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yes
for transmission of the signal to take place smoothly,digital tranmission needs to be modulated over a carrier
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What is disadvantage in amplitude modulation with carrier?
The differeces between frequency and amplitude modulation does not effect the range. Fundamentally the amplitude modulation system is less efficient in that a carrier is generated, which is modulated. The modulation power is half of the carrier power. The bandwidth required is twice the highest modulating fequency. Because of the small bandwidth required, the Amplitude Modulated band on radios is from 550 Khz to 1500 Khz. Channels are separated by 10 Khz, with actual users usually separated by 2 or three channels minimum. Frequency modulation varys the frequency of the carrier by the audio modulating component. While the frequency deviation can be as low as the audio frequency modulating the carrier, better noise performance is achieved by deviating the carrier by as much as possible. In commercial broadcast operations, the 15 Khz audio signal deviated the carrier by 75 Khz. This presents exceptionally good audio reproduction. It also causes the FM (Frequency Modulated) signal to occupy a band of about 240 Khz for a 15 Khz audio channel. This compares to 30 Khz for an equivalent AM (Amplitude modulated) signal. Because of the larger bandwidth required, the FM broadcast band is moved higher in frequency. This makes the other comments about range etc come into effect. AM signals can be received even when an interfering signal is present. Weak signals can be received in the presence of strong signals. Because of this property, Aviation signals, (Airplane to control tower and tower to plane) are in AM. FM signals have an effect called "capture effect" in which a stronger signal will capture the channel and eliminate interference from the weaker signal. Basically you are trading bandwidth for interference rejection. Because of this, signals from satellites, where the signal strength is extremenly small, used to be sent in FM. Present technology uses digital broadcast techniques. Talking about digital, because of the ability of digital receivers to process signals of extremely small size, digital signals are being sent along with both AM and FM broadcast signals for either better quality, or supplementary services. Cell phones are all being switched over to digital technology for better reliability and better channel usage.
Why are over modulated and carrier suppressed AM signals a problem from the standpoint of the receiver?
-- An over-modulated AM signal spreads to occupy excessive RF bandwidth. If it'snot the one you happen to be listening to but it's close, then its outlying productscan lop over into the adjacent channel where they don't belong, and show up asdestructive interference to the one you're trying to hear. If it is the one you'relistening to, then its outlying sidebands typically exceed the bandwidth of yourreceiver, and the recovered audio to which you're listening includes excessiveaudio distortion.-- A carrier suppressed AM signal is only a problem if the receiver's beat-oscillatorlacks sufficient stability. The receiver is responsible for providing the carrier locally,which needs to be very close to phase-locked to the missing carrier for decentaudio, and produces weird-sounding audio indeed if it's far from correct phase, orwandering.The best approach to receiving carrier-suppressed AM is to begin by sharp-filteringthe received signal so as to retain only one sideband, since the frequency- andphase-stability requirements on the local oscillator are actually less stringent forsingle-sideband detection. But there you go again with a more complex receiver.
What is carrier telephony and what are the features of carrier telephone system?
Carriers are the companies that construct and maintain the networks that provide telephone services. Carrier telephony is a method of transmitting several telephone channels over a single pair of wires. It was used extensively throughout the world in the 1940s through 1980s prior to the introduction of digital transmission systems. Carrier telephony systems ranged from single channel systems that transmitted one carrier channel on top of a normal voice frequency channel to co-axial cable systems that had thousands of channels. It was mostly used to provide trunk lines between cities although subscriber carrier systems did exist.
What is the main advantage of digital transmission over analog transmission?
digital signal is less susceptible to signal degradation due to the nature of it's transmission signal which is either on or off and therefore less errors occur as analog is prone to signal degradation and loss that is why digital tv is crisp and clear and analog is somewhat blurry in comparison, also with higher bandwidth achievable by digital transmission more data is able to be transmitted.
Who invented the air conditioning?
Willis Carrier over a period of time from 1902 though 1911. He is the founder of the Carrier Corporation and Carrier brand air conditioners. There are several sub-brands, Bryant, Day-and-Night.
What is digital data transmission?
Digital data transmission use voltage differences to directly represent the 1s and 0s that make up the data and are not modulated over a carrier.
