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In order to send more than one bit at a time during a single phase on a carrier which modulation is used?
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In order to send more than one bit at a time during a single phase on a carrier modulation is used?
amplitude modulation is used
Why is modulation necessary in radiobroadcasting?
Modulation in radio broadcasting is important because it is necessary to adjust the carrier signal so that the information in the modulating signal can be broadcasted. You must have modulation in order to transmit thru a radio wave.
What are the advantages and disadvantages of double sideband suppressed carrier modulation?
Amplitude modulation of a carrier results in a transmitted signal consisting of the carrier, plus an 'upper sideband' and a 'lower sideband', spaced above and below the carrier frequency by the frequency of the modulation.The bandwidth of the whole signal is double the modulation frequency. Also, the power in the carrier is constant, and power must be added in order to radiate the sidebands.All the receiver needs in order to extract the information from the signal is one complete sideband, and knowledge of the frequency and phase of the carrier. Economically speaking, the carrier is wasted power, and the other sideband is wasted power andwasted spectrum.If you can filter away one of the sidebands before transmission, then you save half of the occupied spectrum, and the receiver has everything it needs to decode the signal. If you can also filter away the carrier ... or at least knock it way down ... before transmission, you can save a lot of power and use it for the remaining sideband, which extends your range for a given amount of power. The receiver still has everything it needs, as long as it can pick up a sniff of carrier ... enough to derive the carrier frequency and phase.This mode is known as "Single Sideband Suppressed Carrier". It's exactly how the video portion of standard NTSC analog TV was transmitted, throughout all of human history until June 2009.
What is positive and negative modulation?
in order to transmit the video signal amplitude modulation is used. the composite video signal has distinct polarity of black and white levels in the picture.1.positive modulation :- in this type of modulation, increase of brightness toward white causes increase in carrier amplitude peak white has 100% modulation while black and sync level have lower and minimum modulation respectively2.negative modulation :-in this type of modulation,the sync tip level are at 100%.blanking level correspond to black is at 75%and increase in brightness toward white causes decrease in carrier amplitudeNegative modulation is preferred over positive modulation because impulse interference is difficult to deal with and random increase in signal is similar to existing sync pulse.these interference result in generation of black spot and white blobs.
When you do modulation in time domain you get modulated waveform of modulating signal information and carrier. How can you recognize the upper and lower side bands in time domain modulated waveform?
You need modulation signal(carrier) which is a required signal in order to make envelope of time domained signal(target signal). The modulating signal is imposed on modulation signal.This creates envelope of waveform which is modulated(desired) signal. Now, the desired signals uper and lower sideband of signal strictly depends on modulation signal's bandwidth. Max. peak of that signal is uper sideband and min. peak is lower sideband for this modulated signal.
Which modulation can reduce the noice of signal?
Signals of different frequencies cannot interfere with each other. For example can audio waves (speech) interfere with AM or FM signals?? So when we perform modulation we just transfer the message to another amplitude/frequency/phase. Hence they will never interfere with signals which are not in the same range as them. Regards Arvind
What is the typical drawback of AM scheme over DSB-SC modulation scheme?
The trick is the SC...Suppressed Carrier. In this scheme, only the sidebands are emitted, and in order to demodulate, the carrier must first be re-inserted. This has to be done accurately, or the resultant audio will be garbled...it's called "Monkey Talk."
What is need of space vector pulse width modulation?
due to space vector modulation we can eliminate the lower order harmonics
Why you need modulation?
