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A modulation frequency of 40 cps with an amplitude as small as possible, commensurate with reasonably good signal-to-noise quality, was used.
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Some Related Sentences
modulation and frequency
In this, some base signal ( e. g., a sinusoidal carrier wave ) has one of its properties modulated: amplitude modulation involves altering the amplitude of a sinusoidal voltage waveform by the source information, frequency modulation changes the frequency.
Contrast this with frequency modulation, in which the frequency is varied, and phase modulation, in which the phase is varied.
In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands.
Broadcasters using analog television systems encode their signal using NTSC, PAL or SECAM analog encoding and then use RF modulation to modulate this signal onto a Very high frequency ( VHF ) or Ultra high frequency ( UHF ) carrier.
Further differences exist in the frequency and modulation of the audio carrier.
A channel actually consists of two signals: the picture information is transmitted using amplitude modulation on one frequency, and the sound is transmitted with frequency modulation at a frequency at a fixed offset ( typically 4. 5 to 6 MHz ) from the picture signal.
This noise can be avoided by modulation of the signal at a higher frequency, for example through the use of a lock-in amplifier.
Another feature to make LS AAS element-specific is modulation of the primary radiation and the use of a selective amplifier that is tuned to the same modulation frequency, as already postulated by Alan Walsh.
* the maximum modulation frequency ( or range of modulation frequencies ) of an optical modulator
modulation and 40
The UK channels that were legalised on 2 November 1981 were on two blocks of frequencies: 40 channels on the 27 MHz band and 20 channels on the 934 MHz band, both of which used FM ( frequency modulation ) and both unique to the UK.
" Over the course of those 39 years, many top 40 stations had graced the amplitude modulation band in Southern California.
modulation and with
Another important break with the past was the radical overhaul of opera by Christoph Willibald Gluck, who cut away a great deal of the layering and improvisational ornament and focused on the points of modulation and transition.
It is possible that each of these ion species has a family of channel types each with its own biophysical characteristics relevant to synaptic input modulation.
In 1975, the Japanese company Yamaha licensed the algorithms for frequency modulation synthesis ( FM synthesis ) from John Chowning, who had experimented with it at Stanford University since 1971.
This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant.
In radio systems, frequency modulation with sufficient bandwidth provides an advantage in cancelling naturally-occurring noise.
The harmonic distribution of a sine wave carrier modulated by such a sinusoidal signal can be represented with Bessel functions ; this provides the basis for a mathematical understanding of frequency modulation in the frequency domain.
The group velocity of a wave is the velocity with which the overall shape of the waves ' amplitudes — known as the modulation or envelope of the wave — propagates through space.
In June 2004, in a signed agreement with the United States, the European Union agreed to switch to a modulation known as BOC ( 1, 1 ) ( Binary Offset Carrier 1. 1 ) allowing the coexistence of both GPS and Galileo, and the future combined use of both systems.
The Japanese-made Uni-Vibe, designed to simulate the modulation effects of the rotating Leslie speaker, provided a rich phasing sound with a speed control pedal, and is heard on the Band of Gypsys track " Machine Gun ", which highlights use of the Uni-Vibe, Octavia and Fuzz Face.
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted.
In music synthesizers, modulation may be used to synthesise waveforms with an extensive overtone spectrum using a small number of oscillators.
*** Double-sideband modulation with carrier ( DSB-WC ) ( used on the AM radio broadcasting band )
Carry out the modulation, for example by multiplying the sine and cosine waveform with the I and Q signals, resulting in the equivalent low pass signal being frequency shifted to the modulated passband signal or RF signal.
Non-coherent modulation methods do not require a receiver reference clock signal that is phase synchronized with the sender carrier wave.
However, they only work with relatively constant-amplitude-modulation signals such as angle modulation ( FSK or PSK ) and CDMA, but not with QAM and OFDM.
Nevertheless, even though switching amplifiers are completely unsuitable for normal QAM constellations, often the QAM modulation principle are used to drive switching amplifiers with these FM and other waveforms, and sometimes QAM demodulators are used to receive the signals put out by these switching amplifiers.