What is fading in telecommunications?
In wireless communications, fading is deviation or the attenuation that a carrier-modulated telecommunication signal experiences over certain propagation media.
What if the signal is over modulated?
If a signal is over modulated, there will be rests or breaks in the steam. The connection on the other end will be blurry, short-circuited, or not follow through itself. clara-the-awesomest.tumblr.com
What do modem stand for?
MODEM stands for MOulator/DEModulator. It is a device that translates a data bit stream from a digital device into a modulation signal and modulates a carrier for transmission over wires. Since it can also receive data streams it must be able to demodulate the carrier and translate the modulated intelligence back into a data bit stream.
Will a carrier that undergoes over modulation occupy a greater or a lesser bandwidth than a carrier which is 80 percent modulated?
Overmodulation always produces a greater occupied bandwidth, unless you do some serious filtering before it gets out.
What is the digital pulse modulation?
There are 3 main types of digital pulse modulation:Pulse time modulation (PTM), somewhat similar to analog phase modulation.Pulse width modulation (PWM), the width of the pulse represents the signal.Pulse code modulation (PCM), serial transmission of binary bits forming numeric or character codes that represent the signal.All of these can be modulated on an RF carrier using any of the standard modulation techniques: AM, FM, Phase Modulation, etc. One advantage with AM digital pulse modulation techniques over AM analog is that the carrier can be 100% modulated, which cannot be done with analog, thereby allowing significant reductions in transmitter power without loss of coverage range. Sometimes FM digital pulse modulation techniques are referred to as Frequency Shift Keying (FSK). A very complex method of combining Phase Modulation and AM to increase the bit density of digital pulse modulation on an RF carrier is called Quadrature Amplitude Modulation (QAM).
What is the Digital modulation?
There are 3 main types of digital pulse modulation:Pulse time modulation (PTM), somewhat similar to analog phase modulation.Pulse width modulation (PWM), the width of the pulse represents the signal.Pulse code modulation (PCM), serial transmission of binary bits forming numeric or character codes that represent the signal.All of these can be modulated on an RF carrier using any of the standard modulation techniques: AM, FM, Phase Modulation, etc. One advantage with AM digital pulse modulation techniques over AM analog is that the carrier can be 100% modulated, which cannot be done with analog, thereby allowing significant reductions in transmitter power without loss of coverage range. Sometimes FM digital pulse modulation techniques are referred to as Frequency Shift Keying (FSK). A very complex method of combining Phase Modulation and AM to increase the bit density of digital pulse modulation on an RF carrier is called Quadrature Amplitude Modulation (QAM).
What is meaning of MODEM?
According to Encyclopedia Britannica, Modem is an electronic device that converts digital data into analog (modulated-wave) signals suitable for transmission over analog telecommunications circuits (e.g., traditional phone lines) and demodulates received analog signals to recover the digital data transmitted. The "modulator/demodulator" thus makes it possible for existing communications channels to support a variety of digital communications, including e-mail, Internet access, and fax transmissions. An ordinary modem, operating over traditional phone lines, has a data transmission speed limit of about 56 kilobits per second. ISDN lines allow communications at over twice that rate, and cable modems and DSL lines have transmission rates of over a million bits per second.________________________________________________________________A modem ( from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information.
What are the advantages of digital modulation over analog modulation?
1)digital modulation can easily detect and correct the noise. where as analog modulation has little complexity 2)security is more in digital modulation 3)digital modulated signal can traverse a long distance compared to analog modulation
What are the Advantage of digital modulation over analog modulation?
1)digital modulation can easily detect and correct the noise. where as analog modulation has little complexity 2)security is more in digital modulation 3)digital modulated signal can traverse a long distance compared to analog modulation
What is over-modulating condition in term of amplitude modulation?
When your audio modulating signal is larger than your RF carrier amplitude the peak of the modulated carrier will become flat and a distorted audio signal with flattened peaks will be send out from the detector on the receiver side
If modulation index is greater than one than what happens?
it causes over modulation .... that is the phase reversal of carrier signal ..... the modulated wave then exhibits envelope distortion which results in loss of data .....