It might be helpful to have a working definition of modulation before making a statement as to why it is needed. In fact, with an understanding of what modulation is, it will be obvious why it is included in electronic communications.Modulation is the "message" or the "intelligence" that is impressed on a radio frequency (RF) carrier. When we transmit a signal, we generate a carrier frequency, and then we modulate it. We "add" the message or the information we wish to transmit by modulating the carrier in some way. There are at least a dozen different modulation schemes ranging from simple to real head scratchers. They either modify the amplitude, the frequency or the phase of the carrier. Let's look at a few.The simplest modulation technique is taking the transmitted signal and turning it on and off. It is "keyed" to send a series of pulses. Morse code uses on-off keying. In this method of modulation, no modification of the RF carrier signal itself is made. It is simply switched on and off. (It could be looked at as amplitude modulation with the carrier either at zero amplitude or at "maximum" amplitude with nothing in between.) A series of pulses can be transmitted. With Morse code, a short "on" period will send a dot or "dit" out. If we extend the "on" period a bit, we can send a dash or "dah" out. Nothing real sophisticated here, but basic and effective communication. There are obvious limits to how fast information can be transmitted with this modulation scheme. (But don't tell the hams who still use it!)Most of us are familiar with AM radio. AM is amplitude modulation. The amplitude of the RF carrier is modified to modulate it. The amplitude of the modulating signal will determine the amount that the amplitude of the carrier is changed. (The volume of the modulation determines how much the amplitude of the carrier is changed. The frequency of the modulating signal determines the rate of change of the amplitude of the carrier. (The frequency of the modulation determines how fast the amplitude of the carrier is changed.). The frequency of the carrier is held constant through all this.How about FM? In frequency modulation, the amplitude of the carrier is constant. It's left alone. But the frequency of the RF carrier is changed. It is swung above and below where it sits (it's assigned center frequency) at a rate proportional to the frequency of the modulating signal, and at an amount proportional to the amplitude of the modulating signal. In FM single sideband, the carrier frequency and the frequencies above the carrier are transmitted and the frequencies below the carrier are suppressed (upper sideband transmission). Or the frequencies below the carrier are transmitted with the carrier and the upper frequencies are suppressed (lower sideband transmission). In conventional television, the video signal is single sideband, suppressed carrier. It's like "regular" upper sideband transmission except the carrier signal is suppressed. Sideband transmission "saves" space on the RF spectrum. And it works because we really don't need "all" of the FM signal to demodulate the signal at the receiver.Other forms of modulation become more complex. CDMA (code division multiple access), TDMA (time division multiple access) and other methods are used in cell phones to modulate the carrier so the digital data stream can be impressed on the carrier.Modulation is the addition of intelligence to a carrier signal. It's the message. Modulation is necessary because the point of communication is getting the message through.A Simple answer:Simply this... Any communications medium: e.g. Free space - radio waves, Air - Sound waves or radio waves, Optical Fibre - Light, Copper Wires Electrical Anergy (with frequency limits of the copper wire construction) is made for a certain type of signal. But if the signal we want to send is not compatible with the medium, then it does not travel well.Modulation changes the information we want to send from it's original form, into one that is more compatable with the medium we are trying to use.For example, your computer speaks digital over a TCP/IP LAN which requires CAT 5 or better rated cables,, but to connect to your internet service provider (ISP), you need to send the signal over the wires of the telephone company (made for voice tones). To make this connection, and ADSL modem (modulator/demodulator) is used to convert the data into audio tones, which pass over the telephone line, and at the far end are converted back to digital to join the service providers network. in the reverse direct the ISP does the same, and the signals are de-modulated, back to data for your network.Or in simple terms, Its about best use of the medium. Everything else is just a away of doing it. And there are a lot of possible ways to choose.
If carrier is suppressed then what is the use of carrier in modulation?
If the carrier is suppressed, then the carrier is only needed at the modulation stage, in order to generate the sideband(s), and it needs to be regenerated at the demodulation stage, in order the recover the original signal. The purpose of suppressing the carrier is to increase the power to the signal-carrying portion of the transmission, by eliminating the "wasted" power in the carrier. This is done at the expense of complexity in the transmitter and receiver. More insight: Actually the added complexity is mainly at the receiver side. The two common methods for the carrier recovery of its receivers are: 1) squaring the DSB-SC signal then dividing by two. 2) the "Costas Loop". The third method, not known by IEEE yet, is "Kerim Loop" that uses a conventional PLL (VCO, phase comparator and an RC filter). It is therefore very simple to be implemented since it doesn't require selective filters of any kind. And it can be integrated to produce low cost AM receivers that recover the baseband signal for any AM modulation index, up to infinity which is the case of no carrier (DSB-SC). These new AM receivers would therefore have also both the features of the synchronous demodulator and the Automatic Frequency Control (AFC) function. Note: Since 30 years, to let "Kerim Loop" concept be known globally, I had to pay a good amount of money first! So, when necessary, I took advantage of it in my private links only.
What is the carrier of hereditary information called?
The transmission of hereditary information is associated with chromosomes. In order for a substance to act as a carrier of hereditary information it must be precisely copied during the cell cycle.
What is necessary in order to interpret a signal?
Operating system
