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IF we use frequency modulation for transmitting video signal this can cause phase shifting .and eyes can percieve this distortion effect easly . and requires more bandwidth to send the signal .Color levels are adjusted by amplitude in TV .So it s more logic to use Amplitude modulation .
Wiki User
∙ 12y ago
Wiki User
∙ 12y agobecause video transmission requires amplitude modulation......buahaha
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What is the difference between the AM modulation and ASK modulation?
This is hard to explain. AM means amplitude modulation, while ASK is amplitude-shift keying. AM is usually analog as it is modulated based on the strength of the signal, though you can use it to send a digital signal. ASK represents digital data as variations in the amplitude of a carrier wave. Any digital modulation technique will represent the data using a finite number of different signals. While AM is used mostly for radio and television, ASK is used for telegraph signals, transmission across telecommunications equipment, and fiber optics.
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.
What is square law diode modulator?
Methods of amplitude modulation can be put in the two categories namely Linear modulation methods and Square law modulation methods. Linear modulation method utilizes the linear region of the current voltage characteristics of the amplifying device that is transistor or electron tube. Square law modulation method utilizes the square law region of some current voltage characteristics of a diode or transistor or electron tube. A large number of linear modulation methods have been devised and have been used to varying degree. These methods are namely linear shunt plate modulation or anode choke modulation, linear series plate modulation, grid bias modulation, cathode modulation, suppressor grid modulation, screen grid modulation, collector modulation. Square law modulation circuits make use of non linear current voltage characteristics of diodes or triodes and are in general suited for use at low voltages. Important square law modulation methods are square law diode modulation and balanced modulator.
What are the advantages and disadvantages of phase modulation?
Advantage - 1. Phase modulation & demodulation is easy compared to Frequency modulation. 2. Phase modulator is used in determining velocity of moving target by extracting Doppler information. Doppler information needs stable carrier which is possible in phase modulation but not in frequency modulation. Disadvantage - 1. Phase ambiguity comes if we exceed its modulation index pi radian(180 degree). 2. we need frequency multiplier to increase phase modulation index. Visit my website http://harshit.org
What is difference between modulated wave and carrier wave?
Carrier Wave: A carrier wave is a high-frequency electromagnetic wave that is used as the "carrier" or the base signal in a modulation process. It is typically a pure sine wave with a constant frequency and amplitude. The carrier wave by itself does not carry any information; it serves as a vehicle to carry the information from one location to another. In AM and FM radio broadcasting, the carrier wave is the primary signal transmitted by the radio station. Modulated Wave: A modulated wave is the result of combining the carrier wave with an information signal, such as an audio signal or data. Modulation is the process of varying the characteristics of the carrier wave (either its amplitude or frequency) in accordance with the information signal. There are two common types of modulation: Amplitude Modulation (AM) and Frequency Modulation (FM). In AM, the amplitude of the carrier wave is varied in proportion to the amplitude of the information signal. This variation encodes the information onto the carrier wave. In FM, the frequency of the carrier wave is varied in proportion to the amplitude of the information signal. This variation encodes the information onto the carrier wave. The modulated wave contains the information that needs to be transmitted, and it can be demodulated at the receiving end to retrieve the original information.
What type of modulation is used to carry the picture portion of a television signal?
Amplitude Modulation (AM) is used for the picture portion of a television transmission while Frequency Modulation (FM) is used for the audio portion.
Which type of modulation is used in TV transmission?
In television system for video transmission AM is used and for audio transmission FM is used....
Why FM is used for sound transmission whereas am is used for picture transmission?
FM is used for both. Phase modulation can be used as well. FM radio is generally clearer than AM because the information in AM is stored in the amplitude of the wave. As waves propogate, they collect noise, which distorts their amplitude. This generally does not happen to the frequency. FM, or frequency modulation stores the information in the frequency. Both are subjected to the same amplitude modulating noise, but since the information is encoded in a different way, it is not degraded.
How phase lock loop is used as a universal detector for Amplitude Modulation?
I could certainly be wrong, but my recollection is that a phase locked loopis a universal detector for Frequency and Phase modulation, and is quiteinsensitive to Amplitude modulation.
How is pulse amplitude modulation transmitted?
Generally pulse amplitude modulation (PAM) is trasmitted as a series of DC levels and are mostly used in wired trasmissions (DC is not effective wirelessly).
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
How does amplitude modulation transmit ones to zeros?
Amplitude modulations can be used to transmit binary data. Remember AM modulation is done using a single carrier frequency, and increasing or decreasing the amplitude. A high amplitude would be considered a '1', and a low amplitude would be considered a '0' (typically).
What are the two types of wave communication used in broadcasting?
AM and FM AM=Amplitude Modulation FM=Frequency Modulation Hope this helps
What is analog modulation?
Analog modulationIn analog modulation, the modulation is applied continuously in response to the analog information signal.Common analog modulation techniques are:Amplitude modulation (AM) (here the amplitude of the modulated signal is varied) Double-sideband modulation (DSB) Double-sideband modulation with unsuppressed carrier (DSB-WC) (used on the AM radio broadcasting band)Double-sideband suppressed-carrier transmission (DSB-SC)Double-sideband reduced carrier transmission (DSB-RC)Single-sideband modulation (SSB, or SSB-AM), SSB with carrier (SSB-WC)SSB suppressed carrier modulation (SSB-SC)Vestigial sideband modulation (VSB, or VSB-AM)Quadrature amplitude modulation (QAM)Angle modulation Frequency modulation (FM) (here the frequency of the modulated signal is varied)Phase modulation (PM) (here the phase shift of the modulated signal is varied)
What is the difference between the AM modulation and ASK modulation?
This is hard to explain. AM means amplitude modulation, while ASK is amplitude-shift keying. AM is usually analog as it is modulated based on the strength of the signal, though you can use it to send a digital signal. ASK represents digital data as variations in the amplitude of a carrier wave. Any digital modulation technique will represent the data using a finite number of different signals. While AM is used mostly for radio and television, ASK is used for telegraph signals, transmission across telecommunications equipment, and fiber optics.
Why only AM but not FM used for transmitting video signal?
Because of video's complex nature, AM lends itself to transmitting several different signals simultaneously, like video, chroma, sync, etc. and it can provide the bandwidth required to do it easily. FM for the audio has a bandwidth of 100 khz, and FM is much better for that. It's also a `cleaner signal`, but the FM transmitter has limitations on how much information it can carry.
How do waves carry signals?
Waves can be varied (modulated) by either changing amplitude (amplitude modulation AM) or changing frequency (wavelength) (frequency modulation FM). The modulations are used to carry the information signal.
