p.211
2726:
2721:
2713:
2709:
2704:
2692:. Retrieved
2680:
2668:
2600:
2549:
2517:
2511:and class-E
2501:transmitters
2498:
2490:
2475:
2466:
2433:
2415:
2336:
2290:
2183:
2169:
2149:
2129:
2118:
2115:
2095:
2091:
2087:
2076:
2065:
2058:
2054:
2050:
2046:
2042:
2038:
2030:
2028:
2007:
1999:
1997:
1759:
1755:
1749:
1744:
1740:
1736:
1728:
1726:
1518:(1 + m(t)/A)
1517:
1513:
1509:
1506:(1 + m(t)/A)
1505:
1501:
1497:
1493:
1491:
1352:
1345:
1341:
1337:
1335:
1259:
1252:
1246:
1217:
1205:
1191:
1143:
1140:Vacuum tubes
1121:transmitters
1101:Ernst Ruhmer
1094:
1065:heterodyning
1054:
1048:
1037:
1028:damped waves
1008:
990:(cone shape)
989:
887:Description
873:
858:
854:
847:
837:
834:
806:
803:Shift keying
761:
725:
702:
700:
693:
688:
684:
682:
669:
665:
605:
604:
512:
508:demodulation
503:
500:video signal
496:audio signal
470:
430:
417:
413:
399:
375:audio signal
358:
354:
353:
316:Multiplexing
256:Demodulation
75:
29:
4585:Cable radio
4528:Technical (
4288:DVB-T2 Lite
4144:Terrestrial
3970:NPL network
3682:Radio waves
3620:Alfred Vail
3530:Hedy Lamarr
3515:Dawon Kahng
3475:Elisha Gray
3435:Yogen Dalal
3360:Nasir Ahmed
3294:Teleprinter
3158:Heliographs
3003:, by C Foh.
2920:Harris Corp
2866:8 September
2712:, Volume 1—
2110:spectrogram
1146:Audion tube
1129:Poulsen arc
1044:interrupter
1002:vacuum tube
884:Designation
863:compression
838:transmitter
809:binary data
793:medium wave
473:electronics
261:Line coding
4467:DirectBand
4453:Subcarrier
4155:modulation
4016:Antarctica
3975:Toasternet
3897:Television
3380:Paul Baran
3312:Television
3296:(teletype)
3289:Telegraphy
3267:transistor
3245:Phryctoria
3215:Photophone
3193:Smartphone
3183:Mass media
2912:US 4580111
2759:0852962185
2725:AT&T,
2714:Principles
2708:AT&T,
2660:References
2550:clamp tube
2407:compressor
2399:distortion
1052:sinusoidal
1024:Morse code
821:Morse code
797:short wave
757:talk radio
485:modulation
467:Foundation
367:radio wave
363:modulation
51:modulation
4530:AM stereo
4389:Sirius XM
4382:providers
4301:Satellite
4000:Americas
3989:Locations
3960:Internet2
3721:Bandwidth
3425:Vint Cerf
3322:streaming
3300:Telephone
3240:Semaphore
3131:streaming
2623:AM stereo
2569:adjusted.
2463:coupling.
2422:broadcast
2176:onwards.
2004:sidebands
1969:ϕ
1966:−
1945:−
1927:π
1916:
1902:ϕ
1860:π
1849:
1803:π
1794:
1690:π
1679:
1660:ϕ
1641:π
1630:
1470:ϕ
1451:π
1440:
1420:ϕ
1401:π
1390:
1303:π
1294:
1249:sine wave
1218:In 1915,
1170:modulated
1069:detectors
958:Lincompex
943:emission
746:(FM) and
721:bandwidth
717:sidebands
639:ϕ
619:ω
576:ϕ
567:ω
561:
555:⋅
481:mechanics
389:, or its
383:frequency
371:amplitude
4687:Category
4629:Cultural
4559:Magnavox
4532:formats)
4482:SCA/SCMO
4477:RDS/RBDS
4280:HD Radio
4270:DRM/DRM+
4265:DAB/DAB+
4068:Category
3955:Internet
3945:CYCLADES
3862:Ethernet
3812:Concepts
3736:terminal
3687:wireless
3510:Bob Kahn
3353:Pioneers
3178:Internet
3069:Cable TV
2860:Archived
2858:: 22ff.
2685:Archived
2617:See also
2132:baseband
2043:1 + m(t)
2017:Spectrum
1504:< 1,
1235:Analysis
1229:longwave
1198:AT&T
1196:such as
1071:able to
704:envelope
393:, as in
361:) is a
243:See also
48:Passband
4455:signals
4423:AMR-WB+
4275:FMeXtra
4088:Commons
4078:Outline
4031:Oceania
3950:FidoNet
3935:ARPANET
3748:circuit
3317:digital
3046:History
2694:15 July
2649:Airband
2509:class-D
2403:limiter
2173:reduced
1202:carrier
1073:rectify
972:History
961:linked
759:etc.).