Some pulse modulation schemes also allow the narrowband analog signal to be transferred as a digital signal ( i. e. as a quantized discrete-time signal ) with a fixed bit rate, which can be transferred over an underlying digital transmission system, for example some line code.
modulation and amplitude
* AM broadcasting, radio broadcasting using amplitude modulation
In the mid-1870s, a form of amplitude modulation — initially called " undulatory currents "— was the first method to successfully produce quality audio over telephone lines.
Amplitude modulation resulting in two sidebands and a carrier is called " double-sideband amplitude modulation " ( DSB-AM ).
In 1982, the International Telecommunication Union ( ITU ) designated the types of amplitude modulation:
Ring modulation, also known as amplitude modulation, is an effect made famous by Doctor Who's Daleks and commonly used throughout sci-fi.
Note that the RF signal modulation is inverted compared to the conventional AM: the minimum video signal level corresponds to maximum carrier amplitude, and vice versa.
Popular analog modulation techniques include amplitude modulation and frequency modulation.
For particular values of the modulation index, the carrier amplitude becomes zero and all the signal power is in the sidebands.
* Amplitude modulation ( AM ) ( here the amplitude of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal )
** Quadrature amplitude modulation ( QAM )
modulation and small
* For small amplitude signals, PM is similar to amplitude modulation ( AM ) and exhibits its unfortunate doubling of baseband bandwidth and poor efficiency.
The undesired signals are removed by the IF bandpass filter, leaving only the desired offset IF signal at f < small >< sub > IF </ sub ></ small > which contains the original modulation ( transmitted information ) as the received radio signal had at f < small >< sub > d </ sub ></ small >.
The two sources of noise in delta modulation are " slope overload ", when steps are too small to track the original waveform, and " granularity ", when steps are too large.
Because the MO activity is usually very small, normally less than 1 °, in conventional systems, the monochromator produces quasi-monochromatic light in a narrow wavelength window since the amplitude of modulation is wavelength dependent.
In Broadcast band frequency modulation ( FM ), subcarriers above 75 kHz are limited to a small percentage of modulation and are prohibited above 99 kHz altogether to protect the ± 75 kHz normal deviation and ± 100 kHz channel boundaries.
If there is a ΔA, then a small AC voltage will be present that corresponds to the modulation frequency, ω.
Amplitude modulation has also been used in the non-contact regime to image with atomic resolution by using very stiff cantilevers and small amplitudes in an ultra-high vacuum environment.
Modified frequency modulation ( MFM ) controllers were the most common type in small computers, used for both floppy disk and hard disk drives.
The level of modulation applied for transmission is small enough that the power output essentially remains constant.
Due to the small size of the resonator, digital modulation can be very fast ( up to 500 MHz ).
PAL uses the same color modulation scheme as NTSC but averages the received color information over adjacent scan lines, resulting in reduced color detail but canceling out small to moderate phase errors.
A shoulder strap can be connected to it, and a small handgrip can be plugged into the side which contains a pitch bend wheel and a pitch modulation trigger.
When a shoulder strap is connected to it, and the small handgrip with a pitch bend wheel and a pitch modulation trigger is used, the SH-101 becomes a keytar.
The Yamaha SHS-10 from the late 1980s has a small keyboard with 32 minikeys and a pitch-bend wheel, an internal Frequency modulation ( usually referred to as FM ) synthesizer offering 25 different voices with 6-note polyphony.
The effect is fairly small in any case resulting in a ± 7 % modulation of the energetic neutron flux in New York City.
The modulation pattern over half a rotation for a single RMC provides the amplitude and phase of many spatial Fourier components over a full range of angular orientations but for a small range of spatial source dimensions.
These radio sets were designed to receive amplitude modulation ( AM ) broadcasts in the medium wave band, and were manufactured in the United States from the mid 1930s until the early 1960s ( FM broadcasting in the United States, while running on a small scale from 1930, only became widely popular in the late 1950s, with the trend towards high-fidelity audio ).
A small, high frequency sinusoidal modulation voltage is superimposed on the D. C. tip-sample bias.
By 1950 the small team at Ferranti Canada had built a working pulse-code modulation ( PCM ) radio system that was able to transmit digitized radar data over long distances.
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