740:decibel
504:carries
4549:Harris
4544:C-QUAM
4433:HE-AAC
4410:Codecs
4394:Canada
4360:DVB-SH
4334:S band
4329:L band
4315:C band
4239:L band
4130:Analog
4026:Europe
3996:Africa
3980:Usenet
3940:BITNET
3877:Mobile
3753:packet
3262:MOSFET
3257:device
3054:Beacon
2948:
2925:
2914:,
2833:
2808:
2783:
2756:
2654:DSB-SC
2635:(AMSS)
2337:So if
2291:where
2244:
2235:
2217:
1750:Using
1492:where
1185:until
1111:, and
457:modems
169:SC-FDE
4539:Belar
4365:S-DMB
4355:DAB-S
4260:CAM-D
4173:COFDM
4152:Radio
4009:South
4004:North
3965:JANET
3902:Telex
3892:Radio
3731:Nodes
3726:Links
3647:media
3225:Radio
3210:Pager
3138:Drums
3104:video
3099:image
3089:audio
2688:(PDF)
2677:(PDF)
2603:diode
2534:choke
2411:vogad
2119:above
2075:and
2045:with
728:noise
426:power
418:DSBAM
391:phase
266:Modem
4487:DARC
4462:AMSS
4443:DRA+
4324:band
4233:high
4132:and
4021:Asia
3907:UUCP
3867:ISDN
2946:ISBN
2868:2017
2831:ISBN
2806:ISBN
2781:ISBN
2754:ISBN
2696:2018
2587:The
2312:and
2092:m(t)
2088:m(t)
2051:c(t)
2047:c(t)
2039:m(t)
2031:m(t)
2000:c(t)
1514:c(t)
1160:and
795:and
730:and
676:and
606:A(t)
479:and
404:and
306:OFDM
235:THSS
230:FHSS
225:DSSS
139:MFSK
124:APSK
4472:PAD
4428:HDC
4418:AAC
4370:SDR
4350:ADR
4284:CDR
4243:UHF
4229:mid
4225:low
4221:VHF
3912:WAN
3882:NGN
3872:LAN
3153:Fax
3094:DCT
2434:not
2377:1.0
2351:0.5
2081:– f
2070:+ f
2057:at
1913:sin
1846:sin
1791:sin
1676:sin
1627:cos
1437:cos
1387:cos
1291:sin
948:C3F
937:B8E
927:J3E
916:H3E
903:R3E
892:A3E
811:is
558:cos
471:In
461:QAM
408:'s
311:FDM
301:ΔΣM
296:PWM
291:PDM
286:PCM
281:PAM
276:PoM
271:AnM
220:CSS
202:WDM
197:QAM
179:WDM
174:TCM
164:QAM
159:PSK
154:PPM
149:OOK
144:MSK
134:FSK
129:CPM
119:ASK
101:SSB
91:QAM
4689::
4231:/
4227:/
4215:HF
4211:SW
4205:MF
4201:MW
4195:LF
4191:LW
4168:FM
4163:AM
2854:.
2734:^
2683:.
2679:.
2413:.
2037:,
2013:.
1754:,
1520::
1358::
1210:.
1107:,
1103:,
1099:,
855:no
698:.
680:.
510:.
483:,
475:,
463:.
451:,
447:,
443:,
439:,
435::
397:.
359:AM
96:SM
86:PM
81:FM
76:AM
4322:u
4320:K
4245:)
4241:(
4235:)
4223:(
4217:)
4213:(
4207:)
4203:(
4197:)
4193:(
4122:e
4115:t
4108:v
4039:)
4035:(
3030:e
3023:t
3016:v
2987:.
2971:.
2952:.
2870:.
2839:.
2814:.
2789:.
2762:.
2698:.
2374:=
2371:m
2348:=
2345:m
2320:A
2299:M
2274:A
2271:M
2266:=
2261:A
2257:)
2254:t
2251:(
2248:m
2241:f
2238:o
2232:e
2229:u
2226:l
2223:a
2220:v
2214:k
2211:a
2208:e
2205:p
2198:=
2195:m
2098:c
2096:f
2083:i
2079:c
2077:f
2072:i
2068:c
2066:f
2061:i
2059:f
2055:m
2010:c
2008:f
1982:.
1978:]
1973:)
1963:t
1959:]
1953:m
1949:f
1940:c
1936:f
1931:[
1924:2
1920:(
1910:+
1906:)
1899:+
1896:t
1892:]
1886:m
1882:f
1878:+
1873:c
1869:f
1864:[
1857:2
1853:(
1842:[
1838:m
1835:A
1830:2
1827:1
1822:+
1819:)
1816:t
1811:c
1807:f
1800:2
1797:(
1788:A
1785:=
1782:)
1779:t
1776:(
1773:y
1760:t
1758:(
1756:y
1745:t
1743:(
1741:y
1737:m
1729:m
1707:)
1703:t
1698:c
1694:f
1687:2
1683:(
1673:A
1669:]
1664:)
1657:+
1654:t
1649:m
1645:f
1638:2
1634:(
1624:m
1621:+
1618:1
1614:[
1610:=
1600:)
1597:t
1594:(
1591:c
1587:]
1581:A
1577:)
1574:t
1571:(
1568:m
1562:+
1559:1
1555:[
1551:=
1544:)
1541:t
1538:(
1535:y
1510:m
1502:m
1498:M
1494:m
1488:,
1474:)
1467:+
1464:t
1459:m
1455:f
1448:2
1444:(
1434:m
1431:A
1428:=
1424:)
1417:+
1414:t
1409:m
1405:f
1398:2
1394:(
1384:M
1381:=
1378:)
1375:t
1372:(
1369:m
1355:c
1353:f
1348:m
1346:f
1342:t
1340:(
1338:m
1332:.
1319:)
1316:t
1311:c
1307:f
1300:2
1297:(
1288:A
1285:=
1282:)
1279:t
1276:(
1273:c
1260:A
1255:c
1253:f
836:(
689:t
687:(
685:A
670:t
668:(
666:A
648:)
645:t
642:(
601:.
588:)
585:)
582:t
579:(
573:+
570:t
564:(
552:)
549:t
546:(
543:A
540:=
537:)
534:t
531:(
528:m
416:(
357:(
343:e
336:t
329:v
20:)
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